# Fail!



## SLiK JiM (Oct 10, 2011)

Well, I'm glad I tried this out first!

Basically, I wanted to build a very large enclosure so I went with what I had read on a UK forum and was going to try using polycarbonate sheets. I made a 'test' enclosure added some water, and within a few minutes had a leak. I looked at the silicone and it really hadn't bonded to the sheeting really at all! Some areas where it was a little 'rougher' seemed to hold up pretty well, but it the most part it peeled off very easily.

Anybody got any ideas? I'm pretty close to jacking it in and going with all glass, but boy would it be heavy!


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## Darts15 (Jun 5, 2011)

Well, you could always try sanding around the parts you are trying to bond together to get more traction. You could also look around for a different sealent of some sort...maybe some kind of plumbing sealent that will stay better on plastics and such.


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## SmallScaleDan (Nov 16, 2008)

Try using a two part marine epoxy. It's available at any home depot. It's not cheap, but it will bond with the plastic, and It's sandable. When dry it is completely inert. 

Dan

PS, I would still sand the areas you plan to bond even with the epoxy.


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## Ed (Sep 19, 2004)

The best product is going to be one of the weld on products like weld on 16 or 40 (acrylic cement). Silicone doesn't adhere well to acylic and tends to rapidly fail. 
If you use the weld-on products above, they actually create a chemical bond causing the acylic sheets to actually polymerize together however, if you aren't using thick enough acylic, the weight of materials (water, substrate etc) in the enclosure can cause enough flexing of the sides and bottom that the bonds can still rupture. 

Some comments

Ed


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## Pacblu202 (May 8, 2012)

If polycarbonate is similar to acrylic its very hard to work with because 90% of the stuff you try to stick to it/it to doesn't stick


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## Pumilo (Sep 4, 2010)

I used to work with acrylic professionally. Ed is right. You want an acrylic cement. Weld on 16, 40, and 4 are the most commonly used. All cuts and edges must be perfect to use Weld On 4 as it will not fill any gaps.
No sanding of surfaces is necessary unless you do a hack job on your cuts.


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## SLiK JiM (Oct 10, 2011)

Ed said:


> The best product is going to be one of the weld on products like weld on 16 or 40 (acrylic cement). Silicone doesn't adhere well to acylic and tends to rapidly fail.
> If you use the weld-on products above, they actually create a chemical bond causing the acylic sheets to actually polymerize together however, if you aren't using thick enough acylic, the weight of materials (water, substrate etc) in the enclosure can cause enough flexing of the sides and bottom that the bonds can still rupture.
> 
> Some comments
> ...





Pumilo said:


> I used to work with acrylic professionally. Ed is right. You want an acrylic cement. Weld on 16, 40, and 4 are the most commonly used. All cuts and edges must be perfect to use Weld On 4 as it will not fill any gaps.
> No sanding of surfaces is necessary unless you do a hack job on your cuts.


Thanks both, Weld on 16 looks to be the stuff, but sadly it doesn't look to be available in the UK... Typical!

I'm trying to find something similar over here and the only thing I have stumbled across thus far is this:

FloPlast SC250 Solvent Cement 250ml | Screwfix.com

I just don't think it is suitable.

I've found a website called 'shop4glue.com' who look like they might sell the stuff I need! I will drop them an email!


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## SLiK JiM (Oct 10, 2011)

Does this look to be the stuff?

Polyweld thick gap filling plastic cement glue for acrylic abs perspex lucite model glue etc


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## SLiK JiM (Oct 10, 2011)

Well, I never heard back from that website, so I went and tried some other stuff out and it worked! I used silicone that would work 'on wet surfaces' (I think it's used with koi carp but I'm not 100%) and it worked a treat. When comparing it to the other silicone it was considerably 'thicker' and 'tackier' but dried completely very quickly! I'm going to proceed with this silicone but will test it out a lot before I finish the build a put it into use!

Thanks all!


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## goof901 (Jan 9, 2012)

i believe polycarbonate will leach bad stuff into your viv... This thread applies to the top of a viv, but i think the same will occur if you use it on the sides. http://www.dendroboard.com/forum/parts-construction/80722-lexan-top.html


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## Pumilo (Sep 4, 2010)

SLiK JiM said:


> Well, I never heard back from that website, so I went and tried some other stuff out and it worked! I used silicone that would work 'on wet surfaces' (I think it's used with koi carp but I'm not 100%) and it worked a treat. When comparing it to the other silicone it was considerably 'thicker' and 'tackier' but dried completely very quickly! I'm going to proceed with this silicone but will test it out a lot before I finish the build a put it into use!
> 
> Thanks all!


It's not going to work long term. Silicone absolutely does NOT form a permanent bond with most plastics. It will hold long enough for you to think that it's going to hold, but it will fail at the worst possible time.
You need to determine if it is polycarbonate or acrylic, then get a solvent style glue made for that.
Make sure to check out the thread goof linked you to, so that you can make an educated decision about using polycarbonate.



goof901 said:


> i believe polycarbonate will leach bad stuff into your viv... This thread applies to the top of a viv, but i think the same will occur if you use it on the sides. http://www.dendroboard.com/forum/parts-construction/80722-lexan-top.html


That's a good point. Are you sure you are working with Polycarbonate/Lexan, and not the more common Plexiglas/Acrylic?


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## Ed (Sep 19, 2004)

SLiK JiM said:


> Well, I never heard back from that website, so I went and tried some other stuff out and it worked! I used silicone that would work 'on wet surfaces' (I think it's used with koi carp but I'm not 100%) and it worked a treat. When comparing it to the other silicone it was considerably 'thicker' and 'tackier' but dried completely very quickly! I'm going to proceed with this silicone but will test it out a lot before I finish the build a put it into use!
> 
> Thanks all!


As Doug noted, there is a good chance it will fail... Years ago, I had a front opening tank conversion that had the bottom panel made from plexi and held into place with silicone... After about six months the whole panel popped off, spilling the water onto the floor (lucking the false bottom was above that point so the inhabitents didn't escape.. Up until the fail it looked like it was solid and going to hold. Your really rolling the dice as to whether it lasts or not. 

Ed


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## SLiK JiM (Oct 10, 2011)

Right,

It's certainly polycarbonate sheeting (the type used for greenhouses etc).

Coming across the right stuff over here in the UK is proving to be a massive pain in the ****! We just don't seen to have any acrylic cement type products.

I've found this: Polycarbonate Sealant Clear 310ml - Sealants - Tools, Electrical & Plumbing - Wickes which would seem to be a silicone designed specifically for polycarbonate sheeting?

I'm going to try and find myself a polycarbonate solvent/glue but it doesn't look likely!


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