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 of >90% Jews. 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, and ongoing problems. For me the lesson was critical.
Ethnocentrism is the concept that from within a cultural viewpoint the actions of the culture seem consistent, meaningful, sensible and from without they can seem otherwise. That our views of things are guided, framed, by our cultural standpoint. Ethnocentrism is strongest 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, etceteraism.
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 seems like it is part of every day, every thought, every moment,, connected, a sinew atttach hair to toenails.
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 percieve it, and how there are different ways to conceptualize the world.
At the same time I was taking an Art History Survey course, An Overview of Far Eastern Art History taught by Professor Walter Spinks. In it, at the beginning of each section, he tried to give us an overview of how a people percieved 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 our concept of 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 to gain perspective. The one idea that I do have is that both frameworks are very abstract.
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. how ceramics melt and sinter, just is not a simple subject.
Perhaps the most general definition is, “A flux is a chemical that promotes melting”. Great! It is a nice concept. 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 it with one part of kaolin clay, one part ground quartz sand, and one part limestone, you can illustrate the complexity.The limestone is traditionally called the “flux”. But if you remove 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. As you remove the limestone, the samme 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”. 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 where the fit is the worst is Boric Acid, B2O3. By formula it should exist in the modifiers. But we add it to lower the temperature, 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.
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.
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”.
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 in my terms, Everything is 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
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.
Controlling Glaze Application Thickness on Porous Bisqueware.
Controlling Glaze Application Thickness on Porous Bisqueware.
Factors controlling the thickness of a glazecoat on bisque.
- Length of time in the glaze
- Density of the glaze suspension. That is how much water is there and how much suspended powder.
- (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.
- 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)
Drying of Clay, thoughts, experience, ideas, dynamics, principles.
Understanding the problems of drying thick work.
It would be easy to assume that drying work that is twice as thick takes twice the time. There are many confounding variables in this, and the simple picture is just not true.
It takes only a little heat to heat water up. It takes 1 calorie of heat to heat 1 gram of water 1 degree celcius. Just to get some comparison, scale in this, a kilowatt hour is 860 thousand calories. Just to avoid confusion, a nutritional calorie is 1000 regular calories.
But to evaporate water, to turn it to steam takes 540 calories for each gram. It takes time, or a big heat differential to transfer all of that heat to the water. As the water evaporates it absorbs heat from its surroundings, cooling them. This is why we sweat to cool ourselves. Evaporation of water absorbs heat.
Clay, especially dry clay is a reasonably good insulator. If you think of that 2 inch thick dinosaur as a bit of water surrounded by insulation, an inch of clay on each side, it is going to take some time for enough heat to penetrate the clay to evaporate the water. Remember, just heating it to boiling is not enough to evaporate it, you have to also get 540 more calories per gram to the water.
Below the boiling point of water at normal air pressure you can only evaporate water until the air surrounding it is saturated, until the relative humidity surrounding the water is 100%. So if you heat clay to say 90˚C or 194˚F and the clay is thick, water inside the clay will only evaporate until the air in the pores is saturated with water vapor. It may not all evaporate until there is time for the water vapor to move through the pores and be exchanged with air from outside the clay.
Explosions happen because the pressure inside the clay exceeds the strength of the clay to contain it. This part of the dynamic creates some compounding factors. As the pressure increases, so does the boiling point of water. This property likely contributes to the wide range of temperatures that we see explosions taking place at. Insulating properties of clay also contribute. the outside of a pot may be above normal boiling, but the inside might be colder from insulation and be at a higher pressure.
Fortunately, not everything makes getting clay dry more difficult. There are a few factors that speed things up. The first is that water wicks through the clay and presents itself, at least in part, at the surface of the clay where heat exchange and drying is easy. In order to understand this well you need to understand three terms, capilarity, surface tension, and viscosity.
Viscosity is the rate at which a liquid will flow. Honey and molasses are much more viscous than water. Acetone has a viscosity that is less than water, but most common liquids have viscosities that are higher. Viscosity of water decreases substantively as temperature increases. This increases its ability to move through clay towards the surface as temperature increases.
Surface tension is a nice term. It describes the tension on the surface of a liquid. When water beads up on a waxed surface the beading is because of surface tension. Without surface tension it would spread out. Surface tension is what holds bubbles intact. In mold making and in bubbly glazes a light spritz of alcohol can cause bubbles to burst. This is because even small amounts of alcohol radically lower the surface tension of the water allowing it to spread out and the bubbles to burst. Surface tension of water also decreases quickly with the rise in temperature. This allows the water to spread across surfaces, say clay particles and present more surface area for drying.
Capilarity, the property of water to up thin tubes or pores decreases slightly with increases in temperatures. The decrease is small enough that in most engineering problems the decrease can be ignored. Due to the increase in speed that this happens due to the decrease in viscosity, in our case it is more ignorable.
The loss of viscosity and surface tension presents us with an opportunity. Clay held at a high temperature maintains a more even wetness because water more easily transfers itself from wet to dry areas. Clay, in general, can be dried more quickly with few problems at high temperatures than at low. The phrase “high heat high humidty drying is used in an old text on brickmaking in the Archie Bray Foundation library and is the place I first encountered the concept. A few years later I needed to dry a thick carved mural quickly and dried most of it at 180˚F in a kiln with the lid propped over night, and some on a table with a fan. The ones on the table all cracked, those in the kiln all did not crack. I was convinced.
In this there are other confounding factors. Almost all electric kilns with the doors open tend to have colder floors. Even with zone control, unless there are floor elements this is likely to be the case. This is because cold air is denser than hot air so it settles pushing the lighter hot air out of the way. The more a kiln leaks, the more trouble there is with cold floors. Drying with the door open is an extreme case of a “leak”.
How wet work is changes the amount of time needed to dry below boiling temps significantly. It conspires with thickness to make thick objects often seem impossible to fire successfully. We have all heard the untruth, “You cannot fire thick work”. Having successfully fired kiln pugs as counterweights, I know this to be an untruth.
While I am still a believer that convection leaves bottoms of kilns colder than tops much of the problem with cold kiln bottoms seems to be the shelf near an uninsulated floor adding to the thermal mass . Work loaded on the shelf with the bottom down adds even more to this. It is not a duplicate of the area near the lid of the kiln. Dispersal of heat at low temperature has to be from convection because radiation is not very effective at the low temperatures. Since none of these factors are very effective with low temperatures or small differences in temperature the added density at the bottom keeps things wet longer. Keeping thick work off the bottom and when possible placing it rim down vastly improves the situation by getting more of the clay higher in the kiln. Most dispersal of heat at low temperatures in kilns is from convection caused by the differences in density caused by air temperature. The colder air heats at the elements near the bottom. This often leaves a cone of colder area near the bottom of electric kilns. So when you are preheating at 180˚F the bottom of the kiln, especially towards the center can be several tens of degrees colder. The colder it is, the less heat is transferred to the water and the slower it evaporates. Most often it seems that explosions happen in the bottoms of kilns that are fired with some, but not enough care.
Optimal conditions are unachievable. We have to fire in real situations. But if you had a piece of clay that was slightly wet, you could heat it above boiling for a short time. The water near the surface would evaporate quickly, but being near the surface would not create any pressure within the clay. The evaporation would prevent the water further inside the clay from heating as it would be absorbing so much heat to evaporate. After that surface water evaporated you would need to lower the temperature. The question is what temperature to lower it to? Optimally this might be above boiling. We only need to stay beneath the pressure that the clay can withstand. Under perfect circumstances we could even do this with leather hard clay. I believe that under normal circumstances we almost never achieve perfect drying and some water is always expelled from the walls of our clay under pressure.
Kiln pyrometers, even type S are imperfect. Even a few degrees around boiling could likely create problems with explosions. Because of this I usually used large margins. I started at 180˚F (82˚C) moved to 190˚F and as I got surer to 200˚F (93˚C). As I got close to retirement I started to use a slow rise time through boiling and shorten the hold. I believe that fine tuning this would result in quicker firings. Because there are differences in our many clay bodies and firings are mixed, “optimal” will vary even beyond considering thickness.
Sometime when I first started teaching at Texas A&M University Corpus Christi, The Island University, The only university in the US on its own island, surrounded by salt water, I decided that I needed a goal for speed of bisque kilns. How many pieces was it acceptable to explode in a semester? If you fire too slow you waste student time, and some electricity. If you fire too fast you either have not allow thick work or you blow stuff up. I decided that blowing up two pieces a semester was enough. Five was way too many. I also decided that this was true regardless of thickness. I started holding back thick work for special firings.
I dried kilns at 195˚F roughly 90˚C. How long the kiln was held depended on the wetness of the work, and how thick it was. I avoided loading thick work near the floor of the kiln. As things got busier and there were more classes, kilns were loaded less reliably. Work on the bottom started to explode more. I added time, a slow rise and then a short hold at 20˚F above boiling to try and get the bottom of the kiln to not explode. This was effective.
I started to think about the slow rise and the ability of clay to contain some pressure. I think that the optimal technique for getting work dry might be a short hold below boiling to get the work hot throughout and then a slow rise past boiling keeping the rise slow enough that the water remaining can boil without creating too much pressure. I think that this would be worthy of study. Knowlege of optimization of brick drying could likely inform what we do and save us time, money, and carbon.
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
Red Curry Mildish
Basic Recipe from https://hot-thai-kitchen.com/red-curry-paste/ Hot Thai Kitchen, a great site for Thai recipes. They also have a nice Facebook page.
I wanted to turn down the heat, and still have it reddish.
Dry Ingredients ground in my coffee grinder (spinning blade type). I clean it out by grinding some dry rice twice.
1t. Salt
1/2 t black pepper
1t lemon zest
4 makrut Thai lime leaves
1 ancho pepper
3 dried chinese store peppers They look like ripe serannos but dry. You can use Thai chillis or anything other than red sweet pepper. If I had ripe serranos or Thai chilis I would use them.
1T Korean pepper powder.
1t Dry cilantro seed
Wet ingredients, if not already chopped I turn them into 1/4 inch size pieces first then process them in a food processor until smooth. This takes opening it and mixing many times.
3T chopped lemongrass. I buy this chopped and frozen.
1t frozen or fesh Galangal (aka Laos or Ka)
1t fermented shrimp paste
1T vegetable oil (aids food processing)
2T Cilantro leaf
Add ground dry ingredients and process until well blended and smooth. Sometime I have to blend by hand.
Nonthaburi นนทบุรี
Khun Doris, then head of the Fulbright was also interested in Pottery. She told of the Pakred and Kohkred potteries. She may have also given us the idea to visit Khun Pisarn Boonpug. I am not sure of this. The potter was also listed in a small book I had managed to purchase on Pottery in Thailand before I left the US.
Koh means “island” and Koh kred is an Island in the Chao Praya river, the river that divides the old Thai capital of Thonburi from the new Thai capital of Krung Thep, City of Angels, known in the west by the little village that the city ate, Bangkok which likely meant village of makok, a fruit. Krung Thep is much more interesting. It could maybe be said to have a mirror in Los Angeles, also City of Angels, but Thep refers to Thai Angles and Krung Thep is only the abbreviated name. The full name, Krungthepmahanakhon Amonrattanakosin Mahintharayutthaya Mahadilokphop Noppharatratchathaniburirom Udomratchaniwetmahasathan Amonphimanawatansathit Sakkathattiyawitsanukamprasit
กรุงเทพมหานคร อมรรัตนโกสินทร์ มหินทรายุธยา มหาดิลกภพ นพรัตนราชธานีบูรีรมย์ อุดมราชนิเวศน์มหาสถาน อมรพิมานอวตารสถิต สักกะทัตติยวิษณุกรรมประสิทธิ์ translates as, City of angels, great city of immortals, magnificent city of the nine gems, seat of the king, city of royal palaces, home of g-ds incarnate, erected by Vishvakarman at Indra’s behest.
Anyhow, Kohkred Island is upstream of there, a nice day trip.
Likely I will get some of the dates wrong, but I visited Koh Kred and Pakred on the eastern bank of the river in 1989. It is not that far from Don Muang airport. On the first occasion we took a boat upstream to a dock near Pakred and walked downstream to the earthenware potteries. We then took a boat across the river to Koh Kred and were met at the ferry by someone who appeared to be a tout. Really he just wanted us to enjoy the Island. He showed us the temple, the murals inside and described some history. The mortars on the island were stout, with very heavy rims and bases. They had more clay in them than any other mortars in Thailand. They were made by the thousands. While the mortars of Dankwian make the worlds most delicious green papaya salad, these mortars held up to the pounding of the pestles. They were durable. I do not know if they are still made.
The fuel in the kilns was palm fronds, the leaf stems. The mortars, fired hot, showed the orange peel texture of salt glazed ware. I asked the locals how much salt they were putting into the kilns. They said “salt doesn’t burn”. I thought
The wheels on the Island and in Pakred were single speed with many wheels run on separate shafts driven by long pulleys. Each wheel had a belt tensioner that acted as a clutch. The technique did not involve centering. The pot was thrown from a large piece of clay on the wheel, but that piece was made out of a pug. The large piece was coil thrown out of the pug. It was an amazing process, there is a little footage of this in Beyond Dankwian, the second hour of my movie on Thai Pottery.
Clay and fuel was brought to the island on boats. We were told that digging clay on the Island was not smart as the Island would sink. It is only a few feet above river level. The Island is small and there are no roads, although there are a few motorcylces that operate on the sidewalks.
The potteries were working hard with people throwing at each kiln site we visited, pots in all stages of production. Back then, the land was cheap, labor was cheap, clay was cheap, and fuel was not too expensive. They were burning palm fronds.
In 1994 I had the honor and good fortune to be invited to be the “Presenter” for a group of potters at the Festival of AMerican Folklife on The Mall in Washington DC.
In 1998 in Ceramics Monthly magazine an article said that the potteries were dying out. Between the visit of the author and the publication in Ceramics Monthly, His late Royal Highness King Bhumipol The Great visited the island and said that it was a beautiful place to visit. I do not have an exact quote. The next weekend the Island was over run with visitors. I visited a month after that and there was hardly room to walk. Not only were there almost no pots, there was no water for sale. You could buy colas and other drinks and knick knacks.
In around 2004 I visited the Island again. It was under stress. There was a lot of pressure for land to be sold for high rises. There has been pressure to build a bridge across the Chao Praya river using the Island. The locals like their quiet life without cars and so far they have been able to protect it.
Check CM for article on Failing pottery.
Check date for visit of HRH King Bhumipol The Great and try and get a direct quote.
Check date of my next visit. Try and find an article on the bridge plan.
Soda or Potash,,, salt does not burn.
offer of a job.
Food Topics
Mae and the Green Snake with the Wood Tale.
Louis, Cashews, Urishol.
Jum, Naem,
UHT Milk
Miang Kam, https://en.wikipedia.org/wiki/Miang_kham
This topic, miang, along with phat pai kaprow, and Choke Chai probably should get attached to Jum.
The VFW in Korat and the Siri,
The Courtyard near Kun Ying Mo with the hot spicy food and the quiet.
HS9DEK Nam Voodoo, and Joy,
Maybe quotes from the journal and insidious intestinal irritants.
Som Tum,
The half life of Kai Yang at bus stations
How to avoid food poisoning
Ghost Gate Market, Talaat Nat today, and The Chicken Lady ,
The old woman and the roasted bananas , paper bags from used paper,
Ease of starting a business, Japan,