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I had painted the 2" foam I had on top of a train board with latex paint from Lowe's. It seems that it didn't soak in and can be peeled off like a thin rubber sheet. I'm wondering if I should thin out this thick paint with water for a first coat to allow it to soak into the foam board better so that it might adhere to the foam better.
Paul
no, the smooth surface of the foam is the issue. Roughen the surface with a SurForm or 50 grit sandpaper to give it some 'tooth'.
I guess that's why I've been having problems in some areas with the latex caulk not sticking consistently between the foam and the roadbed.
Make sure it's not the variety with a very thin plastic vapor barrier also. It's really hard to see but you can dig around in a corner and usually loosen it. That whole sheet of plastic film has to be peeled off or nothing will stick.
Something else is wrong, maybe the thin plastic barrier sheet is still on like Jim said, but I've been painting foam w/latex paint for years & have never had problems. I also glue it together w/Elmers glue, glue sticks or liquid nails. The liquid nails does eat into the foam & I stopped using it for that reason. If you glue it w/Elmers it has to sit for at least a week for it to dry.
If you don't have the really sheer plastic liner, then you should be fine. As for the Liq Nails, make sure you use the formulation for foam.
No plastic sheet on mine (was warned by hobbyists and checked with the foam dealer as well as tried to find it).
Where I've had the greatest problems with roadbed on the styrene foam (using WS roadbed, mind you) is that if the roadbed sheets (for yards) was curled up, then once the caulk has set (a week or more) under weight or pins, when the weight or pins are removed, the roadbed sheet comes up. The other place is at an uneven joint between two sheets of styrene foam (my fault for not leveling it out). Everything else has been ok, as long as I let it set long enough (a week or so).
I had to use Liquid Nails (safe for foam) on two lift-outs because the movement of the lift-out would eventually cause the foam to separate from the plywood.
the foam is waterproof so it absorbs nothing. i was really surprised how long are drying times for elmers, liq nails, and locktite (both foam to foam and general.) the first time i easily lifted section i glued ~24 hours beforehand i went "WTF?!" now i just roughing the surface before i glue stuff and let it sit for more then 24 hours and just work on other area or something else - started on display case and several test areas.
good idea on scrubbing it before painting. was thinking about that to (will be painting soon)
It doesn't take much to rough it up, buffing with a scour pad usually works for me.
It doesn't take much to rough it up, buffing with a scour pad usually works for me.
That sounds like a good idea, I will definately try that. I just found a source for Dow Square Edge Blue Foam and got some, and I don't want to screw it up. Thanks.
Paul
got another "as is" sheet of 2" pinkie for 5$
no, the smooth surface of the foam is the issue. Roughen the surface with a SurForm or 50 grit sandpaper to give it some 'tooth'.
Used your advice on the 50 grit, then painted a piece with Kilz latex. It took most of the day to dry, but it ain't coming up. Stuck like glue. The caulk holding the foam on the board is also down to stay it feels like.
Paul
wierd..........I have been using the blue hi density foam from Lowes and have not had a problem. DOW R3 insulation sheathing BTW. My road beds fine, have not painted it other than to test to see how an ashalt road would look about a year ago. Appears to be the latex paint is set just fine.
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