Hello I am going to use the GlassCast 50 on a 3D picture frame I am going to pour the max amount in one pour (25mm) my question is what paint can I use before I pour the GlassCast 50 on to. I don’t want any funny chemical reaction with the paint as you will be able to see it through the GlassCast. Should I put a varnish onto the paint before I pour the GlassCast 50 and if so is there anything particular I should use? Many thanks.