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Bonding Acrlyic to Glass?

1155 Views 12 Replies 7 Participants Last post by  ReefkprZ, 
Chafire
2
Curious if anyone has ever bonded acrylic to glass? Here is what I'm trying to do:

Last year I purchased 5 pieces of tempered glass from Staples here's the link: http://www.staples.com/14-x-14-x-3-16-Tempered-Glass-Panels/product_721876?cmArea=SEARCH

I was testing out building my own aquarium measuring 14"x14"x14". I succeeded In doing so:


But with a slight problem, when you build a tank with pieces that measure all the same the corners do not touch on perpendiculars as pictured:


Granted it held water and did so for a couple of hours until I emptied it. But it makes me a bit nervous not having the corners perpendicular with one another. So the tank has just been sitting for the past year. Now I would like to put it to use but wish to not have any filtration tubes coming up and over and would rather drill the bottom for two bulkhead fittings. But this being all tempered glass that idea go's right out the window.

So I've been looking for places around my area to replace the bottom sheet off glass, haven't had to much luck and can only find one place (dullesglassandmirror.com) online that will cost around $35 shipped. So the idea of "what if I used a piece of acrylic for the bottom?" popped into my head and am wondering if this would be an issue. I've read that acrylic expands and contracts more easily than glass so the silicone seal may become weak over time. But if the aquarium is kept at 78F at all times then there wouldn't be much expansion and contraction? would there? The thought of drilling a $10 piece of acrylic and it cracking/breaking doesn't bother me as much as a $35 piece of glass.

Also with this new base it would measure 14"x13-5/8" so the corners would be perpendicular.

So to sum it up would it be fine to bond acrylic and glass together with silicone?[/
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F
I'm no expert but i don't think it will work can't remember why something about expansion rates I think also silicone will not bond very well to acrylic so silicone is out.
try a local glass guy sometimes they will give you small pieces like that free or next to free especially since you could use a scratched piece
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N
Im sure you know but using tempured glass is a little risky, if you tap the edge a little too hard it wont chip but explode into a million pieces.
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bigboij
since you dont trust the other tank you made due to the corner offset try setting it up in the garage or on a patio and let it sit for a few months to see if it ever fails, its not a huge volume of water it may be able to work just fine
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ReefkprZ
the expansion rate is different as well as the bond strength (glass to glass is a 10 on a scale of 1 to 10 acrylic to glass is a 5 on the same scale, the seal is 100% guarunteed to fail under pressure at some point. may last for a while but there is no way I would trust it over anything valuable.

if you want to use acrylic as a bottom pane you'll need a supporting framework to set it in. even then the reliability will be suspect.

look at it this way, if using acrylic as a bottom pane was feasable for a glass sided tank, a ton of companies would do it for the simple fact that its cheaper. and more likley to withstand sudden impact, scratches easier but who cares if its the bottom pane...... its not really that there will be a huge difference in contaction or expansion due to temp changing a lot BUT if you build the tank and bond it at 70 degrees, and then you fill it with water at 75 degrees, the glass expands 1/64th of an inch and the acrylic expands 1/8 of an inch thats a HUGE strain on the silicone bond not counting water pressure. since your starting with a weaker bond of silicone your guaranteed to have a catastrophic failure eventually.


I keep editing this post to add stuff to try and explain what I mean, I'll just sum it up You really don't want to try that. an acrylic bottom pane on a glass tank will lead to a disaster.

OH and you can get a perpendicular mating of the glass panes with all 4 sides measuring the same, you need to pinwheel the panes.
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Chafire
Thanks for the info Reefkprz, Still not sure if I will go with this method. It would be neat to expirement with it just to see how long it lasts although if it did give out I would not wanna deal with the 12G of water. Fooledyas I Have sent a message to a local glass place asking for a quote on a piece of glass explaining that I don't care if its scratched.

So Heres another question If acrylic wouldn't be a good option. What about using a piece of wood measuring 14" x 13-5/8" then waterproof epoxying it just like plywood tanks and siliconing it together with the glass. I don't see this being a huge issue since silicone is used to hold the front pain of glass to plywood tanks. unless it's an issue of how much surface area of the two are touching? Just another Idea, although the cost off waterproof epoxy is probably more expensive than the piece of glass.

I've noticed your post growing over the last hour :D, I never thought of pinwheeling them, that is a great idea!
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mordalphus
on plywood tanks, you don't just rely on silicone to hold the glass to the front, you also rely on water pressure pressing the glass into the wood. If you had a wooden bottom, the pressure would be pressing on the 8 seams instead.

Also, tempered glass is the absolute worse thing you could use on an aquarium. You can buy cut to order glass from a glass shop for a very good price. I make custom tanks, and although I get a good price from my guy, I can buy the glass for a 14 inch cube for 12 dollars.
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Chafire
mordalphus said:
on plywood tanks, you don't just rely on silicone to hold the glass to the front, you also rely on water pressure pressing the glass into the wood. If you had a wooden bottom, the pressure would be pressing on the 8 seams instead.

Also, tempered glass is the absolute worse thing you could use on an aquarium. You can buy cut to order glass from a glass shop for a very good price. I make custom tanks, and although I get a good price from my guy, I can buy the glass for a 14 inch cube for 12 dollars.
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Great information, I totally neglected the thought of the pressure also being benneficial to the seal. I realize tempered glass isn't the best thing, it seemed like a good deal so I compulsively bought it and experimented with it. :icon_eek: 12$ for all 5 pieces thats an awesome deal!
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mordalphus
It's wholesale pricing since I buy quite a bit from them, but you should have no problem finding 14 inch squares for less than 5 dollars each, especially annealed (untempered) glass. Tempered will usually be 1.5 times the price, depending on how large the suppliers kiln is, some have minimum pricing for tempered, and some will pre-drill holes before tempering (but the glass, and the holes will sometimes become distorted or shrunken).

Ordering glass on the internet is always a great way to get a terrible price. Family owned glass shops will always be a friend, and will always be willing to bend the rules to make a sale.

For what you spent on your tempered glass, I would have made and shipped a custom 14 inch cube with 7mm glass and untempered bottom :p (and for another 40 dollars would have acid etched your name or a logo into one of the sides).

But great enthusiasm! If you needed at 13x13 inch piece for your bottom I could have mailed a piece to you! I don't have any 14x14 pieces right now though. And nothing in 3/16ths thickness. I would put calls into local glass places (do not call window places, most only install pre-made cookie cutter windows, and do not know how to cut glass).

You'll have this thing done in no time! And if you remove silicone, remember that silicone doesn't bond as well to silicone as it does to glass, so use acetone or 90% isopropyl alcohol and razor blades to CLEAN the old silicone off the bonding surfaces before you try to re-silicone.

Good luck!
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ReefkprZ
mordalphus said:
You'll have this thing done in no time! And if you remove silicone, remember that silicone doesn't bond as well to silicone as it does to glass, so use acetone or 90% isopropyl alcohol and razor blades to CLEAN the old silicone off the bonding surfaces before you try to re-silicone.

Good luck!
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that's probably the most important step most people skip when resealing tanks that leads to seal failure down the road. great advice there :proud:
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H
Pinwheeling the 4 sides doesn't help much, because the bottom will still be a different size from the sides.
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Chafire
Got a quote back from one of the glass companies I contacted. I was quoted $8.75 for each piece at 3/16" being $43.75 which is still not all that bad. And $12 per hole but they do not have the correct bit size I want. I'll wait to hear back from some of the other places.
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ReefkprZ
Hoppy said:
Pinwheeling the 4 sides doesn't help much, because the bottom will still be a different size from the sides.
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well, it helps in the fact that the sides will line up perpendicular when they are all the same size, but your right about the bottom I forgot to mention that, my bad. (gonna blame it on the beer)
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