Answer:
If there is still moisture on the outermost layer of the clay, then your paint may not properly adhere to the surface. Furthermore, if you use a plastics-based paint ( acrylic paint), you're essentially sealing in the moisture of the clay and it will eventually grow mold from the inside out. You'll need to wait until your piece is completely finished and entirely dried out to start painting. White clay will display paint best. Choose acrylic or tempera paints to color your clay. These kinds of paints are best for painting air dry clay, but you can also use poster paint or even nail polish if you want.
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