Waterproofing DTFB

[mmiller1]

I often hear that you guys do some type of coating of dollar tree foam board prior to painting. Especially using water based
paints. The paper tends to de-lam from the foam. Even with regular spray paints (non-water based) I get some wrinkling
even doing several light coats. I have ordered a few of your waterproof foam board and that works great for painting. However, that is not sold at Dollar Tree. I suspect you have an exclusive contract with Adams for that product. Wish it was
available to us scratch builders. You have also mentioned some spray on waterproofers from time to time but I do not
recall what they were. There might be a thread somewhere on your site dealing with this topic, just have not viewed it.
Any help would be appreciated.
Tim

 

[TexMechsRobot]

The most common method is with oil based minwax.

http://forum.flitetest.com/showthread.php?7646-Dollar-Tree-Foam-Board-Waterproofing

http://www.flitetest.com/articles/polyurethane-treatment-of-dollar-store-foam-core

http://www.jonshobbies.com/flite-tests-bloody-wonder-v2.html

 

[ttprigg]

I agree that the best method that I have come across is to use oil based minwax. I use a cheep brush from harbor freight to apply it and then "quickly" wipe it off with a paper towel (hands covered in latex gloves - also harbor freight). You want to get what you can off to reduce added weight. Once the paper is impregnated, I do not think additional material is an advantage. All the "waste" goes out to the garbage--- It can have an odor... I like them white so I generaly do not paint them and they hold up fine (generally long enough to get destroyed with "hard landings" or "hanger rash").
I did get some of the water resistant foam board from FT and it is great! I think that FT is trying to encourage Adams to try to get it into the local DT stores. I'm not sure how we can help with that. I have asked for it at the local level and get the "blank stare" when I mention it...
Good luck!

 

[Hai-Lee]

Living half a world away I have to use what is easily available and I use white glue, (See the thread on stiffening FB). Once dry it can be lightly sanded if required and painted with whatever takes you fancy. The painting does the real water proofing but the glue completely seals the FB and the glue which soaks through the paper improves the bond of the paper to the foam.

Here the local "standard" FB has a real strong paper to foam bond such that it is almost impossible to remove without resorting to heat of similar to break the bond. When white glued the paper is bound together strongly and then the paper peals off cleanly and so I can use the local FB for more of the FT builds which before I could not because I could not cleanly remove the paper from the FB.