Pottery Shrinkage Tool

Size it right. Account for the natural reduction in size as your clay dries and undergoes the chemical transformation of firing.

Standard stoneware is typically 10-14%.
Estimated Fired Size
17.6

Total reduction of 2.4 units.

Shrinkage Type
Total Linear
Remaining
88%

Understanding Clay Physics

I genuinely believe that clay is a living material until it hits the final temperature in the kiln. Shrinkage occurs in two main phases: **Drying**, as the water between the clay particles evaporates, and **Firing**, as the chemical water is driven out and the particles fuse together (vitrification).

Finding Your Rate: To find the exact shrinkage of your clay body, make a test tile. Mark a 10cm line in the wet clay. Measure it after it is bone-dry and again after it has been fired to your target cone. The difference will give you your precise shrinkage percentage.

Pottery Design Tips:

  • Lids: When making a jar and lid separately, use the same clay and ensure they are fired together to keep their shrinkage consistent.
  • Throwing Big: If you need a finished 10-inch plate, you may need to throw it at 11.5 inches to account for a 13% shrinkage rate.
  • Joinery: Always join clay pieces (handles, attachments) when they are at the same moisture level to prevent them from shrinking away from each other and cracking.