# Great stuff foam BG falling forward



## Scags (Oct 9, 2011)

Long title I know.
So I recently started a build- Exo Terra 36”h x 24”l x 18”w. It’s a beast. The biggest vivarium I have done. 
I used 3 cans of great stuff-with some wood to create a background. Waited a couple days. Everything looked great. Carved it up, and finished it off with a coating of silicone and coco, fir bark, sphagnum mix.

I then waited another 24 hours. All looked well. Foam felt secure. Finished the substrate area and began planting. 

Fast forward a week. The foam has begun to droop and fall forward.

The question is- what are my options? 
the tank is humid and wet, and full planted. Can I put silicone On the glass behind the foam and clamp it- let it set for a couple days? Leave the top off and stop misting. Or will it still be too humid for the silicone to cure? Or can I try something like gorilla glue white, or maybe a wet curing sealant- then clamp the foam and let it set?

Just not sure what to do. This is my first foam background. I read that some people recommend using silicone first then foam- but none of the video tutorials I watched did that. They just seem to spray the foam in.

Any advice would be greatly appreciated!


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## Lunchmeat (Nov 10, 2020)

Any pics?


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## Scags (Oct 9, 2011)

Lunchmeat said:


> Any pics?


Yeah, not the greatest pics, but here you go. Might be hard to tell. I went really thick with the great stuff- perhaps too thick- which maybe that was my problem.


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## Scags (Oct 9, 2011)

Anyone?


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## jgragg (Nov 23, 2009)

Alright, I'll bite. Here's the deal. You fucked it up, solid.



> I read that some people recommend using silicone first then foam- but none of the video tutorials I watched did that. They just seem to spray the foam in.


See the problem yet? It's just so easy to lie with television. You gotta put the R in RTFM. Read it. Not watch it.



> I went really thick with the great stuff- perhaps too thick- which maybe that was my problem.


Besides trying (and failing) to get something that doesn't stick well to glass, to stick to the glass - yeah, going too thick too fast is another flavor of fucking up with expanding PU foam. If you'd RTFM'd you'd know to layer it, not try to do it all in one go. Put too much on at once and it doesn't cure fast or completely in the middle. So now you've got a compound fuck-up.



> Can I put silicone On the glass behind the foam and clamp it- let it set for a couple days? Leave the top off and stop misting. Or will it still be too humid for the silicone to cure? Or can I try something like gorilla glue white, or maybe a wet curing sealant- then clamp the foam and let it set?


Alright slow down. 
What is the very best thing to stick to glass? Silicone. You need silicone between the glass and the foam.

Personally, i doubt the foam is done pulling away from the glass. Over months, as that background fills in with plant growth and gets heavier and heavier, the stress will accumulate. If you're lucky you'll just get a slow pull-away. More likely, some morning you'll walk in and see a wreck.

So I think the question before you is, can you get enough silicone behind the foam to keep it from collapsing? One way is 100% positive - pull that bitch out, and stick it back in. Just acknowledge your rookie fuck-up, let it hurt, and never *ever* do it again. The other way is try to get the silicone behind the foam while it's still in the tank. Maybe you can manage that. I doubt it. But maybe.

One last thing - humidity helps expanding PU foam AND "normal" silicone cure. By all means, do NOT try to reduce the humidity around curing foam or silicone. If anything, water can be helpful to accelerate and completet the cure. Just use a spray bottle set to super-fine, and hit it lightly but often.

In closing - there's a wealth of info on DB. There is ZERO reason - other than failure in due diligence - to have suffered what you are suffering. If you've got the time to come on here and ask questions, you've got the time to do some research. I recommend that before you do anything else in that viv, you do the research here that you should have done before. Maybe that'll learn ya.

Good luck, chin up.


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## Scags (Oct 9, 2011)

jgragg said:


> Alright, I'll bite. Here's the deal. You fucked it up, solid.
> 
> 
> 
> ...


Great response and I appreciate the honesty. 

I certainly fucked up. I did do some reading prior to jumping into this- but not as much as I should have. That’s for sure. Otherwise I wouldn’t have this issue. I should have done more reading

I did do some research. I’ve been doing vivariums for many years- however, never have I done a foam background. I had always done Tree fern panels or kitty litter/clay. Those were smaller Vivs though, and this one was just too tall and big for that work well. 

The plants are not rooted yet, so I may just say “hey, time to rip out the background and start over”. You are also correct about the foam not being done shrinking. The bottom has shrunk up as well, but not as noticeable as the top. So I’m sure there is more fun times ahead with this BG.


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## Chris S (Apr 12, 2016)

If I were you, at this point in time, I would redo it. I've salvaged some smaller builds that start to peel away by applying silicone, but nowhere near what you would need for yours.

Once you get frogs in there, fixing it becomes a lot more troublesome. You are actually lucky to see it peel off a bit at this point in time, instead of later. Save yourself some future headache and redo now.


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## Scags (Oct 9, 2011)

Chris S said:


> If I were you, at this point in time, I would redo it. I've salvaged some smaller builds that start to peel away by applying silicone, but nowhere near what you would need for yours.
> 
> Once you get frogs in there, fixing it becomes a lot more troublesome. You are actually lucky to see it peel off a bit at this point in time, instead of later. Save yourself some future headache and redo now.


thanks, yeah I think I might tear it out. Still haven’t fully decided yet. I have so many plants in there, not to mention the wood I paid for that will be ruined because it’s covered in foam. It’s a hard decision.

You know, I went and did some research here on Dendroboard and elsewhere. Seems there is no consistent answers on how to do this. Some people still suffer from peel away even when they have a silicone layer behind it. But many people don’t even do a silicone layer behind it. Others use plastic egg crate- then the foam adheres to that, and gives some structure to it.

Thanks for the responses though.


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## kennyb123 (Oct 20, 2019)

Scags said:


> You know, I went and did some research here on Dendroboard and elsewhere. Seems there is no consistent answers on how to do this. Some people still suffer from peel away even when they have a silicone layer behind it. But many people don’t even do a silicone layer behind it. Others use plastic egg crate- then the foam adheres to that, and gives some structure to it.


Yeah I couldn't agree with this statement more. I had a similar issue but fortunately it was in a corner and it was fixable by using great stuff to plug the void (I don't think it would work in your situation).

But I was told "if I had done research this wouldn't have happened, there's so much information on DB." The latter half of that statement is true, but it being a forum there is a lot of conflicting information. I saw 3 methods commonly discussed for foam backgrounds: clean the glass with alcohol and then use great stuff, put a layer of silicone down and then use great stuff, and lastly silicone eggcrate to the background and then use great stuff on the egg crate (this is what was recommended to me on my post). And while I agree that the last method is probably the best, the idea that if you researched background construction on this forum, that this is the clear conclusion that you would come to, is false. 

Good luck!


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## Scags (Oct 9, 2011)

kennyb123 said:


> Yeah I couldn't agree with this statement more. I had a similar issue but fortunately it was in a corner and it was fixable by using great stuff to plug the void (I don't think it would work in your situation).
> 
> But I was told "if I had done research this wouldn't have happened, there's so much information on DB." The latter half of that statement is true, but it being a forum there is a lot of conflicting information. I saw 3 methods commonly discussed for foam backgrounds: clean the glass with alcohol and then use great stuff, put a layer of silicone down and then use great stuff, and lastly silicone eggcrate to the background and then use great stuff on the egg crate (this is what was recommended to me on my post). And while I agree that the last method is probably the best, the idea that if you researched background construction on this forum, that this is the clear conclusion that you would come to, is false.
> 
> Good luck!


I’m glad someone else understands!
Yes, the forums are overflowing with a wealth of information- albeit very conflicting information much of the time.
I did my research, watched a handful of very skilled folks doing the backgrounds. I just applied that knowledge to my build. And boom! I suffer from the peel away. 
I think it’s partly because the tank is so big, and I’m getting more shrinkage than I expected.

still debating on what I’m going to do.

I appreciate the response and kind words though!


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## Chris S (Apr 12, 2016)

Scags said:


> thanks, yeah I think I might tear it out. Still haven’t fully decided yet. I have so many plants in there, not to mention the wood I paid for that will be ruined because it’s covered in foam. It’s a hard decision.


I wouldn't worry about the wood...just reuse it. Use some drylock or something and paint it up a bit if it stands out. You can also use sandpaper to remove excess great stuff if needed.

Best advice, in addition to the things you already mentioned (egg crate, silicone, etc.) is, especially for big tanks: Be patient and do it in smaller sections. This way it isn't one big piece that pulls itself away, but smaller areas. Even if you do them an hour or so apart, they seem to be more solid that way. When you are finished, and have carved it down a bit, silicone the edges down as well - seems to help that initial "peel".

There is a lot of trial and error with this stuff, good luck!


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## Scags (Oct 9, 2011)

Thanks! Doing it in smaller sections is a smart idea. I will definitely take my time- I’m just going to toss all my plants int a plastic bin with a light while I fix this tank!


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## jgragg (Nov 23, 2009)

I'm glad you're taking this feedback well. It bodes well for a positive outcome in the viv.



> I wouldn't worry about the wood...just reuse it. Use some drylock or something and paint it up a bit if it stands out. You can also use sandpaper to remove excess great stuff if needed.


Exactly - the wood isn't garbage, but it is part of the fuck-up. Different species of wood have different degrees of "oiliness" and different adhesion resistance / compliance. With some woods you'll be surprised - perhaps aghast - at how cleanly and easily PU foam pulls away from the wood. Might just leave a little discolored stain where it sat (or maybe it's a clean spot? ha ha). Other woods - hello elbow grease! 

Regardless, besides some coarse sandpaper (60 or 80 grit - which you may not even need) - if you don't already own one, get yourself a narrow scraper - an inch or 1.5" wide. Go to the paint section at Home Depot or whatever - that's where they keep scrapers. Or, go to the drywall section and get a narrow putty knife. Steel, not plastic (the plastic ones can be good for artsy sculpting of epoxy or grout, but aren't hard enough for serious scraping - only steel is). They come in quite a few different widths and thicknesses / stiffnesses. Since I do a lot of home repair & remodeling, I have about 8 or 10, in different widths & stiffnesses. For viv crafting, the narrower and more flexible ones are the go-to ones. My experience, anyways. I'm not talking about the razor type ("glass scraper"), but the ones that look kind of like a spatula ("light-duty paint scraper"). There's also a heavy-duty paint scraper that you don't want - those also have a replaceable blade, like the razor kind.

The light-duty paint scraper (or drywall putty knife, whichever) will come in handy on the wood, and also on the glass.



> But I was told "if I had done research this wouldn't have happened, there's so much information on DB." The latter half of that statement is true, but it being a forum there is a lot of conflicting information. I saw 3 methods commonly discussed for foam backgrounds: clean the glass with alcohol and then use great stuff, put a layer of silicone down and then use great stuff, and lastly silicone eggcrate to the background and then use great stuff on the egg crate (this is what was recommended to me on my post). And while I agree that the last method is probably the best, the idea that if you researched background construction on this forum, that this is the clear conclusion that you would come to, is false.


I said it, so I'll own it. I'll even say it again, but perhaps with more nuance. NOBODY would have said "you don't need to clean the glass first". NOBODY would have said "it's OK to just lay down a shit-ton of GS on there all at once - it won't be a problem". And, a clear reading and synthesis of all the info on the board would have led to this sequence as a *Best Practice for In-Tank Foam Background Construction*:

1) clean the glass to remove any oils or other contaminants
2) apply silicone, either alone or to adhere egg crate
3) foam on that, in stages or "lifts"

I'll say a little more below. Don't assume you need to build it in-tank. I find it physically uncomfortable and artistically inferior to do it like that, actually.

I've got a pair of 36x18x36 Exos with extensive areas of foam (plus some cork mosaic) on back and sides, as well as nine other vivs (some glass, some plywood) with some foam in them. _Not one_ has eggcrate, ANYWHERE in it. But all the glass ones feature a thin smear of silicone between any foam and glass.



> Best advice, in addition to the things you already mentioned (egg crate, silicone, etc.) is, especially for big tanks: Be patient and do it in smaller sections. This way it isn't one big piece that pulls itself away, but smaller areas.


Also excellent advice. I'll take it a step further. Nobody said you have to build the foam background inside the tank. You could also build it (or its constituent parts) on a bench or tabletop. You also don't have to use expanding foam - ever considered foam board? Or, as I have done many times, a foam-board base & major build-ups, with expanding foam just to fill cracks?

Good luck. Now go rip off that band-aid.


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## Scags (Oct 9, 2011)

jgragg said:


> I'm glad you're taking this feedback well. It bodes well for a positive outcome in the viv.
> 
> 
> 
> ...


great response! And thank you. You are right about the fact that nobody on here said to spray way too much GS. Which is what I did. I actually did it after watching a SerpaDesign video- where he did extra thick, and said it might lead to longer curing times. However, curing time wasnt necessarily the issue- it was the weight and the fact the foam wasn’t adhering to the glass.

I do like the foam board idea. Just getting the branches and wood to stick out properly will be tricky. 

thank you again for the great advice!


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## jgragg (Nov 23, 2009)

You're quite welcome. I don't keep frogs, I keep snakes, but a lot of what I do is completely applicable to what most DB'ers are here for - exchange of reliable knowledge.



> I actually did it after watching a SerpaDesign video


I want to be careful here. I'm not throwing anyone under the bus. But I have watched a number of online videos from that shop and others on vivs, and - *exactly the same* as if you're watching online videos about how to roof a shed, replace a sink, fell or buck a tree, or rebuild a carburetor - just because you see somebody do it on the YouTubes doesn't mean they're absolutely right.

My inherent suspicion probably is operating here. But I'm not sure how many of those guys who probably are earning from clicks, likes, or whatever, _are actually long-term viv makers & humid-herp keepers_, with long-term experience with operation, durability, fails, upgrades, tear-downs and rebuilds, etc. Versus basically "porn directors" who deliver money shots but nothing of lasting, healthy satisfaction due to earned wisdom & experience. If that makes sense. Could just be me, there's a touch of grumpy old asshole in me.



> I do like the foam board idea. Just getting the branches and wood to stick out properly will be tricky.


Indeed. You can play around with some disposable mock-ups on the bench, that will never go into a viv, to play with desired aesthetics and required technique. My usual approach now is to bench-build background components that will "jigsaw-puzzle" around the branch ends. (Snakes = horizontal perches, not stuff coming up off the ground.) I first either silicone (in case of glass viv) or glue & screw (in case of plywood viv) at least 2 and preferably 3 attachment points on my perches. Then I install either 1) the pre-fab foam components or 2) my cracked-cork mosaic, around those attachment points.

Good luck, have fun!


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## Scags (Oct 9, 2011)

jgragg said:


> You're quite welcome. I don't keep frogs, I keep snakes, but a lot of what I do is completely applicable to what most DB'ers are here for - exchange of reliable knowledge.
> 
> 
> I want to be careful here. I'm not throwing anyone under the bus. But I have watched a number of online videos from that shop and others on vivs, and - *exactly the same* as if you're watching online videos about how to roof a shed, replace a sink, fell or buck a tree, or rebuild a carburetor - just because you see somebody do it on the YouTubes doesn't mean they're absolutely right.
> ...


I know what you mean with the YouTube videos. I agree, some of the videos by said YouTubers are these unrealistic setups that aren’t built for long term growth- and the videos are created for financial gain. Some interesting videos and ideas, but lack of follow ups tells me those vivs don’t last long, and problems arise.
I actually don’t keep frogs myself anymore. Years ago I kept tree frogs and geosesarma crabs. Most of my tanks are just for plants. I love the way they look, and I’m a bit of a plant geek. 
Ive been doing vivariums and terrariums for a long time myself. Just hadn’t ever done the foam thing because I was always about using natural products only in my vivs- obviously accept for the tank itself and lighting.

I also kept Indonesian tree boas in one of my tanks for several years. That was an arboreal tank with lots of ficus pumila and kangaroo ferns. 

Recently though I was contemplating getting some dart frogs Or dwarf geckos. Haven’t decided yet, not sure how suitable a super tall tank would be for either of them. I need to do more research before i do anything in terms of adding living creatures to the tank.

sorry just rambling on now.

I’m an old grumpy asshole myself, so no offense taken, haha.

However, despite my older age and “wisdom” I still tend to rush things when I shouldn’t. I think it’s just the fact that I work all week, and then on the weekends I try to get as much done as I can. So I end up rushing, and make mistakes that could have been avoided has I been a little slower and more methodical in my approach.

pretty sure my wife could attest to this. Haha.

anyhow, thank you for the words of encouragement and wisdom. I’ll post pics in the members section once I have it redone and it’s grown in a little. Going to try to do something similar to what I have- just with a better more secure background.
Need to order some more plants too. I want to get some orchids in there, and some huperzia.
Also going to build a custom top to hide the Wack lighting setup I’m using. 2 6500k 30w Led flood lights And 2 6500k 23w cfls. It’s horrible looking.

thanks again!


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## mille981 (Sep 9, 2008)

Scags said:


> Anyone?


Marine grade chemlink m-1 is all I use for terrariums. It will cure when wet and has many times more holding strength than silicone but is very expensive and much thicker. It will also bond with plastic, epoxy, glass and metal, unlike silicone. Search for it from online building supply stores to find a reasonable price. You can spread it in back and then fill the edges.
I don’t use great stuff except as filler under zoopoxy. I have tanks that have lasted 10-15 years until I finally just wanted to change them. I use polystyrene foam and carve it with a hot knife. Then I glue it in place and cover it with zoopoxy or m-1 and treefern. I leave areas blank for treefern panels. I have used the m-1 with stainless steel brackets and wing nuts to glue raised panels, wood and heavy items.


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## Scags (Oct 9, 2011)

mille981 said:


> Marine grade chemlink m-1 is all I use for terrariums. It will cure when wet and has many times more holding strength than silicone but is very expensive and much thicker. It will also bond with plastic, epoxy, glass and metal, unlike silicone. Search for it from online building supply stores to find a reasonable price. You can spread it in back and then fill the edges.
> I don’t use great stuff except as filler under zoopoxy. I have tanks that have lasted 10-15 years until I finally just wanted to change them. I use polystyrene foam and carve it with a hot knife. Then I glue it in place and cover it with zoopoxy or m-1 and treefern. I leave areas blank for treefern panels. I have used the m-1 with stainless steel brackets and wing nuts to glue raised panels, wood and heavy items.


ha! Thanks for the response. I actually just used this to secure the new background. It wasn’t too expensive, and worked like a charm. 
I was able to salvage my background as it came out in one big piece. I broke it up into smaller sections and secured them individually using chem link m1.
Afterwards I tried hand pulling the sections off- and they did not budge- at all.
Thanks!


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## Harpspiel (Jan 18, 2015)

For future reference, I created a self-supporting and removable GS waterfall using egg crate zip-tied together as a base, and then GS in layers on top. The egg crate provided a rigid frame and I was able to carve the GS and embed rocks to create a cascade. I created it outside the tank, and the GS expanded out through the back of the egg crate (the corner that would be pressed up against the glass), but I just let it cure like that and then sawed it flat with a serrated knife once it was done curing. It was very effective (although I wouldn't recommend making it removable if you're keeping frogs, they would probably get stuck behind it), and it holds itself up without any sagging.


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