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Burners, Atmospheric, Considerations, Addendum on Wood

Kiln Burner Painting

Venturi Burner by Louis Katz , all-weather paint stick on plywood, torched.

Nothing in this post should be considered safety information. A lot of it is just what I think, not having read it anywhere in a format I could really understand. Other information I am consolidating.

Atmospheric burners are not understood particularly well by ceramic artists. I am going to try and clarify some things about them. I have not found any wonderful texts about them, most of what I know has been gleaned from catalogs that used to provide much more information than can be found now. While this is almost exclusively Eclipse® and Pyronics® catalogs others have entered into the mix.  To simplify things I am only going to consider Natural gas, an impure methane that is generally delivered through pipes to homes and businesses. I live in the US. So its possible that something I say will only be applicable here,,, but I can’t think what that would be.

Entrained Air
An atmospheric burner with a venturi tube is a device whose function is to efficiently use the kinetic energy of gas coming out of an orifice to carry air with it. The air that it carries through the burner is called “entrained air” also “primary air”. 

Orifice
The orifice that the gas flows out of is called the orifice, sort of a truism. The size of the orifice and the pressure the gas is under determines how many BTUs, calories, or cubic feet of gas are flowing into the burner. Orifices that are properly made and drilled create less turbulence when the gas exits the orifice and prevents loss of kinetic energy. This consequently increases the amount of air that will or can be entrained. We will discuss this further below in several places.

Primary Air
Primary air is the air entrained in the burner. The air coming into the kiln around the end of the burner is secondary air.  I guess much of this is redundant. It seemed needed. 

Flame Retention Ring
These are devices on the kiln end of the venturi tube whose job is to efficiently mix the gas and air, create a faster area for the mixed gas and air to flow through, and often provide a small amount of slower gas around the circumference to act as a pilot for the flame so that it will always light near the Retention Ring.  The faster speed is so that the mixed gas and air is moving out quicker than it is burning back into the burner. If the speed in the retention ring is too slow then you get back burning, burning inside the venturi tube. This creates soot and other troubles.

Methane – CH4

How Atmospheric burners, a mixer head where the orifice and air come, a venturi or straight tube, and flame retention ring, are sized.

The exact amount of oxygen (from air) needed to burn a molecule of methane, CH4, into carbon dioxide and water is CH4 +2O2 = CO2 + 2H20,, two molecules of O2. How much is this by volume or weight is not really important. But this ratio, we will call Neutral Combustion.

If it were only the gas we were concerned with then burners would be sized by the size of the gas orifice. You would not use a burner, and just pump gas into the kiln. All the air would be brought in with the chimney and the kiln would need to be kept at a higher negative pressure to do this. But there are two problems with this. One is that any leaks in the kiln will bring larger amounts of air in, and if they are not near the gas source then they will cool those areas, and keep them oxidizing more than anyone would need them to be. The second problem is that you need mixing of gas and air.  Gas heated in the absence of enough oxygen will produce soot, pure or nearly pure carbon. [This is hard on people contributing to heart disease, lung disease and cancer along with particulate pollution and other environmental effects.] Soot can be very slow to burn. There may be times when you want soot such as carbon trapping glazes but for the most part it is usually just wasted fuel. Assuming that the mixing of gas and air before heating is good, then this happens when the oxygen is less than 1/2 of the amount needed. CH4+O2 = C +2 H2O. In general this is a good way to waste fuel. In small gas kilns some of this burns in the chimney, but some does not. Unfortunately Carbon does not reduce carbon dioxide to monoxide, at least not easily as far as I know. I suspect that if you heat carbon and carbon dioxide hot enough you will get carbon monoxide forming,,, but I do not know enough to be sure of this. Perhaps a chemist will chime in.

[I recently found a copy of a a catalog for the  now unavailable single state Low Pressure Injectors from Eclipse. It gives numbers for 30-50% entrainment. This does not fit my memory or understanding.  Eclipse Atmospheric Injectors, Bulletin 650, 1/8/2015]

The charts that I have seen for burners being sold generally state an assumed amount of entrained air. For example; These numbers may assume that some percentage of the air needed for neutral combustion will be entrained by the burner. That is, a little over 1/2 the air needed to completely burn the gas will be entrained by the burner (or mixed in at the burner tip as secondary air). You will get some CO2 from this air, but most of the carbon will leave as CO which will still burn if more air, more O2, is provided. You only need or want a little CO for reduction. Too much and your kiln will not climb in temp and you will waste time, fuel, money. Too little will be talked about under mixing a few paragraphs down. 

The rest of the air needed is supplied by secondary air coming in around the flame retention ring. The O2 in this air burns the CO into CO2.

Why do you get more BTUs with higher pressures?


Lets just say you have a cubic meter, or cubic yard if you insist, of gas. I find it easier to image this with more gas especially when it is at a very low pressure, say 1cm water column, or 1 inch water column if you prefer. The gas, coming out of the orifice will come out slowly and will have little kinetic energy in the stream. In fact it will only have the kinetic energy used to compress it. If you use way more energy to compress the gas you will also need a smaller orifice if the gas is going to come out at the same rate. But having put more energy in you get more energy out. This energy, in part transfers to the air coming into the burner, in fact this energy is what draws air into the burner. I find it easier to visualize with the idea that the gas coming out the orifice blows air out of the burner, the air then needs to be replaced so more is drawn in. High pressure, small orifice, entrains more air because there is more “blow”, more kinetic energy, in the gas. More air means that keeping to 65% of what you need for full combustion, means you can use more gas. More gas means even more kinetic energy. Higher pressures increase the capacity of the burner. However they also increase turbulence. At some point the amount entrained in the burner no longer increases much as the pressure increases. When you get to the point where the air that can be entrained drops below 65% of that needed you have reached the maximum practical pressure of the burner.  Eclipse and Pyronics used to release good charts on their burners that mostly made this clear if you studied the numbers. 

Negative pressure at the burner port.

If  kiln is hot and the damper open you can get a slight decrease in pressure at the burner port. Assuming that the burner is placed properly in relation to the port, this decrease in pressure will allow more air to be pushed (or pulled if you like) through the burner,,, . I think of this lower pressure as sucking air through the burner. [The sucking or pulling is an easier model but is not technically correct.]  Lets assume that you make those ports too big. In order to get a given volume through them you need only a little pressure difference. As they get smaller, the pressure in the ports is going to fall. This increases the capacity of the burners because it decreases the pressure at the burner head. There needs to be enough space around them for the requisite secondary air. [100%-65%=35%]. But often these ports are made too large if the goal is maximizing the capacity of the burners so that you can heat faster.

Further the flame retention ring acts in respect to the burner port similar to the gas in the burner and carries secondary air into the kiln using its kinetic energy.

Mixing

In order for the gas to burn it has to be in contact with the oxygen in the air. If it gets hot without the air it won’t burn. If it gets hot with only a little air you will get soot. The most important mixing happens before it burns, in the flame retention ring. Burners made without them have the potential to waste a lot of fuel as soot . CH4+O2 = C +2 H2O. Interestingly higher gas pressure should produce more turbulence in a given amount of time but the gases also move through the burner body quicker. I think that you end up with better mixing, but I am not sure.  It does appear that you get better mixing with the secondary air.

About 68 percent of the heat in methane is released burning it to carbon monoxide. Knowing this makes it clear why firing closer to neutral is quicker. I like to think if firing with too little air, firing in too much reduction, as being like paddling upstream with a small paddle.

Bad mixing, too little primary air, soot, once the kiln is quite hot,  can make determining if you are reducing difficult. The soot can be burning off in the flue making flame and looking like reduction. The same can happen out spyholes. You can close down one burner’s primary air and get soot, have the kiln oxidize and have flame at the spy holes (bungs) and at the flue.

While we are on it, the flame does not come out of the kiln unless there is oxygen that is not yet combined coming out as well. The flames we normally see from uncombusted gases coming out from the kiln are hollow and start where they come in contact with fresh air. Paying attention to this, especially in wood or oil kilns can save a lot of heartache and trouble.

Heat is released when all the necessities for combustion are met, heat, O2, fuel and mixing. Well I suppose they are not in the same place unless they are mixed, but that is a fine point. The sooner good mixing takes place the sooner the heat is released. Since primary air mixes at the burner, secondary air released later in the kiln chamber. Up to a point this can be used to control temp in different parts of the kiln. 

Mixing is always imperfect. As you approach neutral combustion you should assume that some parts of the kiln are in oxidation, some reduction, as well as some parts effectively neutral. Likely with methane there is always some water gas reaction. Who knows how long hydrogen can survive in a mixed atmosphere.  There is too much I don’t know.

Wood Combustion

Part of this dynamic and discussion seems very important in wood kilns, particularly long ones. “This is what I see happening.”” This seems in part more like conjecture.” I am going to encode sentences with how certain I am of them. Sentences with fairly high certainties will have one period. Sentences where I am pretty sure two periods.. Less certain, three periods… just a working theory, four…. These are of course approximate. Some things might be substantiated by reading, some by experience, some just because they make sense.

Pyrolysis of wood produces many products. At higher temperatures these include H2 (hydrogen molecules), CH4 (Methane), CO (Carbon Monoxide) , and CO2(Carbon Dioxide) and H2O (water). Charcoal becomes mostly just carbon and ash as pyrolysis progresses. As it becomes more pure it burns more and more only on the surface. 
Before coming into contact with added air, some of the methane and water is going to go through the water gas reaction, CO+ H2O = CO2 + H2  .. This does not really change what is in the mix, just the proportions of it.

So, for me the easiest to start with is the Hydrogen. It is the easiest to burn.. It has the lowest flash point and the highest affinity for oxygen of all the common products of pyrolysis.. It burns first.. Like carbon monoxide its affinity for oxygen makes it an agent for reduction. But these two ingredients appear to have different properties of reduction of glazes.. This  appears to create some of the vagaries of wood fire.

Because of hydrogen’s high affinity for oxygen and its tendancy to burn quicker and easier it is the first to leave the stream. Because of this, it often is not likely to affect the clay. It disappears too quickly by becoming water. But one of its properties differentiates it from carbon monoxide. It is more soluble in glass than carbon monoxide.. Where carbon monoxide either needs to reduce a glaze only on the surface or only before it is melted, hydrogen can effectively penetrate the surface of the glass and reduce materials after they have melted.. This appears to be the mechanism that creates the salmon colored flashing often sought in wood and soda firing.. How this relates to other mysticism relating to the miraculous Avery Kaolin I don’t know. I am certain that Alan Watts must have done a lecture on Avery…

That salmon color seems to require a small amount of volitalized alkali metal. You can get it with both potassium carbonate and sodium carbonate is vapor kilns. It is not strictly a soda color. But introduction of water into a reducing stream of gas appears to increase the amount of salmon color.. I first heard of this from Mac McClanahan in the early 1980’s and then I tested it. It seemed true. Further use of it in my work, and my students has made me more certain..  The year after testing it I was a resident at The Archie Bray and read about the water gas reaction being used to reduce iron oxide in brick and lowering the maturing temperature of pavering block in Archie’s old library. I became a believer.

The next fuel in the mix is CH4. Given enough oxygen this just burns to water and carbon dioxide, just like it would coming from a pipe.  The Hydrogen generally goes to water first but given some existing water some of it becomes hydrogen. This is the part of this that makes me squirm and wonder if the model is correct. Some of it if mixed with air poorly or if the oxygen mix is too low becomes soot and water.  This is part of the reason that firebox design  in wood kilns seems critical. Methane burning with suffient oxygen has a blue color.

Carbon monoxide, just as in gas kilns appears to be the main reduction agent lingering in part, if you are firing in reduction, until it comes out from the kiln. The yellow orange flame at the flue or spy holes, if not the result of sodium flare, appears to be the carbon monoxide burning. Oxy -Hydrogen flames have a similar color but are much weaker in light. This can keep things confused I think. I believe that this color is more towards red, but also has a small component of blue…

It can be really difficult to determine the source of a flame color. It is important in learning to do this to evaluate the hue as this changes by source. There are several different fuels with yellow orange flames.

In a kiln, you only see flame where there is enough combustion to create enough light. I suspect that the water-gas reaction also produces light…

This brings us to carbon, soot, C, is of all of these fuels the hardest to burn. The first part of this is that it just needs a higher temperature to combust. I believe that Cardew states that this is 650˚C and I have seen other reference to 660˚C..  Cold air can extinguish burning carbon.. It also produces less heat per gram. The third is that it tends to clump when it is produced and can only mix with air on its outside layer. It has the ability to lengthen flames if the kiln has sufficient oxygen. Carbon may have an important role in evening the temperature in long single chamber kilns….But soot leaving the kiln is wasted fuel.

I wonder if having multiple stoke ports along with its obvious use in evening temperature also contributes to a bigger distribution of salmon color as it puts the hydrogen closer to more of the ware….

Burning charcoal that has lost its volatiles requires hot air. Since it only burns on the surface it goes away slowly. Maintaining the heat is critical to burn charcoal and this is one of the important aspects of Bourry box kilns. The do this by putting the location to burn charcoal after the production of methane and hydrogen and after where these gases start to burn.






Archie Bray Foundation Front showing bottles by Louis and stack of Gail's

Archie Bray Foundation Front showing Louis’ soda fired bottles and stack of Gail Busch’s in the window. Brick were fired in the brickyard.

 

Mistakes and Innovation

Innovation is often brought about by pressure. You can do something a certain way and it is expensive, so cost pressures you to find a cheaper way. The expense can be time, material, monetary currency, complexity, reliability, lack of beauty. The expense does not even have to be real to pressure you towards innovation. It just has to be perceived.

Early on in my development of my current light installation I had to have a way to turn up and down the levels of light on Red Green and Blue LEDs. The light levels built into my RGB chip that I am using are 0-255 . There are only 256 levels. The problems are that there is nearly no difference between 254 and 255, the lowest levels are not visible, 0,1,2, and sometimes 3, cannot be seen, and the difference between 3,4,and 5 are pretty coarse and that the three colors have different properties. Some seem more linear at lower levels than others. The lowest visible level on each of them is different. Each time you want to adjust one of the levels you change the code and then load it up to the chip. Getting it to look smooth was not difficult, but at the start it was time consuming.

When using a bigger chip with more memory I used three lookup tables for the levels. This is a table that might start like this, [0,2,3,4,6,8,10,13,16, etc.] But for this piece I only had ATTiny 85 chips during the development. Others were becoming available again. The ATTiny has got “Tiny” in its name for a reason. At $1.59 its memory is limited.

Using the lookup tables I started to get “out of memory” type errors when trying to “compile” the program. Compiling is the process where what you have written gets translated into the code your computer, in this case the ATTiny can use. I had to come up with another way. The errors made no sense to me, my program did not use that much memory. But I am not a computer scientist, no degree, no deep expertise. “Live with it, find a new way”.

So, instead of using a lookup table I used multiplication and division of integers. But because numbers with decimal points use more storage, I would multiply by 106 and then divide by 100 then add 1 on the way up . So 30 stepped would step to the integer portion of 30*106/100 +1, or 32. 100 steps to 107 and as you get higher the steps get bigger. Coming down I multiply by a number less than a 100, say 94 and subtract the 1. This does not use that much less memory as far as I could figure, but it worked. Maybe there was something I did not know. I cannot know everything, sometimes I just let things be if they are working.

Well turns out I had tried to compile my software with the settings set for an ATTiny 25, not an ATTiny 85 and it has much less memory. However, the new method is much easier to tweak and keep track up so I have stuck with it. It produces numbers very similar to my lookup tables, mostly because my lookup tables were done by mostly approximating the formula in my head. The formula has a softer top or bright range and I like the way it looks. I ran a single strip of lights back and forth the old lookup table way and the new way. I like the new way. If I go back to a lookup table for some reason I will likely calculate the steps.

The chips I am talking about using in the next piece have four times as many steps. I am about to start working with them. But I think that the properties of LEDs will stay the same so the formulas will stay similar. Since the communication time with the new LEDs is also faster there should be less jitter and flicker. I am excited to see them. With more steps lookup tables become even less efficient and more difficult. The multiplication and division for indexing is much easier.

Notes on printing circuit boards in bulk, single sided,asphaltum, screen printing

Problems in Silk Screening.

  1. Kissing. This would be easier on a vacuum table.
  2. There were multiple places where the screen got clogged. This might have been from hard spots in the asphaltum.

Etching

  1. Etchant was intended to be mixed at 45 grams etchant to 100 grams water. For the 30 205x305mm boards I mixed 1.5 pounds of etchant to 1500 ml of water.  This was 47.6 % roughly oops.
  2. The intial etch was 20 (10+10) minutes. It seemed over done with some areas under the edges etched away. However, this was also the thinnest print so it is hard to know.
  3. The etching was done on my agitator,, a rocker. The container was rotated 180˚ after half the etch because the action of the agitator is not even. Centers etched slower. The fact that the ends of the board finished soonest points to the idea that the first board was not printed thick enough rather than being over etched.
  4. When successful etching times increased to 30 minutes I added about 250ml of concentrated muriatic acid to the bath. This would bring the etching time down to 24 minutes. I did this three times.
  5. Each morning a few tablespoons of alcohol were added to decrease the amount of etching that was clinging to the asphaltum after the boards were removed to keep from wasting etchant. It seemed to work well.
  6. After the first few I started prepping board by lightly brushing etchant onto the slowest parts of the board keeping two boards going through this process as one was being etched.
  7. Another board etching failure seems to have resulted from brushing the center of the board. The margins of the asphaltum were eaten under.
  8. several boards had areas where either the  printing was incomplete or damaged. These were repaired before etching with Zim Opaque Pen. This came off in the etchant about half way through. 
  9. final etching time was about 40 minutes. I decided to let the etchant wear out further so that there would be less to neutralize to recover the iron and copper.

Cleaning

  1. A mixture of about 4 -8 parts  Klean Strip 1-Gallon Odorless Mineral Spirit Substitute   was mixed with vegetable oil. This mix was much better for the initial strip than the mineral spirits substitute by itself. It appears that Klean Strip has either removed the word Substitute from the name or stores have stopped selling this product.
  2. I also tried some water based paint remover. It was not very good by itself but was functional as a secondary cleaner. It was less than optimal there too. It did seem to leave the copper without much oxidation. But given that I intended to soft scrub the copper before plating this was of little import.
  3. A secondary wipe down with the mineral spirit substitute worked better than other things I tried.
  4. Most of the boards were cleaned by pouring a Teaspoon onto the board and spreading it around. Then using a saturated rag often quite full of asphaltum, and light scrubbing. After that a wipe down with a cleaner rag and then used paper towel, then newish paper towel.

 

 

noodles เส้นก๋วยเตี๋ยว

Types of Thai Noodles เส้นก๋วยเตี๋ยว (if there is something wrong here, let me know at my firstname@domain
I needed to straighten noodle types in my head. Many of the words seem descended from Chinese and are hard to remember or pronounce.

  • Gao Lao เกาเหลา is a noodle soup usually served with no noodles.
  • Sen Lek เส้นเล็ก, with translates as little string shaped stuff
  • Sen Yai เส้นใหญ่, see Sen Lek, but big
  • Sen mii เส้นหมี่, this appears to be a rice noodle that is thin
  • Guay Jab ก๋วยจั๊บ These are sheets of rice noodle.
  • Khanom Jeen ขนมจีน . These are noodles made locally with a device that looks like a potato ricer. The rice flour is soaked for 3 days or so before being turned into noodles.
  • Ba Mii บะหมี่, wheat with egg noogles
  • Ba Mii  บะหมี่โคราช, Korat style ba mii noodles. I have no idea what makes them different.
  • Giam Ee เกี้ยมอี๋ These are a thick short rice noodle with pointy ends. The Chinese names are quite colorful https://en.wikipedia.org/wiki/Silver_needle_noodles . I do not think that I have had them.
  • Woon Sen วุ้นเส้น are made with mung bean flour
  • Ma ma มาม่า , บะหมี่มาม่า or ramen is a brand name of ramen noodle but it is a word used generically for ramen.
  • Gouitiow ก๋วยเตี๋ยว This seems to be a type of soup rather than a type of noodle. I find it tremendously hard to remember how to pronounce.
  • Khao Soi, is a dish that is different in different places. But in Northern Thailand it usually has fried rice noodles. But the name is for the dish, not the noodle.

Ethnocentrism and Flux

This seems an essay rambling through topics. Structurally it is all about the models we view the world with, their limitations and the power of stepping to the side and gaining perspective. In this the word “flux” refers to a group of ingredients and related concepts in glaze and clay.

Probably the single most important lesson I had in school was one on the word and concept “ethnocentrism”. I believe that the class was in fourth grade. It could have been fifth. I grew up in a suburb of Detroit, a “shtetl”, an area where greater than 90% of the people had Jewish ancestry. I believe that the word was part of the curriculum for that grade as others I have talked to had similar lessons. Its inclusion, not having anyone to ask about it, seems likely the result of, a response to, antisemitism, The Holocaust,,, ongoing problems. Cities near us did not allow Jewish residents, pools were segregated. For me the lesson on ethnocentrism was critical to my development. Having lived in many parts of the US I wish the lesson was more widespread.

Ethnocentrism is the concept that from within a cultural viewpoint the actions of that culture seem consistent, meaningful, sensible and from outside the culture they can seem otherwise, bizarre, random, nuts, etc. The concept states that our feelings of our culture and that of others are framed, guided, by our cultural standpoint. Ethnocentrism has its strongest expressions in monolythic cultures, but certainly exists in multicultural environments. It is often, maybe always, a root cause of “isms” such as racism, ageism,  nationalism, religiocentrism, etcetera-ism. 
The lesson  and the thoughts related to it tied itself over the years to many different topics in my daily goings on. So many that it now seems like it is part of every day, every thought, every moment,, connected, a sinew atttaching my hair to my toenails, my thoughts to my emotions.

At the University of Michigan in a course in The Pilot Program, a living/learning environment/dorm/community at Alice Lloyd Hall I took a class called “An Overview of Low Energy Technology” taught by a multi-talented individual, Jim Burgel. One of the requirements, seemingly unrelated to this course, was reading, “Zen and the Art of Motorcycle Maintenance”. This book, although seemingly on a different topic than ethnocentrism melded into this topic. In some ways the book is about how our concept of the world changes how we perceive it, and how there are different ways to conceptualize the world. The differing rationalities described in this book seem consistent from the inside. It is a discussion of rationality and how it creates the lens through which Western Civilization views the world.

At the same time I was taking an Art History Survey course, “An Overview of Far Eastern Art” History taught by the late great Professor Walter Spinks. In it, at the beginning of each section, he tried to give us an overview of how a people perceived the world, what concepts guided their thoughts. I remember much of what he said about Taoism. I found it captivating. Later in the semester we discussed Buddhism and Zen Buddhism, and the illusory nature of perception and confusion of it. perception,  with reality. Over the years it took hold. An interesting look at this is contained in The Jews in the Lotus, by Rodger Kamenetz. The book is a discussion of the events leading  up to a meeting between a group of Jews and the Dali Lama. The Dali Lama was trying to understand how a people can live and thrive in exile and wanted to talk with experts.

But in the book there is a short discussion of JewBu’s, Jews who become Buddhists. There seems to be a lot of these. It seems, although hard to quantify, that the Jewish mindset meshes well with Buddhism. I do not have any great insight on this. I cannot step far enough out of my own box to gain perspective. The one idea that I do have is that both frameworks are very abstract. But it seems that  belief is generally not as confused with knowledge as it is in the culture of the US. This appears to fly in the face of rationality, but people, cultures, are not consistent with themselves. They only appear to be.

So, what does this have to do with “Flux”?
The word has many meanings, lots of definitions, and exists in many realms. But this discussion is its use in Ceramics. There are lots of definitions, complications,  overlaps, inconsistencies in how ceramics melt and sinter. The word and concepts are not simple subjects.

Perhaps the most general definition is, “A flux is a chemical that promotes melting”.  Great! It is a nice concept. It apparently is descriptive. It has nice defined edges. Something that does not promote melting is not a flux. 

As you add say calcium oxide to a clay body or a glaze that has none it melts easier and easier at a lower and lower temperature. The problems are that there is a lower limit below which it does not seem to help the melt, or at least not much. There is also a limit of the material above which it does exactly the opposite, prevent melting.
The relationship, and the problem with the word “flux” as it is used here is best illustrated with calcium oxide (calcia), aluminum oxide (alumina) and silicon dioxide (silica). These three ingredients form a nice looking stoneware glaze and sit close to some traditional celadon recipes from China. If you take the lowest melting composition, you can mix a recipe close to it it with one part of kaolin clay, one part ground quartz sand, and one part limestone. It simply demonstrates  the complexity. The limestone is traditionally called the “flux”. But if you remove or just lower the alumina the melting temperature goes up. Alumina in this composition helps the melting. It is by this definition a “flux”. The same thing is true of silica. As you remove the silica, the melting temperature goes up. It fluxes the alumina and limestone. It helps them melt. As you remove the limestone, the same thing happens. Each of these materials fluxes each other. Understanding this is critical to understanding glazes.
So the next most useful way to pidgeon-hole materials is to remove the silca and call it a glass former and alumina as a stabilizer or amphoteric. This makes the definition of a flux something that helps the alumina and silica to melt or sinter. This makes a lot of sense. It is unusual for us to add silica to lower and melting point. Normally what we seem to recognize and encounter is that adding it to glaze, after a certain point, raises the melting temperature. Alumina starts raising the melting temperature in much smaller quantities. But at temperatures down to the very low temperatures for glazes, little bits of alumina lower the melting points.
Hermann Seger developed the modern pyrometric cone,  a device for measuring the temperature and time components of the melting of glazes. Little tall cones of glaze materials, “cones” are made of the materials used for making glazes. At certain temperatures, after a certain amount of time they begin to melt and slump over. The can be spyed, throught what in the US is called a spy or peephole to determine the maturation of glazes in a kiln.
In doing so, he developed or at least further developed a system for analysis of glaze, still used today, called the “Unity Formula”. Rather than opperate on weights of materials, the unity formula uses counts of molecules, or moleclar equivalents in the glaze.
The unity formula is divided into three columns. The first is “The Fluxes” the second is “The Glass Formers”, the third is the “Modifiers” or amphoterics. But as simple as this seems, it too is an oversimplification, and some call the first column RO/R2O meaning items that take the form of an atom or two of a metal (R)  and a single atom of “O”, oxygen. The second column is the RO2 (one metal two oxygens) and the third is R2O3. Fine.
The material whose fit is seems the worst is Boric Acid, B2O3. By formula it should exist in the modifiers. But we add it to lower the temperature of melting, a flux, but it forms glass by itself and is a glassformer.  Most of us have left it in the third column but it needs to be thought about on its own.
We used to have a fourth grouping, “colorants”. Some of us still use this grouping. These are things that we add to glazes to change hues, or to add hues. The problem is that most of these materials also  act as fluxes, or help lower the melting temperature of the silica glass. Some of these exist in different forms depending on the temperature and composition of the gases they are melted in.  Some can loose oxygen as they are heated, some loose some of their oxygen if heated in a gas containing carbon monoxide or hydrogen, and some change how they function depending on their quantities, really all of them do. In terms of how they affect melting most of them belong in the fluxes. Some don’t and are glass formers.

I think that flux,glass former, amphoteric, is fine to a point. But thinking of things as melting is a limitation. Sure, they melt. But once we have a liquid using the vocabulary and concepts of solutions is much more informative. A solution of alumina silica and calcia above its melting point has an infinite ability to dissolve feldspar. Its ability to dissolve baria is limited, as is its ability to dissolve chrome oxide. At some point the solution gets saturated. Generally speaking in a saturated solution once the temperature starts to drop, things can crystalize out of solution if the mix does not become super saturated. This concept, solution, contains the complexity that happens as you add calcia to a  melted glaze.

Like many other things involving the definitions of words, “what is a flux” can become a turf war, especially between people who see the word or words as a real map of reality. For those, the word gets confused with the hopelessly complex reality. I too can get caught in this trap. I am not sure who does not or cannot. If the Buddha, the “all knowing and aware one” exists, than I suppose, again by definition, they are not confused. My belief is that the only real model for how the universe works would be another universe. I find more resonance in knowing how things flow, the patterns they make. This relates more to Taoism.



Words, the concept of them create a box from which we see the world. We define colors, speeds as fast or slow, temperatures as hot or cold, objects are cars or boxes, we create our world with our words and concepts.
Because of this I have a tendency to “dedefine words”. Art rather than being on object made by an artist, becomes “any object of intelligence”. But even this is not as broad as my real desire, nature too is art. So every object, idea, concept is art. Art is everything. It just become another “everything word”. It describes a particular set of glasses through which you view existence. The other problem in the “object made by an artist’ is that I define everyone as an “artist”. Everyone is expressive, everything the do is expression, and creative. 

Now there are ideas in the West that embody at least part of this connected all/everything. I call these ideas, or box them in, with the concept “everything words”. We here these all the time. “Everything is G-d”, Everything is Love, Everything is Chemistry, Everything is Physic, Math, Science, Psychology. And inside my box, I see everything as Art. The truth here seems to be that everything is everything.  But I find that I need to qualify this, Everything is Everything except when it is not.

คืนรัง คาราวาน หงา Nest, Night, sung by Nga (Sesame Seed) Caravan, also ขอมอบ ดอกไม้ ในสวน

With help from google, an old Caravan song I can now understand more completely. I have been listening to it for nearly 40 years and understanding more and more. Its time to put some work into it.
ด้วยความช่วยเหลือจาก google เพลงคาราวานเก่า ๆ ตอนนี้Louisสามารถเข้าใจได้อย่างสมบูรณ์มากขึ้น

คืนรัง คาราวาน หงา

โอ้ยอดรัก ฉันกลับมา
my dear I’m back
จากขอบฟ้า ที่ไกลแสนไกล
from the edge of the sky, the horizon, far far away
จากโคนรุ้ง ที่เนินไศล
from the bottom of the rainbow at the base of the hill
จากใบไม้ หลากสีสัน
from various colored leaves
ฉันเหนื่อย ฉันเพลีย ฉันหวัง
worn, tire, I hope
ฝากชีวิต ให้เธอเก็บไว้
to give her life to keep
ฝากดวงใจ ให้นอนแนบรัง
leave your heart to keep, sleep in place of comfort?(nest)
ฝากดวงตา และความมุ่งหวัง
leave your eyes and hopefulness
อย่าชิงชัง ฉันเลยยอดรัก
do not abhor me, I am so in love.
นานมาแล้ว เราจากกัน
long ago we parted
โอ้คืนวัน นั้นแสนหน่วงหนัก
that night was heavy and painful
ดั่งทุ่งแล้ง ที่ไรเพิงพัก
like a dry field where nothing rests
ดั่งภูสูง สูงสุดสอย
as the mountain the highest mountain
โอ้ยอดรัก ฉันกลับมา
oh my love I return
ดั่งชีวา ที่เคยล่องลอย
like a life afloat
มาบัดนี้ ที่เราเฝ้าคอย
Come, this is what we await
เจ้านกน้อย โผคืนสู่รัง
the little bird flies back to the nest
นานมาแล้ว เราจากกัน
We parted long ago
โอ้คืนวัน นั้นแสนหน่วงหนัก
Oh a night so heavy
ดั่งทุ่งแล้งที่ ไรเพิงพัก
like a dry field where nothing rests
ดั่งภูสูง สูงสุดสอย
as the highest mountain
โอ้ยอดรัก ฉันกลับมา
My love, I return
ดั่งชีวา ที่เคยล่องลอย
มาบัดนี้ ที่เราเฝ้าคอย
like a life afloat
เจ้านกน้อย โผคืนสู่รัง
a little bird flies back to the nest
ฉันเหนื่อย ฉันเพลีย ฉันหวัง
I am tired, I am weary, I hope

https://www.youtube.com/watch?v=ssOvl5WM_0s UNICEF Concert Album (I think)

https://www.youtube.com/watch?v=hCA2aaMHFOs หงา คาราวาน (Official Audio)

https://www.youtube.com/watch?v=G-48LT-swQE Thai PBS

https://www.youtube.com/watch?v=UXFdVi3Zvok Khon Dankwian (Lyrics)


https://www.youtube.com/watch?v=G-48LT-swQE Thai PBS
https://www.youtube.com/watch?v=JnX3weyNPr4 ปู พงษ์สิทธิ์ คัมภีร์

https://www.youtube.com/watch?v=EeRiI1E9GVU Orawee Sujjanon


https://www.youtube.com/watch?v=7VoLhFpUWfoSek Loso

 

Flowers from the Garden
ขอมอบ ดอกไม้ ในสวน
I offer, I ask  the flower from the garden
นี้เพื่อมวล ประชา
for the people, the publci
จะอยู่ แห่งไหน จะใกล้ จะไกล จนสุดขอบฟ้า
for you where you are foreverขอมอบ ความหวัง ดั่งดอกไม้ ผลิ
I offer, I ask, for you hope, as in a flower

สด ไสว งาม ตา
Fresh and bright, eyes of beauty
เป็นกำลังใจ ให้ คุณ
to give you encouragement, motivation
เป็นกำลังใจ ให้ เธอ
to give you dear motivation
เป็นสิ่งเสนอ ให้ มา
this is the offering given

ดวงตะวัน ทอ แสง
sunshine
มิถอยแรง อัปรา
there is a retreat
เป็น เปลวไฟที่ไหม้ นาน
Its a long burning flame
เป็น สายธารที่ชุ่ม ป่า เป็น แผ่นฟ้า ทาน ทน
t’s a stream that’s wet, a forest, it’s the sky, enduring

ดวงตะวัน ทอแสง
sunshine
มีถอยแรงอัปรา
there is a retreat(?)
เป็น เปลวไฟที่ไหม้ นาน
Its a long burning flame
เป็น สายธารที่ชุ่ม ป่า เป็น แผ่นฟ้า ทาน ทน
It’s a stream that’s wet, a forest, it’s the sky, enduring

ขอมอบ ดอกไม้ ในสวน
I offer, I ask  the flower from the garden
ให้หอมอบอวล สู่ ชน
to let its fragrance crash ????
จงสบ สิ่ง หวัง ให้สม ตั้งใจ
Something about hope conscientious?
ให้คลาย หมอง หม่น
calm down, chill?
ก้าว ต่อไป ตราบชีวิต สุด
move forward towards life’s end
ดุจ กระแส ชล
like the flow of fresh water (lakes, streams?)
เป็นกำลังใจ ให้ คุณ
I give you encouragement
เป็นกำลังใจ ให้ เธอI give you encouragement dear
เป็นสิ่งเสนอ ให้ คุณ
เป็นกำลังใจ ให้ คุณ
เป็นกำลังใจ ให้ เธอ
เป็นสิ่งเสนอ ให้ คุณ
เป็นกำลังใจ ให้ คุณ
เป็นกำลังใจ ให้ เธอ
เป็นสิ่งเสนอ ให้ คุณ
เป็นกำลังใจ ให้ คุณ
เป็นกำลังใจ ให้ เธอ
เป็นสิ่งเสนอ ให้ คุณ..

 

Collected notes.

“Wirasak Sunthawnnsi (taj. วีระศักดิ์ สุนทรศรี, ur. 24.07.1950 r. – Bangkok, Tajlandia – zm. 17.12.2021 r. – Prowincja Samut Prakan, Tajlandia) – tajski gitarzysta i wokalista. Jeden z założycieli rockowego zespołu Caravan, dziś określanego mianem kultowej kapeli rockowej Azji Południowo-Wschodniej. Caravan jest muzyczną wizytówką Tajlandii lat 70., 80. i 90. XX w. Poniżej grupa Caravan w nastrojowej balladzie „Khon Phu Khao”. Wirasak Sunthawnnsi (Thai: วีระศักดิ์ สุนทรศรี, born July 24, 1950 – Bangkok, Thailand – died December 17, 2021 – Samut Prakan Province, Thailand) – Thai ski guitarist and vocalist. One of the founders of the rock band Caravan, today known as the cult rock band of Southeast Asia. Caravan is the musical showcase of Thailand in the 1970s, 1980s and 1990s. Below, the group Caravan in the romantic ballad “Khon Phu Khao”.”https://zazyjkultury.pl/world-music-ostatnio-odeszli-od-nas-2022/

Clayers Like it Hot!

Clayers like it hot. We just need the heat to be inside the correct box.
Ice Point
This short essay touches on a lot of things, I will try and get it in a good linear organization.
Thermocouples work because metals exposed to differing temperatures in different places develop a voltage between those two places. Different metals produce differing voltages. So when you take say a chromel wire and an alumel wire and connect on end at the other end you will have a voltage dependent on the temperature at each end. These voltages are not linear. So if the meter end is at 70˚F and the connected end is at 170˚F you get a slightly different voltage than if cold end is at 75˚F and the hot end at 175˚F.
Further, if your two connections at your meter (you meter is almost certainly made with copper alloy wire) are at different temperatures you get two more thermocouples at the meter throwing off the measurement. Thermocouple wire, chosen to match the properties of the thermocouple usually connect the thermocouple to the meter (unless the thermocouple is directly connected).
The standard temperature for the end by the meter is 32˚F(0˚C), known in this context as the “ice point”. In order to get accurate readings you might have once placed this connection, watertight, in a bath of icewater. For years meters had electrical compensation for this temperature to make the meter read as if it were at zero. This was refered to as “ice point compensation”. Newer quality meters read the ambient temperature with a thermistor and compensate digitally. Cheaper meters assumed that they were at a particular temperature say 75˚F.
Old analog meters with a needle dealt with the non-linear aspect of thermocouples by printing a scale that was also not linear. Some parts of the scale had lines drawn closer together than other parts of the scale. It was a clever, inexpensive way to deal with the non-linearity.

Because of compensation, kiln control boards likely have on-board temperature sensing. Once they have that it is trivial to design a board to turn the kiln off if the ambient temperature is too high. In the US, having the means to turn off a malfunctioning kiln or kiln operating at an unsafe temperature is a liability issue. It also can vastly reduce kiln lifespan.

Derating of Electronics
Most electronics is designed to operate at or near room temperature. Cars use specific components that are vibration and heat resistant. The military and NASA have their own set of requirements. As you raise the ambient temperature the amount of current a device can take at one time and its lifespan falls. Even if a device is rated at say 120˚F it may fail sooner if operated or stored that hot. It also might need a larger heat sink (piece of aluminum designed to dissapate the heat).
Every electronic and electrical component in the kiln has a temperature rating. Just like elements fired at a higher temperature, power cords, relays, outlets, and control boards are going to fail sooner if operated at a high temperature. Circuit breakers trip sooner in hot weather too. Further as things get hotter, corrosion speeds up.
***Entropy discussion fits here.

I do not know exactly at what temperature Skutt Control Boards give a high ambient temperature warning, but I expect that the boards themselves are already above 100˚F. Heat gets to the control board a lot of ways, but there is insulation blocking much of the radiated heat, openings for convection, and little washer like things between the red box and kiln shell. Still the red box does heat up and consequently so does the control board. You can place a small fan to blow through the control box, something like an old computer fan, not a box fan. You want to avoid fans blowing on the kiln case.
Things that can be done to limit the heat in a kiln room. Open it up, windows, doors, fans in doors. Fire at night (make sure that you do not sleep in a house with a firing kiln). Start early in the morning. Fire faster so that less heat gets out of the kiln before you are done. Fire so that the hot part of the firing is in the evening if the outside temp is greater than 100 during the day.
My insulated studio gets warm in the winter with 1000 watts of heat. Your kiln say drawing 40 amps at 240 volts is just under 10,000 watts. This is a lot of heat and your air conditioner might not want to keep up with it. Plan ahead.
Please do not hang out in very hot kiln rooms and drink enough water. But make sure, especially in hot environments that you monitor your kiln.

Beat Frequency

I thought that I should write something on the development of my new piece, “Beat Frequency”, what its roots are, how it came into being.
I grew up in a musical family. We sang, played musical instruments, I played violin. In order to tune a violin to pitch with a pitch fork or some other stable frequency source you play the violin at the same time as the source. If you are off by 1hertz, so if your pitch fork is for A440 and your violin is at A441 then when the peak of the wave forms happens to hit your ear at the same time it is louder, and when one source is high and the other low, it is softer. This gives the sound a wah wah happening every second. As you tune closer in frequency the wahs happen less frequently.
My father, may his memory be a blessing, built harpsichords. He taught me to tune them. For a short while I could do a reasonable job with just a pitch fork. This is more difficult than it seems because a tempered scale where all the intervals seem reasonably in tune, requires that you actually tune intervals a little imperfectly. Its kind of like walking around a circle with a diameter of 4 feet one foot at a time. When you get to the end, you are going to be a little off, so if you stretch a bit a walk a hair over a foot at a time, no one is going to notice, and you will end in the right place.
I sang. My favorite music to sing was madrigals. They are sung by small groups of people. In my opinion they are best as entertainment for the singers. Singing facing each other in a circle is optimal. In order to do this well there needs to be give and take between the singers each allow each other openings when their singing line should be dominant. You hear this give and take in Jazz or other folk music too.
In my first Art History Class, an overview of Asian Art History, at The University of Michigan, taught by Walter Spink, we were taught about Taoism and its symbolism in Asian Art. The story associated with this was that a man, in tune with the Tao dropped his towel on the side of a river and walked upstream to a bridge where he stripped off his cloths and through himself into the raging torrent. He washed up by his towel where he dried himself off and then walked back to the bridge to get his cloths.  Rivers, and images of water, are often statements about the order, the nature of the universe, of ebb flow, give and take.

Most of us learned prime factoring as children. You take some number and find all the prime numbers that it can be divided by. For example, 165 can be divided by 3,5, and 11. If you have waves a 3,5, and 11 hertz, cycles per second, they will only all come together every 165 seconds. In tuning this would mean that the strong beats happen only every 165 seconds, but that there could be weak beats at multiples of 3×5 (15 hertz), 5X11 (55 hertz) and 3X11 (33 hertz). I use this phenomenon to program the lights so that their effects repeat very infrequently. My math teachers would be happy.
I took electronics in High School. Mostly I learned what was taught. When we got to AC I was very mystified. I really lacked the ability to concentrate enough to gather all that was necessary for understanding at once. I still struggle with this, but I do know what I should have learned back then. It gave me enough understanding to make moving forward with the electronics I need for these lights, and also for ham radio, not too much of a challenge.
I also took computer programming in High School. We did not learn that much, and similar to electronics when we got to assembly language I was mostly lost. But I produced some programs, learned some basics and it has been nice to have this skill. Back then, programs were put onto cards and encoded with little holes that were read by shining a light through them and detecting where on the cards the light past through them. The machines that made the holes were call “keypunch machines”. You hit a key and it punched hole[s for a letter or number]. In general, you put one command, or one program line, on a card.
Our teacher would on Fridays take our cards down to a local university and get them run on their computer. On Monday she would pick up the printouts, the only output from our work, and bring them too us. For all intents and purposes, there were no terminals with video screens for us to use. I did not see one until two years later when I attended a big university.
After leaving engineering school I started doing Ceramics. I was interested in pottery. I was not driven enough by pottery to stick with it, although I did pick up some skill. More than this specific media and product I became interested in designing within constraint. People think of constraints as limitations, but they create a liberation. Without constraint there is no way to start to do anything. This was covered in Robert Pirsig’s book, “Zen and the Art of Motorcycle Maintenance” under the heading of “Stuckness”. Unable to start an essay describing downtown Bozeman, a student thought that they had nothing to say. Pirsig told them to start at the top corner of a particular building. This allowed them to get started. Not only was this a constraint, but a particularly specific one.
I like wood fired ceramic surfaces and also its relative, vapor glazed surfaces. They are most often brown. A colleague who worked in cast iron thought that we should have an exhibition entitled “Brown”. There is an infinite amount of variety in color and room for expression and other content between two shades of brown. The limitation, is not a limitation. It starts a conversation.
My work, my art work, for the better part of 40 years, seemed to revolve around expressing the area of thought between words, pointing out the constraints that language imposes on how we think. What is Function? What is not? What is Functional Ceramics, what is not? What is Art? Where are the edges of these words and meanings? Do they exist? I am not sure that my study of Far Eastern Art, and the need to learn some about Taoism and Buddhism started this inquiry, but it informs it. The world defined by words is illusion. Words are an abstraction of reality as are photos, video and sound recordings.
Starting in the late 1990’s I started making videos about these ideas. The first was about Art History. The definition of Art used in the academy and particularly in Art History is narrow, limited, and ethnocentric. While what is show in Art History course has expanded, it is most still seen through a lens that remains unchanged. Movies continued. There were ones about what Ceramics is, what Art is, and why woodfiring is important. They were really about philosophy, but also about beauty and fun along with other things.
One aspect about many of them is that they had two audio and video tracks (or more). These tracks became dominnent and then stepped back in the same manner as the madrigal music I like, or like waves at different frequencies. They beat. There is and was crescendo, and decrescendo, give and take. I loved playing with the stereo. Two related discussions seemed to capture the thoughts of viewers.
Sometime in 2011 I bought an Arduino. This is a microcontroller development platform, a small programmable computer used for developing microcontrollers for embedding in simple devices like thermostats, drones, three d printers and my lights. I really had no idea what I was going to do with it, but a student asked me how to make a switch turn on a device with some specific timing and this device seemed the easiest way to do it. I got up to some basic speed with the device quickly. I had the right set of skills and experience. The platform, Arduino, was designed to allow, to create a space to learn, allowing non-technically trained microcontroller experts to develop applications.
Lady Ada and Adafruit
Adafruit, run by a fantastic innovator who goes by the name Lady Ada, sells parts and supplies, boards, and really education in part for people using Arduinos. She got started in college. Frustrated by having to wait for electronics to arrive, she stocked parts and sold them to other students out of her dorm room. Its a fantastic company. I do not think that I ever would have succeeded in making work with the Arduino without her and without companies like hers. She manages to have a manufacturing plant in New York City.
The digital revolution has brought an amazing plethora of opportunity. My early lights required that I build circuit boards by hand. My small hand skills are not great. I am not neat and clean in small detail. In the modern world I would be diagnosed with Dysgraphia, and likely some small motor skill deficit. I have managed to survive and flourish despite it. But, one day I just became ill over the idea of building another board to control my lights and said to myself, “whatever the cost, I am going to have these boards made for me”. So like any modern person, I went to Youtube to find out how to do this.
On a Monday Morning I watched 39 minutes of video instruction on using an open-source program for designing circuit boards for production by a factory in China. On Tuesday, I designed my board and was finished before noon. Wednesday morning I checked the design and uploaded it to the manufacturer and made my payment. A week later Wednesday at around 5 pm my 5 custom printed boards were delivered to my door. The total cost was about $13.50 including shipping. I should have done this sooner.
Those were just the boards, and I had to solder everything onto them. Now I am getting most of my parts place by robots. Doing this allows me to not pay several layers of markup on individual parts and is actually cheaper than assembling myself. Also many of the parts are too small for me to reliably solder to my boards with my current skill level and equipment.
The boards are essential screen printed. A block is printed onto both sides of a fiberglass board sandwiched between two thin layers of copper. The board is etched until the exposed copper is gone, leaving copper only where there is a block. Holes are drilled through the board. The board is then screened again with another block and then it is plated with solder including the inside of the holes. Both sides are printed with whatever text or marking you design into the board, the board is tested, cut out, and packed for shipping. When getting robotic assembly, this comes just before shipping.
Etching a circuit board uses the same process as etching a plate for an intaglio print. My boards I am having assembled are small. In this piece they are about 1/2 inch by 8 inches. I am using a 9″x 12″ one sided board that I designed (Maclovio Cantu taught me how to etch the board) that was etched in a bath of ferric chloride. This board is the base that everything else is mounted on. The traces of copper on this big board are decorative, but also constrained by needing to provide power to my small boards. There are six small boards used in this piece, three on the front, and three on back.
I am having some technical issue that I have to solve before I sell work like this. Likely this will involve some design constraints. It is easy for this to seem depressing, a hassle, etc. It is more productive to think of it as more opportunity. Dealing with the constraints causes growth.
Beat Frequency uses six of the twenty five boards I had printed and assembled early in December. I also let the smoke out of one. “Letting the smoke out” really means burning out the parts, overheating chips until they smoke. I hooked it up backwards. The 25 board cost about $130 dollars. They took a full day to get ready for production and are based on the work done on three other boards. The board before them was quite similar.
This board uses a microcontroller called an ATTiny85. They cost about $1.59 and are again available. I would prefer using the ATMega 328P-PU. I have some on order and expect to get them in May. I bought a stack of the ATTiny85’s at the beginning of the pandemic so I would have some. The 328’s are more powerful. One could run the hole project. Instead I am using 4. On the back the top and bottom board uses only one board and the right and left lights on the front are similarly linked.
This short essay [was posted] unedited. Nor did I go through and correct spelling, grammer [(left on purpose)] or other mistakes. I am going to post it before editing, and if needed will correct and encase the corrections inside [brackets]. I did write an outline.

Controlling Glaze Application Thickness on Porous Bisqueware.

Controlling Glaze Application Thickness on Porous Bisqueware.

Factors controlling the thickness of a glazecoat on bisque.

  1. Length of time in the glaze
  2. Density of the glaze suspension. That is how much water is there and how much suspended powder.
  3. (Apparent) porosity of the bisque, including how dry it is, how much pore space it has, how quick the pore space absorbs water, and how thick the bisque is.
  4. Rheologic properites.
    • a. flocculation
    • b. surface tension and viscosity
    • c. number of long molecules (might be covered in viscosity)
    • d. The amount of fine particles that can clog surface pores.

Length of time in the glaze

When you dip a piece in your glaze suspension the bisque ware starts to absorb water first making the glaze near the surface a more dense liquid and then turning it solid. So long as the bisque is absorbing water fast enough the glaze coat continues to thicken. As the absorption slows down there reaches a point where the coat of stiff glaze starts to get wetter again and slough off. The thicker the work is, the thicker the glaze can get and the faster it gets thick. In beginning thrown work the base of the pot is often thicker than the top making the glaze thicker near the bottom, just where running has the biggest likelihood of causing an issue.
Dipping the work in water before glazing decreases the availability of pore space for absorbing glaze. Right after you dip it the effect is greater. Because water without glaze absorbs quickly these have to be very fast dips. With work that is thicker near the bottom you can dip the bottom few inches in water before you glaze and if needed pour a little water on the inside bottom and pour it out. I do this with really runny ash glazes so that they will not run too thick on the inside.

How long a pot is in the glaze is perhaps the primary method of control of glaze coat thickness. If you imagine pushing a cylinder in for 5 seconds and then removing it for five seconds, the first part of the pot to enter the glaze will be in the glaze for ten sends and the last for less than a second. If you want an even coat of glaze, you will not have it. I use the words plunge, wait, pull. Don’t go so fast that you create a tidal wave or splash but do not take your time putting the pot in, or taking it out. After you pull it out you usually want to keep it in the same orientation so that you do not get drips down the side of the pot.
If you are doing two different glazes, the amount of time you wait between glazes controls the thickness of the overlap. The longer you wait, the drier the first glaze becomes and the more porousity it has avaialble to dry the second coat of glaze. Being ready with the secoond glaze saves loads of problems. As soon as the high sheen is gone it is usually safe to dip in the second glaze.

Density

More solids in the glaze means that the pot has to absorb less water to make a stiff coat. This speeds up how quickly a coat accumulates. Adding water can work to a point but it also increases the shrinkage of the coat as it dries. With too much water sharp edges of the clay become saturated and get little or no glaze. There are many ways to test the thickness of a glaze coat and to control it. The first measure of control is the density. How much does a given volume weigh? Adjusting that by adding water (it decreases the density of the glaze) is the first thing to do after checking if it is too dense.
Glazes should be stirred immediately before glazing. Some glaze mixtures are particulary sensitive to this. Further, since materials settle out at different rates an unstirred glaze is a different glaze at the top than the bottom. There is a particular watery look to the last part of a pot dipped into an unstirred glaze.

Rheology

The rheology of the glaze is the next issue to deal with. As you speed the absorption of the water needed to stiffen the coat and as you reduce the water needed to be absorbed you cut down on the space between the particles of glaze. At least this is the theory of Matt Katz, and it makes sense to me. This decreases the amount of air that will be trapped in the melted glaze coat and cut down on pinholes. Adding a deflocculant helps with this as it reduces the amount of water needed to make glaze fluid. Shorter dipping time also helps. Matt also favors low bisques because it increases the force and speed of water absorption decreasing the pore space in the glaze coat.
On the other hand flocculants seem to cut down the amount of thickness variation created by drips flowing off handles or bottoms of pots when they are pulled from the glaze slurry. Since you cannot deflocculate and flocculate at the same time, you have to do what is needed more depending on the glaze.

Fine Particles

Fine particles, especially bentonite, also help to keep drips from setting in thick streams. The fine clays clog the surface pores as the pot is held in the glaze. So once the glaze reaches a certain thickness the rate at which it absorbs water slows down decreasing the impact of drips as you are applying glaze. It is a good reason to add bentonite to most any glaze. Veegum does this too. Glazes with lots of ball clay do not need the addition.
Other additives such as gums, glycols, can slow absorption even further. Some of these materials affect the rheology in multiple ways. They can be deflocculants, or flocculants, they can affect the surface tension or viscosity so test them. Make sure that your kiln is vented regardless and avoid things that you should not have your hands in or are hazardous to burn.

Ways to check glaze thickness

  • Scratch through the applied glaze with a pin tool and look at the thickness of the coat.
  • Look at the glaze coat and see how it covers details,rounds off rims,  and look the thickness at the edge of the coat. This is harder than it seems and takes practice.
  • Make a thickness gauge out of a dial indicator. I am hesitant to give directions as I have not used one.
  • Make a thickness gauge out of a piece of metal with a series of teeth that will scratch into the glaze coat. I believe that I read about this in Cardew’s “Pioneer Pottery” but it could be Leach’s A Potter’s Book”

 

In order to do this you need some vocabulary, a mental scale of thicknesses. Although if you are using a dial indicator a numeric scale might make sense.

  • Light Wash. A thickness where you see more clay than glaze. The wash is only thick in recesses if anywhere at all. Likely it does not show at all on sharp edges.
  • Heavy Wash. The coat mostly covers the clay but you can see some clay showing through on flat areas of bisque. Usually it is thin on sharp edges.
  • Just Opaque. A little heavier than heavy wash, you cannot see the clay on flat areas at all although edges may show.
  • Photo Paper Thickness
  • Half the thickness of a dime
  • The thickness of a dime
  • Penny
  • Nickel (US or Canadian coin)

Boat Duck Noodle Soup

ก๋วยเตี๋ยวเรือ Boat Noodles

“Louis, What do you want for dinner?” This was the question my Thai friends, for all intents and purposes, family, asked me.  I requested Duck Soup with noodles. It was special, I was just getting to town. The only places they were sure had Duck soup were not open yet. Once I said duck soup it became the objective. Two hours later, no matter how much I said, “lets find something practical”, we were still looking for duck soup. My family there is 180 degrees out of phase with “practical”.

Soup with rice noodles ก๋วยเตี๋ยวเรือ kwuaytiyo rya  is a common street food throughout Southeast Asia. In Thailand it is often sold by vendors with pushcarts, and folding tables and chairs. I particularly like the duck variety although I often eat the pig variety or chicken. เรือ Rya means boat and these were traditionally served from boats on the canals and river in Krung Thep. The first part of the name appears to be Chinese or Malay, I am not sure.

It is hard to understand how important food is in Thailand. Even a rushed lunch location is an important decision. There is almost always a sauce, or three, available and often there is customization, do you want innards or not? Extra meat? The special version or regular? And then in places you can ask for all sorts of things. Some dishes always come with the same garni and/or condiments. A few dishes always come with clear broth.

But kwauytiyo is relatively simple except that I can never hang onto how to say it. You can order it without liquid, but it normally is with broth. You get to choose the kind of noodle in most places.  Normaly you would get rice noodles. But even these come in three plain varieties, wide, small, and round, There are flat 2 inch square noodles served in other dishes. Then there are bha mii, a wheat noodle with egg, woon sen, a bean thread, and mama noodles, the instant ramen noodles.

Where I stay in Thailand there is a noodle cart permanently parked on the sidewalk by the bridge over the highway. These bridges are called floating spans. Anyhow this cart is only open nights. I suspect that the owners use it to suppliment income. They only serve the pig variety. In my opinion it is pretty plain, but makes a great 10pm snack.

The meat is usually inexpensive cuts sliced thing. In first quality beef soup there is usually some tendon. It helps make a great broth. There are often “fish balls” or other protein concoctions, usually round. There can be liver. Since it is not broiled, this is something I usually do not have a big problem with. A friend commiserates with me about liver, he says he would rather eat the oil filter. I can relate. If the dish is served in a fish variety it is usually with luuk chin pla, Thai gefilte fish.

I cannot speak to to the seafood version of kwautiyo I never order it. I seem to be the poster child for food poisoning from clams. I stay away.

Namtok, meaning I believe “waterfall” at least literally refers to adding blood to the broth. This makes it much richer. It is not always available.  If you are European they might assume that you do not want it.

Once you get it on the table you have condiments to fix it up. There is Naam Pla Phrik or Fish sauce with peppers, usually there is some coarse grind of red pepper, sugar sometimes, salt, plain fish sauce and ground white pepper. Chopsticks and soupspoons are stored on the table in a long stainless box. After you add your customization you stir it by picking up some of the noodles breaking up the wad of them.

After a couple of hours of driving around we finally got to a chicken noodle place. It was on the route home which is good. They were great.

 

rice noodle  ก๋วยเตี๋ยว Ǩwyteī̌yw
boat เรือ Reụ̄x
duck เป็ด Pĕd
fish sauce with pepper น้ำปลาพริก N̂ảplā phrik
fish balls ลูกชิ้นปลา Lūkchîn plā
waterfall น้ำตก N̂ảtk