Would it be okay to use watercolors on my acrylic canvas?
It might not work, particularly if the canvas has a plastic coating. If it’s actual fabric canvas, it should work ok. If it’s a canvas-printed board with a coating, try rubbing it (very very gently) with a very fine grade sandpaper before you start. This will help break up the coating and give the paint some adherance, but it may increase bleeding of colour. You may have better success using gouache rather than pan paint (gouache is still watercolour but it’s a bit thicker, and comes in a tube rather than pan or blocks). If it doesn’t work, try using acrylic paint that’s been diluted with acrylic thinners. It flows and blends in a similar way to watercolour paint but it dries quicker. My best advice would be to experiment first and see what works best.
