Heat treat every layer?

Hello! And welcome👏 It's a very good question in fact. None of paint brands mention the need to heat fix every layer. However, as I mentioned in lecture notes for review of PEBEO SETACOLOR paints, there's a problem with their black paint for dark textiles, and so this manufacturer recommends to heat fix each layer of paint. BUT, in real life no one does this because it really isn't practical in small paintings, plus we each time risk to overheat the painting or fabric itself.

So as a conclusion, we do not heat fix each layer of fabric paint, but we do let every layer to get completely dry (simply on air for 1-1,5hrs or you can speed the drying time up by carefully using a hair dryer) prior to applying the next one.