They are used fabric softener sheets from the clothes dryer.
Quite some time ago, a member of our Canadian Clayamies group shared a tip on using these to remove clay stuck to the pasta machine rollers. (I'm sorry I cannot remember who that was). I since discovered they work amazingly well for cleaning the removable blades from the pasta machines such as the modified machines by Mona or the D.R.E.A.M. machine as well. The clay adheres to the pellon-type material making a quick and easy clean-up.
I also like to reuse the wrappers from the kato clay packages (I buy the large 12.5 oz size) and I will use some pieces of the dryer sheet (after cleaning my pasta machine blades), to wipe the packaging clean so I can use it to store my clay color mixes in afterwards. I find the clay stores much better than using a regular plastic wrap as they will not interact with the clay over time.
You can see how clean the wrapper is after wiping it with the sheet.
I seem to keep making more clay recipes and running out of space to put them so we bought this drawer storage unit to keep it all in.
I have the clay organized by color according to my Clay Color System so it is much easier to find a color I'm looking for.
I always say you can never be too organized! lol!