Slip Recipes For Pit Firing

[negevguy]

i am looking to try some slip casting and would like to know if anyone can suggest a slip recipe for casting that will withstand the thermal shock of pit fired process

[MMB]

Hmm well since I started back in ceramics last year Ive pitfired and saggar fired test pieces of basic vessels that were slip cast, some low fire clay, high fire clay, and natural GA clay. I didnt want anything cherishable going into a fire I knew might not come out. I have lost some pieces and had some survive, thats really the name of the game from what Ive come to understand. The thermal shock aspect really comes from getting to hot to quick. A lot of people who pit fire work up a bed of coals before setting up the pit. They leave their pots around the first fire to help them get warm before the actual process begins. I might be wrong but I do believe that no matter what clay you use there is going to always be a chance of shock to the vessels. Also to slip casting produces weaker vessels than any other preparation of a vessel, I believe its due to a lack of compression of the clay particles. ANother factor as well is if its bisque fired first and also to what cone. If youre pitfiring greenware then you really run the risk of a lot of loss.

 

Hope some of that helps.

[negevguy]

Hmm well since I started back in ceramics last year Ive pitfired and saggar fired test pieces of basic vessels that were slip cast, some low fire clay, high fire clay, and natural GA clay. I didnt want anything cherishable going into a fire I knew might not come out. I have lost some pieces and had some survive, thats really the name of the game from what Ive come to understand. The thermal shock aspect really comes from getting to hot to quick. A lot of people who pit fire work up a bed of coals before setting up the pit. They leave their pots around the first fire to help them get warm before the actual process begins. I might be wrong but I do believe that no matter what clay you use there is going to always be a chance of shock to the vessels. Also to slip casting produces weaker vessels than any other preparation of a vessel, I believe its due to a lack of compression of the clay particles. ANother factor as well is if its bisque fired first and also to what cone. If youre pitfiring greenware then you really run the risk of a lot of loss.

 

Hope some of that helps.

 

 

 

thanks for the input, maybe i will preheat the vessel slowly in a sperate home oven

[meghanmuir]

i am looking to try some slip casting and would like to know if anyone can suggest a slip recipe for casting that will withstand the thermal shock of pit fired process

 

 

Bisqueing the slip cast pieces before pit firing them should give them more stability. I don't slip cast, but I pit fire and bisque my pieces first (bisque cone 018-08 range). I do not preheat and have had no casualties after several firings *knock on wood.