Homemade rock hides nervous about some things!

[PitOnTheProwl]

That stuff is lethal. All flammable chemicals. I'd say get it out of there and don't let any animal near it! At least the stuff I used years ago. Maybe better now, but I'd be leary.

FYI... most all of the backgrounds used in tank displays are spray foam and painted.
As long as the paint has gassed it isnt a worry and it isnt too close to the CHE it wont deform.