# Silcone sealants not sticking



## Imperial_Aquatics (Aug 27, 2009)

recently I built 40+ Dart tanks, based off of tanks I picked up on the cheap at the local Petsmarts (plural)

Fortunately none of these tanks were intended as verticals otherwise I'd have been screwed. 

WHY???

Because I used standard Aquarium silicone sealant to glue the glass pieces for the lids, as well as the window screen frames I built to the plastic trim on the tanks. 

All items were thoroughly cleaned and dried before gluing. 

Not a single one stuck together. At the slightest touch, the glass knocked out of place. The silicone held tight to everything except the plastic frame of the tanks. 

Which kind of surprised me. 

I tried to repair a couple of the tanks that didn't have frogs in them yet by scuffing up the surface of the plastic and then re-glue it. No luck.

It strikes me as really odd that standard silicone sealant wouldn't stick to the plastic frame. Maybe liquid nails???


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## frogfreak (Mar 4, 2009)

That' weird!

I put glass in all my Exo lids. I clean the plastic with rubbing alcohol and use GE silicone. It works fine.


I would try different type of silicone...


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## Imperial_Aquatics (Aug 27, 2009)

frogfreak said:


> That' weird!
> 
> I put glass in all my Exo lids. I clean the plastic with rubbing alcohol and use GE silicone. It works fine.
> 
> ...



yeaaaaahhhhhh.... did that.

This started with me using GE II black silicone to glue everything in. Then after having read hundreds of threads extolling the virtues of GEII, I find a thread or two that go into great detail why GEII is bad and you shouldn't use it. 

That was actually how I discovered that it didn't stick, because I was going back and re-doing the tanks I'd used the GEII on. Touched the lids and POP!! off they came with no pressure required.

Recently I also tried the DAP silicone after my cases of it arrived. 

Same issue. Absolutely would not adhere to the plastic trim on the Petsmart tanks. 

Of course now all of those tanks are full of frogs and I can't go back and mass re-glue everything.


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## jon (Mar 12, 2008)

Off the shelf silicone doesn't stick well to plastic. I mean, it will create a seal, but any amount of torque will dislodge it. There are specific silicone sealants made for plastic and plexiglass, but I don't know how well they stick to glass. So long as the stuff you used is keeping things water-tight, you're okay. I'm not very familiar with aquarium silicone, so my commentary is based on the GE II, DAP, etc.

Oh... and you may have just gotten a bad tube/batch of silicone.


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## frogfreak (Mar 4, 2009)

I don't know what to say. I know I would be pissed.

It has to be the type of plastic the frames are made of IMO.

For instance UHMW. NOTHING will stick to it. I can't imagine that the rim of a tank would be made of a special plastic though.

There is a silcone, made for Lexan at Lowes that might be worth a shot. It dry's crystal clear.

The tube is only 2.8 fluid ounzes. It red in colour. Called Lexan. Made by GE.

Says it will bond metal, glass and *most* plastics. It's in with the lexan materials. Where they cut it.


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## Petersi (Jan 31, 2008)

Do you have any pics? I use CRLawerence silicone all the time and I dont have any problems with my tanks.


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## Imperial_Aquatics (Aug 27, 2009)

frogfreak said:


> I don't know what to say. I know I would be pissed.
> 
> It has to be the type of plastic the frames are made of IMO.
> 
> For instance UHMW. NOTHING will stick to it. I can't imagine that the rim of a tank would be made of a special plastic though.



this was pretty much my thought as well.

Kinda weird 3 different sealants refused to stick to any of the tanks.


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## prolawn_care (Dec 26, 2009)

If nothing else try gorilla glue. Or if you have lots of free time you could go through and drill holes in the glass and the plastic rim and use plastic rivits to hold it from falling off with pressure, but not so sure it will do the trick as far as water tightness... But i suppose you could re silicone it inside and out.

Also not sure if it would work of not, but possiably some PVC glue might work, but would look ugly with the purple primer...

Whatever you end up doing let us know what works best for you!


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## tachikoma (Apr 16, 2009)

Gorilla glue works on ANYTHING! It is ridiculous how strong it is also. I glued a piece of metal to a slab of concrete once and years later I went to remove it the concrete broke before the bond broke! Whatever your plastic is made of there is something that will stick to it. Just got to find the right stuff.


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## Imperial_Aquatics (Aug 27, 2009)

prolawn_care said:


> If nothing else try gorilla glue.


I have something Gorilla, but as I recall it foamed up like crazy. looks like dark honey when wet. Expands a bit as it dries.

Since I had frogs in the tanks already, I'm kinda stuck as far as trying a new glue goes. It'll be a very logn drawn out process moving frogs and doing tanks one at a time until they are all done.

At the moment, my solution is the simplest I could come up with, I used electrical tape. The frames were black, so it's pretty much invisible. 

This will just have to suffice until I do my planned upgrade in a few months.


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## prolawn_care (Dec 26, 2009)

Are you looking for water tight? If so they also sell marine epoxy in a stick form all you have to do is mix it up and apply! You could probably put it on the outside and make off where you want to stay clear and use viv safe spray paint to paint it....

Those are just a few suggestions... Theres several options, but like you say the problem is that the frogs are already settled in and to disturb them would most likley stress them out.

Good luck!


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## Imperial_Aquatics (Aug 27, 2009)

Ok, I'm starting this with a slight vent of frustration due to the lack of accurate information often passed as valid, only to find out later it was wrong or finding a back and forth argument of he said they said.

I started out my frog room using GEII because I had read article after article after numerous posts that it was fine. 

Then after it is too late to fix it, I find threads here warning against GEII. Many tanks ended up stripped and redone costing me a lot of wasted time. Of course better to know before killing any frogs.

Because I try to research before I do something, I see recommendations for Gorilla Glue, and some people saying liquid nails. 

Ok, this time, I decide to try them out to solve the problem that was the start of this thread, an odd property of the plastic trim on the tanks sold by Petsmart. Silicone sealant does not stick to it. 

So I purchased A bottle of gorilla Glue, and a general purpose tube of Liquid Nails for metal, plastics etc. It is a plae tan in color, roughly the appearance of chocolate chip cookie dough, very smooth and thick, easy to work with.

I assembled two tanks, one with each, and waited for results. 

Gorilla Glue sketchy results. It held, but could be broken off fairly easily. Better than silicone sealant, but I wasn't pleased with the results. 

Liquid Nails. Bonded like crazy. I'll mostly likely require explosives to separate the screen I made from the tank rim. 

However, I then found a thread here by accident warning do no ever use Liquid Nails, it's toxic, everything will die, blow up the tank and start over etc. Doom and gloom, end of the world stuff. Liquid Naisl being another product I'd read "I made my fake rock wall for my frog tanks using liquid nails" kind of story.

So does ANYONE have actual explicit knowledge about the safety of using Liquid nails for the purpose of attaching to the tank? No internal construction, no fancy walls, no sticking plants to anything, just attaching a metal framed screen to the top of the tanks. 

thanks.


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## prolawn_care (Dec 26, 2009)

How long did you let the gorilla glue set for? I have yet to have issues with gorilla glue, always a tough hold!


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## Imperial_Aquatics (Aug 27, 2009)

prolawn_care said:


> How long did you let the gorilla glue set for? I have yet to have issues with gorilla glue, always a tough hold!


it sat for 48 hours before I tried to move it. I wanted to see how much stress it would take after all the problems getting stuff to stick to the frame.

It held better, but it still separated clean away from the plastic frame.


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## pl259 (Feb 27, 2006)

I use 3/16" thick acrylic and solvent weld it into the groove in the rim, using Weld-On 16. After it dries I apply an additional fillet of adhesive on the outside. Never a problem.


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## jeeperrs (Jan 14, 2010)

A picture of where you are applying the glue would help. Silicone never sticks to plastic, which is why acrylic tanks do not use silicone. I would imagine that IF the liquid nails is toxic you could apply a layer of the left over silicone you have as a barrier, since it will stick to the glass and prevent the frogs from touching any glue. I am not an expert by far but I would think that IF the glue is toxic, it is only toxic if eaten or lots of contact. I would neatly apply a silicone barrier so that I could sleep a little more easy, just make sure the silicone is touching the glass. This should stay since the weight is being held by the glue and not the bond of silicone between glass and plastic.


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## Ed (Sep 19, 2004)

If I remember correctly liquid nails is basically a vinyl acetate in a ethanol (I think) solvent that on drying should result in a solid vinly polymer. During drying it should offgas formaldehyde which would be toxic (and is a known carcinogen). If I remember correctly, it isn't stable when in contact with moisture or water (high humidity enviroments may also be risky). 

As for toxicity, when it is totally dry and completed off gassing it should be pretty safe but in the long run may not be quite the stability you want. 

I would suggest using the weldbond as suggested by Eric. 

Ed 

PS: make sure you are using nitrile gloves when working with gorilla glue as that stuff is very effective at initiating allergic responses to various allergens.


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## pl259 (Feb 27, 2006)

Ed,
I think you mean Weld On. There is an adhesive called Weldbond but it's not the same thing.

This is what most people use for bonding acrylic...

Acrylic Adhesives and Cements | IPS Corporation

The #16 stuff is available in a small tube, is thicker and doesn't run like some of the others.

It won't warp when bonded in. I then use 3/16" glass for the door.


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## Ed (Sep 19, 2004)

pl259 said:


> Ed,
> I think you mean Weld On. There is an adhesive called Weldbond but it's not the same thing.
> 
> This is what most people use for bonding acrylic...
> ...


Thanks for the correction. That's what I get for trying to type and have a conversation at the same time. 

I stand corrected. 

Ed


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## jeeperrs (Jan 14, 2010)

I think the last two posts are the best if you can start over. That is the proper way to adhere plastic. PL259 is correct on the thicker Weld On. The rest is very runny and tends to make a mess. 

Just don't blow your tanks up ha-ha


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