"I purchased these cards to create watercolour swatches of my palette and mixed colours. They did not disappoint. Paint goes on smoothly and no buckling of the card. If you work them a bit they do pill slightly but they can handle a few swipes back and forth. Once left to dry the cards have curled very slightly, but I think pressing them under a heavy book would correct that (it doesn't bother me for my purpose). Very happy with my purchase."
ATC Blank Artist Trading Cards,300gsm Premium Cards,89mm x 64mm, Pack of 100