I'm making small signs from 3mm thick clear PMMA acrylic sheet. I cut a shape out (such as an oval) with my Speedy 300, I spray one side with acrylic primer, then etch a reversed design into it and back paint it with acrylic colours. I then bond another sheet to the back using clear PVA glue to create a double thickness laminate; this glue is not spread right to the edges. However often within a few hours I see small cracks appearing at the edge of the uppermost piece. Over 24 hours these get bigger.
Does anyone have any idea what might be causing these cracks to appear? Its going to be a real problem for me if I cant solve it.