I have a dilemma here with product compatability. I feel that the best way to solve this problem is to put it out there for the experts, or the experienced ceramic gurus...
Background of issue:
Products we are using are: Laguna Clay (White EM330), Mayco Stroke & Coat Wonderglaze for Bisque and Duncan Pure Brilliance Glaze (Clear).
My students utilize the Laguna Clay to create their own personal masterpieces which then are allowed to dry to Bone Dry state (min 72 hrs). The pieces then are fired to cone 06 and then allowed to cool before removing from kiln (min 24 hrs). Students return and utilize the Mayco Paint to decorate their pieces. We then apply two coats of the Duncan glaze and allow 24 hrs of drying time. The pieces then are final fired to cone 04 and then allowed to cool before removing from kiln (min 24 hrs). Upon removing pieces from the final firing we allow them to acclimate in the garage space before bringing them into the air conditioned studio. We are noticing crazing the moment they come out of the kiln and only increasing as the pieces cool. The photos below reflect what is occurring (click on photos for enlargement).
At the point, we've researched and the best method of solving this problem is that we need to either modify the clay or the glaze. This modification method that we have read about in numerous articles and blogs requires adding or deleting components of either product (ie. silica, aluminum...). We are uncomfortable modifying premanufactured products (clay/glaze) that have worked well on the bisque products. So in other words, the clay fires fine, the glaze works perfect on the bisque (no crazing) and the paint looks fantastic on all products. What do you recommend at this point?
Options that we are going to test:
1. Fire glazed clay pieces today at cone 06 in lieu of cone 04.
2. Purchase Mayco glaze (clear) and utilize over Mayco paints.
3. Switch clay to either a different brand, different color, or a different firing temperature (high vs low).
Help me out here. What do all you atists recommend?
My friends and I use walkers clay and different brands of underglazes and are still experiencing crazing using the new green glaze
ReplyDeleteInreasing your bisque temp to cone 04 and decreasing your glaze temp to 05 or 06 should help with glaze git issues. Most low fire glazes are designed to fit 04 bisque and are fired a cone or two lower than the bisque temp.
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