|Monthly Tech-Tip |
Niko is trained as a product designer so the science and physics of clays and firing require lots of self-learning. She is "salvaging" red burning stoneware materials and hand building these large brick forms for firing between cone 7-8. Drying and firing such shapes without cracking is very demanding. For drying the blocks evenly she made a drying cabinet and put a hot fan to blow in warm air, maintaining an interior temperature of 45C (with high humidity). She puts the blocks on a piece of flat tile and covers them with a cloth to further assist in bringing away the moisture. She is able to fire the pieces on the third day after they have been in the drying tent for 2 days. The drying tent is an idea from the EKWC (European Ceramic Work Centre), these are often used for drying sculptures. Her firing schedule is 80C/hr to 140 with a 1-hour hold, 85C/hr to 650 with a 5-minute hold, 150C/hr to 1130 with a 30-minute hold, 60C/hr to 1230 with a 15-minute hold, 500C/hr to 1130 with a 30-minute hold, 83C/hr to 760.
She is using the DFAC test and SHAB test to systematically characterize each clay. Based on the results she will be able to either blend them or incorporate other materials (e.g. bentonite to add plasticity, feldspar to aid vitrification, kaolin or ball clay to impede vitrification, barium carbonate to precipitate solubles salts, silica to help with glaze fit, etc.). She is using code numbering to organize testing and material location records.
A clay that a potter finds, tests and learns to process and use himself. To reduce the costs of importing materials manufacturers, especially in Asia, often develop processes for clays mined in their locality.