# Great STuff and Acrylic???



## Ben_C (Jun 25, 2004)

Hey all, 
Do any of you know if you need to put a silicone layer on the back of an acrylic tank to get it to adhere to great stuff foam?
Thanks,
Ben


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## Ed Martin (Mar 25, 2004)

I did. The silicone smell stayed in the acrylic enclosure for a LOT longer too. I think some other people had the same expierence, there was another thread about it. 
Ed


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## Ben_C (Jun 25, 2004)

Hmmm....I was hoping to not use silicone....sorry to post about something that has already been discussed. I will do a more detailed search on the subject.
~B


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## Mantellaprince20 (Aug 25, 2004)

hey ben, if you use the Aquarium Silicone that is made for fish tanks, I doubt you will have a problem. It loses its smell within 2 days. Just a though,

Ed


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## Darks!de (Nov 16, 2004)

It is a bit more expensive however.

Luke


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## Schism (Nov 12, 2004)

I did my tank without any silicon on the acylic. I have some moderately heavy pieces of wood as well.


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## Marty (Feb 27, 2004)

I wouldn't use silicone. It appears to adhere to plexi for a bit, then it will release and you will be up sh$% creek. All my setups, I use course sand paper, score/scratch the surface where the background will go, then I use drywall fiberglass tape and stick it to the scored acrylic. I roll that so it's adhered nicely. Then on top of that I go with the great stuff foam. It holds very well...

The scratching was suggested on some other thread by Rich Fry I believe. It's a very good tip that works. It gives great stuff a coarser surface to hold on to, other then the nicely polished glass like side.

As an alternative I also heard someone bonding irregular (hooked, heat bent, etc) small pieces of plexi with methylene chloride to the acrylic then once dry applying great stuff over it. Little pieces act as anchors and even if it will let go from the backing, the whole background will be well held by all these small pieces.

EDIT: I should add that you go with the weldbond, soil mix on top of the finished, carved, root embeded, etc structure once it's all dry.





Ben_C said:


> Hey all,
> Do any of you know if you need to put a silicone layer on the back of an acrylic tank to get it to adhere to great stuff foam?
> Thanks,
> Ben


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## Dancing frogs (Feb 20, 2004)

Marty said:


> I wouldn't use silicone. It appears to adhere to plexi for a bit, then it will release and you will be up sh$% creek. All my setups, I use course sand paper, score/scratch the surface where the background will go, then I use drywall fiberglass tape and stick it to the scored acrylic. I roll that so it's adhered nicely. Then on top of that I go with the great stuff foam. It holds very well...
> 
> The scratching was suggested on some other thread by Rich Fry I believe. It's a very good tip that works. It gives great stuff a coarser surface to hold on to, other then the nicely polished glass like side.
> 
> ...


That makes sense...I still need to try using poly-eurethane (elmer's pro-bond, gorrilla glue) adhesive for this. I used that for my glass verts, and it worked real well.
You could also screw/bolt the cork to the acrylic if you wanted, since acrylic drills so easy.


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## Blort (Feb 5, 2005)

I'm pretty sure the brand name aquarium silicone is just GE IS808 based on a comparison of Material Safety Data Sheets. IS808 is food grade silicone and is the only one tenatively recommended by GE for underwater applications (reference same link). You can get a 10oz caulk gun tube for abou 5 bucks versus 15 for the aquarium silicone. I am fairly certain that aquarium sealant is just repackaged stuff from an upstream manufacturer like GE or DoW. I haven't checked, but I don't think that there are more than a handful of places that acutally make the silicone.

I thought that the fumes were still pretty noxious, but I was using a fair amount in a small tank (20g). I certainly recommend doing the work outside. I also used a 3M respirator with organic vapor cartridges which are 100% effective in blocking the fumes and neoprene gloves for my hands. I'm probably a bit paranoid :shock:, but I used to work around hazardous chemicals for a living and am an OSHA authorized instructor, so its hard for me not to do the same things at home.

Sort of off-topic, but thought it might be usefu.

Cheers 

Marcos


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## Ed (Sep 19, 2004)

You can use gel superglues to adhere plexi to acrylic just be warned that it will form a permanent bond if done right. 

Ed


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