I had used Woodland Scenics foam roadbed and thought I'd paint the foam before laying my track. In the area I'm modeling, BNSF uses a mauve ballast, and I wanted to make sure if some of my ballast chips off or exposes the roadbed, it wouldn't look like the dark foam. I used some leftover interior latex from the den. Everything was going well until a week later when it came time to glue down the tracks. When I put the track under the stress of bending around the curves, the paint stuck with the glue and ties and came off the roadbed. Essentially, the paint is the weakest link in the rail-tie-glue-paint-foam-glue-plywood sandwich. A couple of quick wipes with a sanding block removed enough of the paint that it wasn't a problem for the rest of the tracklaying. I still like the idea, but on the next layout, I may try auto primer on the roadbed (if it doesn't eat it away!). [ 13 July 2002, 17:23: Message edited by: ten87 ]
Ed, next time, run a strip of 1" wide masking tape down the center of the roadbed, then go ahead and paint. Remove the tape, glue the track, then ballast.
I don't know if anyone in the US does this, but over here one of the major car stores' own make of car sprays is Acrylic based, designed so you can use it on plastic parts (there's lots of them in modern cars!) I have some of my loco's painted with this stuff!
Thanks guys. I tried some auto primer in a spray can and it didn't attack the foam. Maybe on the next layout...