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tinbucket

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  1. @JDP I would argue that Goldart is not that important. It is just a plastic, buff stoneware clay. It is similar to a high iron ball clay with slightly less plasticity and larger particle size than ball clay. So you could sub ball clay or half ball clay/half kaolin. What clays do you have available to you? https://digitalfire.com/4sight/material/goldart_198.html
  2. You may find this helpful. Although it is for a different application (I think?) the material is basically the same as Keraflex. Someone at Alfred University did some research on "tape casting" which is basically a ceramic matrix spread into a thin sheet using glycerine and PVA (Elmers) glue. A thin, flexible, unfired sheet of clay. Although the set up is relatively simple I think it will require some research and testing - the only advantages I see over Keraflex being availability and cost (although time is money). Good luck! Very curious what you plan on making with it. https://static1.squarespace.com/static/527ac372e4b0d4e47bb0e554/t/527fd23fe4b0f7fd724aba83/1384108607291/tape+casting.pdf The student "cookbooks" in this second link also have some documentation of students' tests with tape casting. I don't remember where, you'll have to scan through and find them. The Alfred Grinding Room website is an excellent resource for other alternative ceramic processes as well. http://www.alfredgrindingroom.com/recipes
  3. One thing to note about colored slips - the more vitrified the slip is the more vibrant the color will be compare to a less vitreous slip with an equal percentage of stain. But the more vitreous your slip is the more problems you may encounter when matching shrinkage etc to your clay body. Green and blue are easy/cheap, I have used up to 20% stain to color a clay body. I would suggest doing a test of 5, 10, 15, and 20% stain additions to weight of dry material then narrowing it down from there. Red encapsulated stain is much more expensive and it might be wiser to use red underglaze instead of red slip or use the red slip sparingly. Below are some tests that some fine people have done adding stains to clay. Keep in mind their base is most likely very white and vitreous, which maximizes the potential of the stain addition. https://www.jakecorboy.com/colored-porcelain https://glazy.org/u/derekau?base_type=400&analysisName=umfAnalysis
  4. I have never used sodium silicate but when I use Darvan I have used 0.2% And 40% water, both of the weight of dry ingredients. That means I multiply the dry ingredients times .002 to get the amount of Darvan and .4 to get the amount of water. So for 10,000g of dry material I use 4000g water and 20g Darvan (add Darvan to water, mix well, then add dry material). This is just starting point and the day after I mix the slip I measure the specific gravity and observe the viscosity of the slip to see if it needs adjustment. It sounds like you slip could possibly be over-deflocculated. Another thing to consider is the way gerstley borate gels, but I'm not sure 2% could have that much impact.
  5. If you notice both examples of running/bleeding you posted are blue, most likely a cobalt (carbonate or oxide) wash rather than an underglaze. If you are after blue, I would use a cobalt wash rather than underglaze. Unless it is very thinly applied, cobalt will have a tendency to run or bleed.
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