missholly Posted May 31, 2014 Report Share Posted May 31, 2014 when my slip molds are drying, the clay cracks all the way through the ware. i tried lowering the water content and adding sodium silicate, but it didnt help. help? Link to comment Share on other sites More sharing options...
Mark C. Posted May 31, 2014 Report Share Posted May 31, 2014 More info is needed? Are this molds flipped and drained and the form is cracking before opening the mold ? Are these forms cast solid? Have you made this slip or is it store bought slip? These days one uses Davon 7 instaed of sodium silcate and you use a slip hydrometer and a viscosity cup to measure slip water content before casting-was this done? Mark Link to comment Share on other sites More sharing options...
missholly Posted May 31, 2014 Author Report Share Posted May 31, 2014 the molds are flipped and drained, and almost immediately, cracks all the way through form. i made the slip. ive used this slip before with no problems. ive tried adding water, taking all the water out. i havent used the viscosity cup or hydrometer. Link to comment Share on other sites More sharing options...
neilestrick Posted May 31, 2014 Report Share Posted May 31, 2014 Was your original slip deflocculated? If not, then you're going to get cracking. The shrinkage rate will be much to high. Adding sodium silicate later is too inaccurate. Start with a fresh batch of deflocculated casting slip. Here's a recipe: Slip Mixing Instructions.pdf Slip Mixing Instructions.pdf Link to comment Share on other sites More sharing options...
missholly Posted June 1, 2014 Author Report Share Posted June 1, 2014 its reclaimed. Link to comment Share on other sites More sharing options...
ashraf elhamy Posted June 7, 2014 Report Share Posted June 7, 2014 Maybe cause of one of 2 reasons: 1 the drying cycle is fast rate causing this cracks 2 or the drying process is not homogeneous Link to comment Share on other sites More sharing options...
Babs Posted June 7, 2014 Report Share Posted June 7, 2014 Reclaimed? Ie dried out casting slip and rewet? This would nullify the deflocculant of the slip, as Neil said you'd have to defloc the reclaimed slip. Link to comment Share on other sites More sharing options...
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