My partner and I recently started renting a pottery wheel from a local pottery school so we can practice at home. We bought one 20 lb bag of clay with the intent to recycle it.
We wash our hands and our tools in a bucket and then dump that water into a larger bucket. This larger bucket also holds all our scrapped work, trimmings, etc. The clay will sink to the bottom and we can decant the water on top, allowing us to keep adding to it.
After a while, my partner scooped up the clay and placed it on pillowcases on a sheet pan and we let it dry for a week or so, flipping it one time.
Many people make plaster bats for this, but it's too cold to do work that dusty right now.
After it became dry enough, we tag teamed slam wedging it. We formed blocks and then sliced the blocks, alternating the newly sliced slabs to build new blocks...and then slam wedged those. This is to incorporate all the clay together and get as homogenous of a mix as possible.
I'm going to spend some time throwing from the recycled clay today!
Interestingly some contamination can improve the properties allegedly. Many potters insist that mouldy clay, while somewhat disgusting to work with, has better plasticity!
I've been meaning to test the air bubbles claim, it confuses me because even stonewear is not air tight and I have difficult imagining that it would cause cracking on its own. I tried to find papers examining it and couldn't. Structural weakness? yeah sure but I feel like uneven heating or uneven particle distribution would be the significant factors for failure on firing. Unfortunately I lack the ability to heat and cool in a repeatable way with a fire in the yard :(