Question on expanding foam

[Jonny]

Picked up foam today again wonder if I'm getting the right one or of one works better the. The other !!

I'm using great stuff. But I've noticed they come in a red black and blue can what can works the best thanks

[froggsong]

The black expands more, so if you need a place to be filled more but don't need to carve it, then use the black. I say a place you don't need to carve because it will have larger voids or "bubbles" inside. The red can is the standard one, and it is good in plces you'll need to carve, because the voids are small. Never use the blue can. Whatever makes it flexible is not good for your herps.

[slim156]

what about the shrinkage. i've never used it but plan to soon. everyone talks about it shrinking. should i leave it unfinished for a while and fill in as necessary.

[HewesHort]

i like to let the great stuff cure for at least two weeks, this allows for any shrinkage to occur and prevents shrinking after you cut into the foam. if you dont understand what i mean, make a glob an allow it to sit over night, then cut it in half. look at it 20 min later and the cut part will be sunken in.

[froggsong]

I personally don't wait that long to carve my GS, but that's because I feel it looks more natural the way it shrinks. If you carve it and sand it and get it just how you want it, once it shrinks it looks less... planned, I guess. If you are worried about the part next to the glass (or whatever) shrinking and possibly pulling away, you can spray the GS in layers, do one full layer (a flat one) against the glass (or whatever), let it cure overnight, then do the top layer and let it cure overnight, then start carving if you want it to shrink. If you don't want it to shrink, then wait a week or two.

[suptrace]

I think i also found some gs that was black, and waterproof... would you not have to silicone it if you were using it for .. say a stream?

[froggsong]

The pond and stone variety (the black, waterproof one (although they are all technically "waterproof" until the skin is broken)) is fine for a stream and won't have to be covered. It does look a little shiny though, I'd think that since it is fish safe it should be ok to rough it with some sandpaper and still have water running through it. In fact, that should grow some good bacteria to help filter the water.

[beckdg]

i would just get some 3m colorquartz black sand and sprinkle it on and press a tiny bit to embed it while the gs cures. then rinse the loose sand out. it'll cost you more though.