I tried making a hill using styrofoam. The spraycan of paint made it melt. Which fortunatly turned out to look halfway decent so I continued anyway. But now I want to put some protective spray on it to stop the paint from chipping, unfortunatly when trying the usual varnish I use on a new bit of styrofoam it melted that as well. Anyone have any idea what I should use?
Water based acrylics. Water based acrylics. Water based acrylics. ALL rattlecans Melt: Styrofoam®, Foamular®, and the white beaded material people call Styrofoam ( <== because they don’t realize that word is a Dow Chemical trademark ). The only exception is RUSTOLEUM® Brand products. Some of their cans are safe for expanded polystyrene objects. But not all of them! To seal: use (brush on) acrylic matte medium. Use gloss if a wet look is wanted.
As @Crowsfoot mentioned, the cheapest solution is watered down PVA glue. If you have any wallpaper/floor glue lying around, you can also use that watered down.