Foam Putty works best on expanded polystyrene (EPS). This type of foam is used in the SubTerrain Lightweight Layout System product line.
When used on extruded polystyrene (XPS), the surface of the foam must be sanded with #80-grit sandpaper to give it some tooth, which will allow the Foam Putty to adhere to it. Otherwise, the Foam Putty will not stick to the surface.
Yes, Foam Putty can be painted. The dried surface of Foam Putty is gritty. For a smooth surface, sand dried Putty with a very fine grade sandpaper (220-400 grit) before painting. Apply two coats of paint, sanding lightly between coats.
Here are some drying time guidelines:Very thin layer - 20 minutes An 1/8 " or thicker - 1 to 2 hours or moreThese drying times will vary depending on air humidity and temperature. If it seems slow to dry, place a fan in the room to help circulate the air.
Foam Putty™ has a 2 1/2-year shelf life and cannot be reconstituted. You can determine the manufacture date of a particular container by looking at the code on the lid. The first number denotes the year (8 = 2008) The next three numbers denote the day of the year (085 is the 85th day of the year = March 25) The expiration date for this code is March 25, 2010.