# Great stuff not sticking to silicone?



## Alexmenke92 (Nov 19, 2013)

It sounds like a newbie question because it is. In all of the tanks I have done I usually do not do a layer of silicone right on the glass and then great stuff. I have done it before though and it worked fine. I did the layer of silicone because the foam did not stick well directly to glass. Well...now I'm having an issue. I have two 20H that I am doing and three sides have fully cured silicone 1 on them. I foam a side..wait a day...then it starts peeling off! Its beyond frustrating because I am wasting materials redoing things and I have no idea why its happening. Any help?


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## PDFanatic (Mar 3, 2007)

Make sure you're shaking up your foam very well before use or it won't stick.


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## oddlot (Jun 28, 2010)

Also see if there is an expiration date on the can. I've heard about this happening when the good stuff was too old.


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## Bryanmc1988 (Jun 22, 2014)

this is more command then you will know... i had done my GS background also and it started peeling off from the glass.... no idea why... when i look at my foam from the back i can see big air bubble gaps away from the foam and the glass. Funny as it may sound i did layer by layer and waited 24-48 hr before laying down a new layer also but still ended up having problems


what i ended up doing was filling the edge of all the foam with a silicone bead all the way around the foam this should keep the foam from getting humidity behind the foam and keep the foam from peeling off... GS is not cheap when u need 4+ cans for 1 tank... then have to redo it again... GS = Silicone both cost money -.- and time...


i say glue that thing back with glue or more silicone and call it a day...


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## oddlot (Jun 28, 2010)

I only use cork slabs for these reasons.You can't have these problems and it looks awesome!


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## PDFanatic (Mar 3, 2007)

This doesn't happen frequently actually. I have made hundreds of tanks, I apply great stuff directly to glass. 2 times out of all these applications did I ever have problems and it was due to me not shaking the cans of great stuff. I have never had the great stuff peel off the glass or anything. As a matter of fact I have a tank in front of me now that is just fine.


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## s0082 (Jun 22, 2014)

I have done 4 vivs this past week and one of mine separated too, the other 3 and none of the others Ive done have... wonder if I didn't shake the can?? THanks for the tip. and I might look into cork backgrounds too lol


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## PDFanatic (Mar 3, 2007)

I apply great stuff to the glass then stick cork slabs to it...








I have no problems ever with the foam separating...


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## Alexmenke92 (Nov 19, 2013)

Hmm...understood. Perhaps it is only because I did not shake it well enough although I usually make sure I do...guess I'll just shake it twice as long! I appreciate all the feedback guys, that really helps me. I'm doing rock walls with drylock and its taking so, so long. Especially having his problem so early in the process.


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## rigel10 (Jun 1, 2012)

GS adheres better if you moisten with a handsprayer the glass - but I use a piece of styrofoam that I put with a bead of silicone to the glass and I cover it with foam.


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## Judy S (Aug 29, 2010)

It may also help to clean the glass initially with alcohol....


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## wak4863 (Jul 26, 2012)

Why would you let the silicone cure before applying the GS? I would think you want the Silicone and the GS to bond while they cure together. That may mean a longer cure time but I would think it will be a better result. 

If I'm wrong about the process let the public flogging commence. 



Alexmenke92 said:


> It sounds like a newbie question because it is. In all of the tanks I have done I usually do not do a layer of silicone right on the glass and then great stuff. I have done it before though and it worked fine. I did the layer of silicone because the foam did not stick well directly to glass. Well...now I'm having an issue. I have two 20H that I am doing and three sides have fully cured silicone 1 on them. I foam a side..wait a day...then it starts peeling off! Its beyond frustrating because I am wasting materials redoing things and I have no idea why its happening. Any help?


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## oddlot (Jun 28, 2010)

I don't ever use gs but I would think it may not cure correctly or at all if the air can't get to the silicone being it's covered by the gs, and may peel for this reason. I'm purely speculating on how I think it would react, because as I said I don't use it.


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## PDFanatic (Mar 3, 2007)

Lou, what do you use?


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## oddlot (Jun 28, 2010)

Just cork slabs.No glues,silicone, or gs. I like to keep it all natural.


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## gregs4163 (Jul 11, 2014)

I'm having the same issue, mine is separating from the left & right side of my background. I have about a 1/4" gap between the glass and the foam now, I'm thinking of filling the gap in with something silicone maybe but I want to wait until the shrinking subsides. I accidentally purchase this water based caulking thinking it was silicone I'm thinking of using that but I'm not sure if it's ok to use. Has anyone seen or used this? is it safe to use?

https://fbcdn-sphotos-h-a.akamaihd...._=1406667256_3a25647396a467741f266e3179ee1b9e


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## PDFanatic (Mar 3, 2007)

Greg, I wouldn't use it....


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## gregs4163 (Jul 11, 2014)

Thanks for the quick reply  I may just leave the gap then, it not that bad, and probably wont be all that noticeable once it's planted. I just hope it doesn't get any worse, it's sucks how much it shrank


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## Judy S (Aug 29, 2010)

just out of curiosity..has anyone gone back to the earlier threads about using GS, Gorilla Glue and silicone? There have been umpteen posts and instead of reinventing the wheel...why not go back and read the history...?


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## Frog Town (Oct 8, 2013)

PDFanatic said:


> This doesn't happen frequently actually. I have made hundreds of tanks, I apply great stuff directly to glass. 2 times out of all these applications did I ever have problems and it was due to me not shaking the cans of great stuff. I have never had the great stuff peel off the glass or anything. As a matter of fact I have a tank in front of me now that is just fine.


I don't mean to hijack the thread but have you ever adhered the cork slabs to the glass with just silicone and then filled in the spaces in between with more silicone?

Would this work just as well? I've always been curious as to the long time holding ability of just silicone in a wet and humid environment.


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## Alexmenke92 (Nov 19, 2013)

I think this was my mistake. I didn't remember how I did it last time for some reason. Most of the time I use foam or stick cork or something else straight to silicone. 


wak4863 said:


> Why would you let the silicone cure before applying the GS? I would think you want the Silicone and the GS to bond while they cure together. That may mean a longer cure time but I would think it will be a better result.
> 
> If I'm wrong about the process let the public flogging commence.


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## Alexmenke92 (Nov 19, 2013)

Yes and this works well. Silicone to silicone isn't always a good idea but it CAN bond because I've done it, the bond is just weak. I did cork to silicone and it worked just fine because silicone adheres to glass really well.



Frog Town said:


> I don't mean to hijack the thread but have you ever adhered the cork slabs to the glass with just silicone and then filled in the spaces in between with more silicone?
> 
> Would this work just as well? I've always been curious as to the long time holding ability of just silicone in a wet and humid environment.


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