Impact of Wall Thickness on Pot Volume

I started working on a new design using Shape Cast. I printed out the design proof and it looked good, but the volume seemed off! Is there a bug in the software? Or is it due to the estimated wall thickness of the final ceramic piece? It turns out the be the second and wall thickness can have a huge impact on the volume of your pot!
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[@funkyfungi523]

That was fun working through your problem with you 😁

[@PotterybyKent]

Glad you enjoyed it!

[@Bingabuff]

This is the reminds me of the pizza surface area counter intuitiveness. Going from a small 10 inch to medium 12 inch pizza is only 20% more width, but the surface area jumps from 78.5sq to 113sq, 44% more pizza! (Since area grows exponentially with increase in radius)

[@PotterybyKent]

Exactly and now in 3D!

[@lamardon9723]

I'm confused about loss of volume due to shrinkage. They do get smaller from the just cast size to the bone dry size, right? So you shouldn't be able to use an item to make a mold for a duplicate, right? It shrinks.
Set me straight.

[@PotterybyKent]

Correct, it shrinks. Basically at every stage it will get smaller. From wet clay to bone dry. In the bisque firing, and then finally the glaze firing. For my clay it is 13% shrinkage in total. If you want a "copy" you need to scale up the original by the inverse. So in my case it is scaled up by 1/(1-0.13) = 1.149. As an example, if I want the final top diameter to be 10, the mold would need to be 11.49.

[@lamardon9723]

@@PotterybyKent Thank you very much. Fewer cobwebs in my head now.

[@PotterybyKent]

@@lamardon9723 Great! Let me know if I can answer any other questions.