Dominique MP Posted June 5, 2021 Report Share Posted June 5, 2021 For years, I made teapots and other functional pieces from combining slip cast elements. I recently wanted to upgrade and began using Mayco Stoneware slip. While I like cone 5-6 glazes better, as well as the durability that stoneware gives to my work, I am finding that many of my pieces are undergoing warping during the glaze firing. I have never used porcelain slip, but love the look of it- I've been intimidated to work with it because I've heard it's difficult. Before I invest too much more, what can you tell me about the workability of porcelain for my needs? Thanks! Link to comment Share on other sites More sharing options...
Jeff Longtin Posted June 7, 2021 Report Share Posted June 7, 2021 I've been using cone 5-6 Porcelain slip for years and I really like it. I found 5-6 stoneware slip to take forever to set up. You seem to differentiate between 5-6 and porcelain, are you thinking about cone 10 porcelain slip? Years ago I mixed up a batch of the standard 25/4 recipe (25 kaolin, 25 Ball clay, 25 feldspar, 25 flint) and found the body to be very unfriendly to casting. You may have better luck though? Link to comment Share on other sites More sharing options...
Dominique MP Posted June 7, 2021 Author Report Share Posted June 7, 2021 Thanks for your response. If I did switch, I would likely stick with cone 5-6. Do you have any experience with altering the porcelain forms? I keep hearing that porcelain has a memory, and I wonder if this would prohibit me from making the forms that I am? Or do I instead make a mold from pieces that I’ve constructed out of some other clay? Link to comment Share on other sites More sharing options...
neilestrick Posted June 7, 2021 Report Share Posted June 7, 2021 Cone 6 porcelain is beautiful stuff, but it won't cast or handbuild or throw as nicely or easily as stoneware. A true porcelain that doesn't have any ball clay definitely won't cast as well, so I would find a recipe that has some ball clay. It'll work better in the mold and have better dry strength. All clay has a memory, but I would think that would not be an issue when casting because you're not compressing and aligning clay particles like you do when throwing and handlbuilding. Porcelain is more likely to warp than stoneware because it get so close to its melting point and softens up at the high end of the firing. You may be able to compensate for that to a good degree by making pieces thicker, though. I'd pick up a gallon of cone 6 porcelain slip and give it a try. Link to comment Share on other sites More sharing options...
Jeff Longtin Posted June 8, 2021 Report Share Posted June 8, 2021 On 6/7/2021 at 5:46 AM, Dominique MP said: Do you have any experience with altering the porcelain forms? Yes, I distort porcelain castings all the time. (And then I remold them and create new forms.) I find cone 6 porcelain to accommodate this process quite nicely. Remember there are two types of cone 6 porcelain out there: one using Grolleg kaolin, nep sye and flint, and another using EPK and #6 Tile and maybe some ball clay?, and they have different workability qualities. The grolleg porcelain is a little more white but it is a little more short. (less plastic) While the EPK variety is a little more cream colored but a little more plastic. How well a clay serves your purposes really depends upon what you intend to do and your skill level. All clays have challenges. How you adapt to these challenges is really the key. Link to comment Share on other sites More sharing options...
Dominique MP Posted June 8, 2021 Author Report Share Posted June 8, 2021 That gives me hope! I guess the best thing is to try. Thanks so much. Link to comment Share on other sites More sharing options...
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