Actually I meant the ground foam, like from Woodland Scenics. I reread it and I guess really didn't say which foam I was refering to. I usually do a base color and texture coat - 99 cent craft paint (Delta) from Walmart stirred into lightweight spackle. After that dries I may paint it a different shade and sprinkle on foam - a basic earth or grass color. Where it goes from there, well, that's a lengthy tutorial... But if the shade of grass/earth/whatever ground foam isn't what I'm looking for I may drybrush a lighter color on top after the glue dries or use a diluted wash of color misted on top.