Hi All

I need a formula for a hobby of mine. I use clay to make things. As it dries- it also shrinks. Depending on which type of clay I use- it can shrink anywhere between 10%-28%.

My question is this (as an example)- assuming I want to wind up with a dried ,finished product with diameter of 25 cms and the clay I'm using shrinks by 12%- What would I need to start off with before I start the drying process? I know most people will multiply 25cms times 12% - then add it to the 25cms for the answer. But 3cms + 25cms= 28cms. 28cms x 12%=3.36cms 28cms minus 3.36cms=24.64cms.

Close - but not close enough.

Anyone have a formula that will work more precisely?

Thanks

Robert