MAKING A SPRAY FOAM BACKGROUND
Well now we're at the step of making a foam background that can have wood stuck into it and plants growing on it.
1) Lay your terrarium on it's back and start spraying the Great Stuff spray foam insulation on the back panel, when you've covered the back lay some driftwood in the foam and allow it to harden. You can do the left and right sides too if you want but I wanted 4 viewing angles on this one (F, LS, RS, Top).
2) After a couple hours the foam will be hard enough to stand the vivarium upright and clean the glass if you've gotten any foam where you didn't want it. Use a razor blade flat against the glass to scrape it right off. If you really hate what you've done wait until it's totally cured (hard) then scrape it off the back wall with a painters putty knife and try again. remember if you want to make ledges or rocks with the spray foam you have to let the first layer cure first overnight then add the next layer of foam depth. I just did one layer. This here is a whole can of Great Stuff.
3) white foam isn't very exciting so we'll use a paintbrush to smear black aquarium silicone in all the hills and valleys in the foam.
3) This is the same mix I used for coating the DIY foam "vine", LFS, Coir and Orchid Bark. Pile it on thick and press it down into the silicone and leave it a few hours. It's best to work in sections like this.
4) Black silicone comes in huge caulking tubes so you'll need a caulking gun.
5) I didn't wanna work in small sections so I slathered it all out and busted my hump to get it spread before the silicone skinned over, don't do this, it works out fine but it's much more work!
6) Here is the foam all mounded up with the surface mix, the leftovers will be used as the "soil" for this tank.
7) After you let it dry and stand it up the excess will fall off and need to be cleaned up. Here you see my "waters edge" false bottom already installed and the main piece of driftwood which was too short by 6" or so. So I glued a hunk of foam on the end of it and covered it in silicone and grow mix, once the grow mix has moss on it the "trunk" should look pretty sweet and nobody will know what I've done.