View Full Version : How to NOT use Pink rigid insualation

11-21-2012, 05:07 PM
So, I have a project that calls for me to shape some 2" thick rigid insulation in to various shapes. The plan was to prime them well, then paint with outdoor latex paint. In addition, on some items, I was planning on using the foam for 'structure' followed by applying layers of fiberglass mesh and fiberglass on the surface to create a more rigid structure.

Here is what I learned:

1) When you apply liquid fiberglass on top of foam, apparently the don't like each other and the fiberglass literally melts/eats your foam
2) In addition when you try to use Spray Primer on the foam, it also does no get along well. It too either melts/eats the fiberglass.

Kilzn primer in a can, applied with a brush appears to work fine.

As GI Joe says: "And now you know!... And Knowing is half the battle"

11-21-2012, 05:20 PM
Coat the foam in a couple of coats of "white glue" (you can water the glue down a tiny bit). With about three coats, you can then use spray primer (and I would think your fiberglass resin)
This technique also works on closed cell foam (rubbers).

11-21-2012, 05:54 PM
I recently glued this stuff to the concrete walls when I finished my basement before studs/sheetrock. I only used the specially formulated liquid nails foam glue they sell. I am sure you can use other things but with me needing 50 sheets and the stuff being so darn expensive, I was not taking any chances!!

Greg in Canby
11-21-2012, 07:32 PM
Prime with any water based latex paint. If covered 100% then you can paint with just about anything. Not sure how it would take resin, never tried it. Also, I glue it with gorilla glue, liquid nails took too long to set.

2 cents.


11-21-2012, 08:10 PM
greg, thanks. The regular water based Kilzn worked fine. Just not the spray version

11-21-2012, 08:51 PM
I learned the hard way too. Quite a gooey mess. If you use epoxy resin instead of polyester resin it won't melt the foam.
You can get epoxy resin from surfboard supply shops or marine shops.

I've never heard of the white glue thing. I'll have to give that a try.

11-21-2012, 09:27 PM
Other interesting thing I found about this product. If you sand it with the grain on a belt sander, it sort of melts and re-hardens like a thin glaze. I was able to peel it of but I thought it was an interesting property. If I sanded the other direction it was fine.

11-21-2012, 10:46 PM
That reminds me of the time I tried to pour a little paint thinner in a styrofoam coffee cup. Yup, it disolved the cup's bottom and went everywhere.