The chemical make up is why polyester resin dissolves polystyrene foam. Some sheet material has a film protecting the surface, so this could be what protected the foam. It also could have been urethane foam, which is not affected.
You can use polyurethane resins, but there are 2 issues I know of. Working time on many urethane's is short and adhesion. Most urethane's do not like to bond to themselves and they are not very good at bonding to the glass.
You can use polyurethane resins, but there are 2 issues I know of. Working time on many urethane's is short and adhesion. Most urethane's do not like to bond to themselves and they are not very good at bonding to the glass.
