They can warp. Choosing the right thickness of 4x8 pvc foam sheet is essential in your signage being able to offer what you need it to do. Just because something is ‘temporary’ or for one-off use only doesn’t mean it shouldn’t be of great quality. The thinner Foamex boards (3mm) can easily warp, not a good look for any brand. Having said that, Foamex board remains...