Reptile & Amphibian Forums

i used great stuff as a background in my red eyed tree frog enclosure. i layed the tank down and filled in the back with the foam amd stuck driftwood through it much like the blackjungle.com terrarium. then i covered it in silicone and put spangum moss on next. well it looked great. there is about 2 inches of water in the bottom and a trickle waterfall. well about a week later the great stuff foam started to shrink away from the sides and the water. it shrunk out of the water completely. i thought this stuff was supposed to be waterproof. also i know there is another foam in a can product that is made with different base ingredients. can anyone help or know why this happened???? thank you

I'm not sure what brand you used, but when i was making a similiar cage the first foam i tried ended up spongey even when completely dry. After this i went out and bought a different kind that is suposed to be sandable/paintable I do not run water over it but it is in a humid cage and seems to be holding up fine.
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I experienced the same thing and I used it in a background with no water contact. What I found after destroying a few practice backgrounds is that it really needs to cure fully. This means that when applying GS, you need to layer it and let each layer cure completely.

What I do is spray a thin coat, about 1- 2" and let it dry. It also helps to put it in the sun to speed up the process. Then apply more layers the same depth and let them cure. Apply as many coats as desired using the same technique. It takes longer but you will get the results that you want.

Rob

>>i used great stuff as a background in my red eyed tree frog enclosure. i layed the tank down and filled in the back with the foam amd stuck driftwood through it much like the blackjungle.com terrarium. then i covered it in silicone and put spangum moss on next. well it looked great. there is about 2 inches of water in the bottom and a trickle waterfall. well about a week later the great stuff foam started to shrink away from the sides and the water. it shrunk out of the water completely. i thought this stuff was supposed to be waterproof. also i know there is another foam in a can product that is made with different base ingredients. can anyone help or know why this happened???? thank you

I made my iguana's waterfall out of the same stuff and it worked great, but I had a similar thing happen when I used it for something else, so here's my guess... Water doesn't hurt the foam. In fact, the foam cures by making use of the humidity in the air. One of the best ways I found to cure large hunks of semi-dry foam is to poke deep holes and actually squirt water in. My guess is that the shrinkage occured because of a reaction caused by the silicone (ever see how PVC glue eats through styrofoam?). I had this happen once when I used "Great Stuff" to fill in the empty void in a steering wheel, then tried to glue the cover back on with silicone. It slowly shrunk just like you described. Hope this helps! Good luck!