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Discussion Starter · #1 ·
I added the foam last week to the aquarium as a background, and i have a feeling its still curing from the inside. Every once in the while i hear noises coming from the tank; sort of like a tree branch cracking. Either the foam is expanding from the inside, causing ripples to the hardened outer layer. Or the foam is adding pressure to the glass, and quite possibly breaking it.

Does anyone know when the foam completely cures. And will poking holes throughout it speed up the curing?

Thanks.
 
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the foam should cure completely in 24 hours but correct me if im wrong. and the cracking you hear is probably breaking the glass because i had some experience with it, the first time i foamed a tank i put to much and i ended up break a hole about 9 inches wide so the next time your going to foam i recommend you doing it little by little, its worth the wait.
 

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Discussion Starter · #4 ·
I dont think the glass cracked. Well, i cant find any cracks or streaks.

Im convinced it was the foam expanding inside, because i poked a few holes a few days ago. And overnight, long foam "branches" oozed out and hardened.

M.N
 

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It could be that the outside hardened before it could expand anymore and maybe cracked the outside layer in order to expand, that would explain your relief holes.
 
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type of foam

i' ve been hearing a lot about greatstuff and it's uses here and in other forums. It's bad stuff, for vivarium-aquarium use at least.
i think the issue is that the foam is starting to break down, if it is Great Stuff you're using. if not, the noise might be from air being expelled from the foam, that pulling the foam off the glass.
the best foam i've used, for a year now, is black, water proof and safe for herps and fish. it's three times a much in some areas but it won't break down in water like Great Stuff does.

what type of foam are you using?
 
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Poking Holes..

if you poke holes in any type of expanding foam, you weaken the integraty and increase the chance of structural failure-collapse. when foams claim water proof, it's the outer layer, the hard shinny outside. when you cust or poke through this, letting water into the inside, the foam fails. it's hardening stops and the gasses that are created by the chemicals to sort of Cook the product, are let out, thus making the foam weak.
 

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Just something to think about. The Great Stuff I and many of the people use on this board is a moisture cure urathane foam. Its water proof all the way through. You will get a faster cure and stronger foam if you mist it with water as you put it down. This is expecially true for people in very arid climates where they don't have the moisture in the air needed for the foam to cure properley.

If I understand it correctly the gasses that are used to inflate Great Stuff are not the product of any chemical reaction going on in the foam, but are are VOCs like methane or propane, which are easily compressable. This is why you get better expansion of the foam if you follow the package directions and shake the can before useing, ensuring the liquid "gasses" are well distrubuted through the foam.

There are latex foams out there that claim to be water resistant and cure in 24 hours. They are niether. I experimented with these once. After a week of curing, a few seconds under water was all it took to dissolve the foam.

It is my understanding that the black foam used for ponds is virtually the same as the urathane foam produce by Great Stuff, with the exception that they claim it cures harder/stiffer. I haven't worked with the black foam at all nor have I seen it used in person, but it probably does cure harder/stiffer as that would be benificial to the application it was designed for. I think for most purposes it is only a matter of aesthetics to use the black foam over Great Stuff.
 

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Many, many people have used Great Stuff to make viv backgrounds, and I hear very few complaints about it. You see tutorials on how to use it online, people use it here, on frognet, and even on kingsnake and have had no problems. IMHO, it is good as long as you allow it to cure properly, it is fine. Also remember that most people smear it with silicone to adhere the coco bedding, which makes it even more waterproof.
 
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Arklier said:
Many, many people have used Great Stuff to make viv backgrounds, and I hear very few complaints about it. You see tutorials on how to use it online, people use it here, on frognet, and even on kingsnake and have had no problems. IMHO, it is good as long as you allow it to cure properly, it is fine. Also remember that most people smear it with silicone to adhere the coco bedding, which makes it even more waterproof.
in all Hazardous Material Data Sheets, the main ingredent in Great Stuff will break down when in contact with water. thus releasing from it's chemical moca, a oxigen suppresion gas, i can't spell it. it is just my opinion, i've alread discussed this concern with scott of frognet so i'm not interested in discussing this again. greats tuff is just a good product, there is better products out there, and i think i'd rather spend more for my animals safety
 

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Not to drag out something you don't want to disscus Terra5, but the main chemical in Great Stuff is polyether polyol which uses water as an intiator to form the chains that make up the foam. If I understand the chemistry correctly it strips a hydroxyl group from the water, which is a reaction that is not easily reversed by adding more water (ie not water soluble).

Not to sound ignorant here, but what is a chemical moca? I am unfamilar with the term.
 

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Moe, i've used it a few time and one time had a issue with it not drying in the middle, here is what I came up with.

1. I have yet to be able to reuse a can after it was started so if you did this it may be the issue. What seems to happen is that the "stuff" from a already used can never seems to dry, not sure if it is related to it not sealing right after being used.

2. It is a good idea to do it in layers, letting each layer dry first. This also makes the 1st issue a bit tough.

3. I have found it easier to make the rough structure with styrofoam (siliconed in place), and then fill in the gaps with great stuff, this takes less great stuff and in most cases only one layer.

For your issue I would drill holes in it to allow air to get the middle though it may take a long time to dry now. I actually had to remove half of mine and get a new can and start over when I had the issue. If you plan on having a water feature you may want to go this way, as some of it may never dry. I was able to tell by sticking a long nail in it and it came out with sitcky uncured great stuff on it.

As for it being unsafe I rememeber a number of people posting that as long as it is 100% dry it is 100% non-toxic. I have it in 3 of my tanks, and have had NO issues at all, 1 of which that has been up and running for over a year. I also have stryfoam backgrounds covered with weldbond\cocofiber in 5 tanks with no issues, though this method takes a long time to dry.

Hope that helps, let me know if you need anymore info...
 
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Moca...

Moca is a term given to a mixture of chemicals to make a solid. for eample, urathane has to mixes, one for firmness and one for strength. when you mix these two groups of chemicals for the mold oven, it's called moca. moca, milk, coffee, chocolate...it's just an industry term. i built skateboard wheels long ago.
 
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