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Magnolia Mud Research

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    : Texas
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    ceramic chemistry

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  1. I have used cardboard, canvas, and/or tarpaper "bats" for large items. see: Vince Pitelka website: https://www.vincepitelka.com/ http://www.vincepitelka.com/wp-content/uploads/2019/02/Throwing-on-Canvas-Bats-as-an-Alternative-to-Rigid-Bats.pdf LT
  2. 1. The 10-12% sugar was added to the 100% of the other ingredients and is not a ratio of sugar to cement; put another way, to 100 grams of the glaze components I added 10-12 grams of sugar. Since it worked, and was a "let's see if this will make an interesting glaze" project and the slurry remained OK, there was no incentive to optimize. I was interested in the fired glaze, not the recipe. The glaze was a beautiful clear over a low iron stoneware; with a pinch of cobalt it make a nice blue. 2. My mixing process was to estimate the amount of water needed based on the true volume of the solids and use a volume ratio of water to solid volume starting point around 0.6. the solid ingredients are added to the water with vigorous mixing in this order: solubles, mix, clays next, mix, light rocks, mix, and heavy rocks last, mix; add a little more water (with vigorous mixing) if the slurry is too thick, and a final vigorous mix. The glaze is ready to use. for the cement glaze, the sugar was added to the water first. Yes, this is NOT what the standard studio textbook teaches ; it is how I was taught to put solids into a slurry (but then, ik ben een chemisch ingenieur). 3. A long range problem with Portland cement as a calcium source for glaze is the storage time of a bag of Portland cement is short, on the order of a few months; once the bag is opened, moisture migrates into the bag and the bag becomes a big lump. LT
  3. I don't remember there being any "rotting" or "stinking" in the container that set in on the shelf for several months after my testing placing a stick of bare copper wire in the container will be a deterrent on "rotting and stinking". LT
  4. The project began from a very early CM magazine article using Portland Cement (PC) [a mixture of tricalcium silicate (3CaO · SiO2), dicalcium silicate (2CaO · SiO2), tricalcium aluminate (3CaO · Al2O3)]. LT
  5. @Piedmont Pottery @Callie Beller Diesel @Min sometime way back I was working with some calcium silicate materials as part of a glaze research project. The problem was how to prevent the calcium silicates forming "concrete" from the glaze slurry sitting still for several days. The answer came from a Professor researching concrete; very small amounts of sugar are often added to the concrete mix when the pour is more than an hour from the mix station to the pour sight; using that data, and a SWAG adjustment from a an hour to "forever", a 10-12% sugar level (of the glaze solids) was arrived; the two gallons of glaze slurry with 10-12% sugar was still just a slurry (settled as soft and easily stirred without needing screening) after a several months setting in the glaze room. LT
  6. mica is possible, but so is a white grog made from high fire kiln wash (alumina+kaolin) added to a red or dark clay body, or grog made from bisqued high fire porcelain. I have used crushed fired dry kiln wash mixed with red clay in a surface slip and get similar contrasting effects for coatings. LT
  7. two articles addressing spray equipment is available on Vince Pitelka's website: https://vincepitelka.com/wp-content/uploads/2019/03/Spray-Equipment-and-Compressors.pdf https://vincepitelka.com/wp-content/uploads/2016/03/Using-the-Gravity-Feed-HVLP-Spraygun.pdf My experience with spraying glaze requires a slurry that is "less viscous" than dipping/pouring glaze slurries, which generally means more water and lower specific gravity. Also remember to always stand upwind of the ware when spraying. LT
  8. Functionality of anything, and especially ceramic art/pottery items, is determined by the user, not the maker; regardless of the maker's intent! A large ceramic vessel designed and manufactured to separate butter from fresh milk is functioning as an umbrella stand. A heavy cylinder of fired clay (closed on one end) is functioning as a paper weight one day; a pencil holder the next day, and recently was functioning the amount of epk going into a batch of glaze, and the when the rain stops will be functioning by holding a window partially open! meanwhile its function is to hold down the table on which it sits so that the table does not float to the roof of the building. I know of a large collection of ceramics items that functions only to fill the space in the corner of a brick building awaiting an opportunity to function in a different way. Yes the use of the word "functional" for ceramic items is ambiguous, but As "The Eagles" says in the opening track of "Hell Freezes Over": "get over it!" LT
  9. a lead article in July 2021 issue of Industrial Heating magazine: How Long Should My Thermocouple Last? https://digitaledition.industrialheating.com/july-2021/how-long-should-my-thermocouple-last/ yeah, the author is focused on commercial applications and the examples are not pottery kilns; however, the discussion of the corrosion of the thermocouple and the protection tube however is generic and does address some important insights not often mentioned in the studio pottery discussions. LT
  10. switch from "hump" molds to "slump" molds; thin use the half-dome steel forms; the clay shrinkage will pull away from the form without cracking. coat the form starch. has worked for me using glass, metal, and "found object" forms. LT
  11. Dianna I have used low fire clear glazes from Amaco (and several other brands) on clay bodies fired to cone 3, to cone 5, and to cone 10 in a gas kiln without problems. The cone 05 maturity for these low fire glazes are slightly above the bisque temperature of these clay bodies; this means that the clay body acts as a sponge for the melt and soaks the glaze. Try it, and see what happens on your clay, the way you apply the glaze, and the way you fire your ware. plan on using cookies until you are determine cookies are not needed. Always remember that thickness of the glaze application is important; thicker often means running. Glaze "fit" may be a bigger problem than running. LT
  12. I’ve used Corn Huskers Lotion in the studio for a long time; it has no oils, don’t smell, does not act as a glaze resist, and is compatible with ceramic materials.
  13. keeping the "shed" cool enough to prevent combustion of the "shed" is important; equality important is to keep the controller of the electric kiln cool enough to properly control the firing; that temperature is likely to be lower than the safety fire protection temperature of the building. LT
  14. I have used watercolors on bisque ware followed by glazes. Treat both as if you were making a watercolor painting. adding some soluble organic material that will act as glue when dried can also help: skimmed milk, sugar, clear water color medium, ... I have used clear acrylic and cobalt blue acrylic paint on both greenware and bisque ware and the acrylic does act as a repellant to water based glaze. Mixing the clear glaze into a clear acrylic would probably work, but why go that route? cobalt acrylic paint does work on both greenware and bisque, but the bonding is poor unless something similar to baking soda added to the "paint' to assist in the low temperature bonding when firing. Keep tinkering with the materials. LT
  15. Vince Pitelka wrote about his homebuilt pugmill: https://vincepitelka.com/wp-content/uploads/2016/03/Building-the-Harry-Davis-Pugmill.pdf The "motor" can be any device, hand cranked, water fall, windmill, etc. I recall reading years ago about using a hand driven sausage grinder for small amounts of clay. a pugmill is just a tough version of a bread/cake mixer. clay mixing has been around a lot longer pugmills. think outside of the standard box and improvise! LT
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