Sixteen kinds of clay. No mugs have cracked in drying. Why?

Friday 15th January 2016

The key is avoidance of methods that result in one part of the piece being stiffer at any stage of drying (not vinegar in the water, compressing the bottoms, etc.). Throw mugs with walls of even thickness. Put them on a insight-live.com/glossary/7">plaster bat (it dewaters the base). Make the handles a while after you have made the mugs (they stiffen quicker). Apply them as soon as the rims are stiff enough to maintain shape (in my climate, two hours). Use a join method that enables application of lots of pressure (better than scoring). Use only enough slip (of thick cream consistency) to make the join (no excessive squirting out at the perimeter). Pack all the mugs closely on bats, rims up, cover with flowing cloth (e.g. arnel). Put them inside big bags or wrap plastic around and tuck it under. Trim the bases the next day (to the same thickness as the walls). Place rims down (with handles at the center) on smooth batts (not plaster) and cover them with large fabrics that can wrap under leaving no holes exposed to the outside air (in our dry climate two days dries them).

Pages that reference this post in the Digitalfire Reference Library:

Drying Ceramics Without Cracks, Strange drying crack on a porcelain mug, Drying Crack, Handles

This post is one of thousands found in the Digitalfire Reference Database. Most are part of a timeline maintained by Tony Hansen. You can search that timeline on the home page of digitalfire.com.