# Gorilla glue or silicone for 3D background?



## driftwoodhunter (Sep 10, 2011)

I am in the process of making my first 3D backgrounds, and I am having a blast! 
I have noticed that the blue insulation sheet styrofoam that I'm mostly using is flat and slick (or polished looking - and yes I removed the thin plastic sheeting that it's coated in) and the dried silicone is easy to peel off if it oozes out. So I'm worried that if I use silicone (GE1) to adhere the foam to the back & edges of the tank's glass, the force of wanting to float will pull the silicone off the foam - leaving silicone on the glass, but without the BG attached. 
I can think of two possible solutions; rough up the back of the foam to give 'tooth" to it for the silicone to get a good grip, or use Gorilla Glue. I've been experimenting with GG on rocks, driftwood, and even for glueing foam to foam - I love the product. But will it adhere the foam to the glass?
I was hoping someone would have first-hand experience to share...
I'm also going to GG some real rock to the lower part of the BG at the substrate line, to help weigh it down...
btw, the Drylok totally seals the exposed silicone on the 3D BG, so I'm not worried about the foam pieces separating. In fact I wonder if I can use the Drylok between the foam sheets and shapes to stick them together, rather than silicone? These BGs that I'm starting with are for two 29g tanks - they are my experiment/learning curve for two 55g tanks I'll be doing, too.
Many thanks for any & all help!
Cindy


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## Rick_Lindsey (Aug 26, 2002)

I personally would lean away from using the gorilla glue on the glass... I imagine it would be MUCH more difficult to remove than silicone if anything went wrong, or if you changed your mind later. Granted removing large quantities of silicone is no easy task either!

-Rick (the armchair aquarist)


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## mightyevil (Oct 23, 2008)

I completely agree with Rick, I would refuse using gorilla glue on glass. I think it would take a gorilla :lol: to take that glue off the glass once dried (could be wrong because I have never tried gorilla glue on glass but I have tried it on other things and it was not fun trying to remove it) . I have made a good handful of backgrounds and I have removed backgrounds before because I would get bored of the old ones so thinking about the future, you might want to make the job easier on yourself. I have never used blue styro but I have seen other people use the pink and blue with success, no reason why you couldnt... :thumb:


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## driftwoodhunter (Sep 10, 2011)

Thanks guys - I never thought about how hard it would be to remove! (if removable at all). 
I'll rough up the back of the blue insulation and gouge a few spots in it for the silicone to grip into - thank you for responding to my question!


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## Bungalowdan (Aug 16, 2010)

I've built a few. In my experience, using silicone to hold foam to foam didn't work well. I'd carve it with a surform tool, and it would "grab" the silicone and pull it from between the sheets. I also tried Drylock as an adhesive, which held well, but it is much harder than foam and difficult to carve. Third time is a charm as gorilla glue bonds and carves well.

As others have mentioned, Gorilla glue to glass is a bad idea, because it will be difficult to remove. I sanded the part that would adhere to the glass with 80 grit, and coated with drylock (and of course, allowed it to dry prior to installation). Between the sanding and drylock, there appears to be plenty of "tooth" for the silicone grab. I actually tore one out of my 20 long, and as much effort as that took (e.g. it came out piece by piece and with a lot of scraping and cursing), I am positive there is no way it would have come free just from the bouyancy forces.


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## driftwoodhunter (Sep 10, 2011)

Thanks, Bungalowdan - 
I wondered about the quality of adhesion between Drylok and the glass with silicone. I didn't know if it would hold, but I didn't want to see the ugly blue edges of the insulation up against the side glass - so I coated the sides of the BG foam with the Dryok. I was afraid I'd made a mistake and the Drylok might peel off once siliconed to the glass. It's good to know I can coat the back of the BG with Drylok too.
Since I precut the big shapes out, precarved them, and then siliconed them together, I think I could skip the silicone and "glue" up the precarved pieces with the Drylok. I'm thrilled with how easy it is to use. 
Thinking ahead...how long should it cure before I can add water to the tank? Is it good to go once it's thoughly dry?


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## driftwoodhunter (Sep 10, 2011)

PS - If someone can help this computer know-nothing figure out how to post pics, I can show you what I've done so far! lol


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## mightyevil (Oct 23, 2008)

driftwoodhunter said:


> PS - If someone can help this computer know-nothing figure out how to post pics, I can show you what I've done so far! lol


Use one of those free online providers like photobucket and such. Upload your photos there and then all you do is copy the image code and paste it here. It is that simple!


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## Bungalowdan (Aug 16, 2010)

driftwoodhunter said:


> Thanks, Bungalowdan -
> Thinking ahead...how long should it cure before I can add water to the tank? Is it good to go once it's thoughly dry?


I let the drylok dry overnight, then siliconed it in, then let the silicone cure 24 hours. Then I added water, turned on the equipment, tweaked the jets, added sand, ran 24 hours, drained, & repeated running it for 48 hours. I kept an eye on temperature to make sure I was getting good water circulation since the heater is hidden behind the BG. Then I drained again and added fish & an established filter, plus about half of the water from the tank they were in while I rebuilt the tank. My method may be ovekill, but it worked well for me multiple times, so I'll stick with it!


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## driftwoodhunter (Sep 10, 2011)

Thanks, Bungalowdan - I have the heater in front of the BG, it will be suctioned to the side glass - mine BG is going to be siliconed flat against the back glass, and I'm using HOB filters on the tanks - I'll fill & drain following your schedule...I'm ok with overkill ; )


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