sealing before painting cardstock?

I am printing out kits in several scales in 200lb card stock. I would like to seal the cardstock so that it does not fray or have the layers come apart, before I cut them out. Or afterwards. But the sealer must allow the customer to be able to paint the cardstock with whatever medium they wish - whether paint - markers - chalk - etc. Is there any recommended sealer to do that with?



Its kinda a reverse thing from other sealer questions. seal it before painting as opposed to afterwards.... idea?



Karen