Has anyone used red cap great stuff for background

Ginj

Member
I was building new Cham enclosure and I got to the foam and had it all foamed and cut was looking great and then I put on some silicone and put some coconut fiber and moss on. Came back the next day to look at it and it was shrunk from the sides of the wall like 1-2 in all around. Idk if I did something wrong I have watched a lot of people do it and never seen that so it was a shocker to me any ideas on what to do or how to fix
 
IDK what "red cap great stuff" means. Is that a different brand of urethane foam?

Even under ideal circumstances some shrinkage can occur, but 1-2 inches on all sides does seem extreme.

Urethane foams (UF) of this type require some moisture to aid the reaction and cure properly. If the silicone was applied too soon (before the UF cured properly) it may have prevented necessary moisture from being absorbed from the air. OTOH, with a product like this, errors may have occurred anywhere in the process, from raw materials through application.

A cursory search of great stuff shrinkage suggests one remedy is to fill the gaps & spaces around with more of the same foam. I'd give it full curing time before applying the silicone & fiber.
 
I think @Klyde O'Scope has a good point about curing time. If by ‘red cap’ you mean the Great Stuff for gaps & cracks, I have been using that one with no shrinkage. I let it dry for at least a full 24 hrs, if not longer, before carving and covering. Other possible problems could arise if the can wasn’t shaken well enough, if the temps or humidity weren’t ideal and of course you could have gotten a bad can.
 
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