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This is 8.4L of water (in the bottom of that pail) and a 20kg bag of Polar Ice porcelain casting clay. Amazingly, it is possible to get all that powder into that little bit of water and still have a very fluid slurry for casting. The volume will increase to only 2/3 of this 5-gallon pail. How is this possible? That water has 100 grams of Darvan 7 deflocculant in it, it causes the clay particles to repel each other such that I can make a liquid with only a little more water than is in a throwing clay! All it takes is a few minutes under a good power propeller mixer.
There are 8.8 liters of slip in this 2 imperial gallon bucket. The cone 10 stoneware slurry was propeller mixed in a larger bucket. First I stirred about 3/4 of the projected 44g of Darvan into 4000g of water. Then I dumped in 10,000g of the powder (shaken in a plastic bag) and let it sit to slake as much as possible. Then I used a high-energy propeller mixer, and to finish, trickled in extra Darvan until the rheology was right. The slip itself thus totals 14 kg (31 lb) and has a specific gravity of ~1.75. It has sat overnight and formed a film on the top, but has not settled (indicating that it likely is not over deflocculated). The casting process enables even a hobbyist to make his own custom recipes and tune them over time. Would you like to develop a recipe? We could use a group account at Insight-live.com to work together on it.
Glossary |
Deflocculation
Deflocculation is the magic behind the ceramic casting process, it enables slurries having impossibly low water contents and ware having amazingly low drying shrinkage |
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