Clay Shrinkage and Absorption Test Kit

There are a few things we as potters need to know such as how much does our clay shrink and what is the absorption rate.

Clay manufacturers list average numbers for each of their clay bodies for these two very important things based on their own firings.

But things work differently in our studios. Working wet or dry will affect the rate of shrinkage, (i.e., wet clay has more water to lose resulting in higher shrinkage). As we all know every kiln fires differently, even the same model from the same manufacturer will fire differently. Now take into consideration your unique firing schedule and even which shelf you fire on. You can see how your results can vary.

Absorption rates are equally important too. Too high an absorption rate will result in your pot weeping when filled with water resulting in pots that should not be washed in a dishwasher or used in a microwave. If you ever mircowaved a mug and found it hot while its contents are still cold it’s because the mug has soaked up water in the dishwasher.

Included in this kit are all the tools you need to test your clay.
• Two STL files to make a test tile
• A PDF ruler to scale to your individual needs
• Two Excel files
- Absorption_Rate.xlsx: calculates absorption
- Size_needed.xlxs: Did you ever need to make something a certain size? I know I have. Let’s say you need a lid for a pot to finish at 7". This file will tell you how big you need to make the lid while the clay is still soft.
• And most important, a set of directions on how to use these tools

PLA
15% infull