The parchment is semi-permeable, so it pulls moisture from below without diluting the paint too much. If you use the roll kind it will curl up into a cylinder. Just wait and it will flatten out. If it doesn’t then your sponge is too dry.

A non-cooking use is in making a wet palette for painting. Place a sheet of parchment paper over a wet sponge or paper towels, and you can use acrylic paint without it drying out. Use something you can cover (like a shallow sandwich container) put it in the fridge, and the paint stays wet for days. Great for projects…