Adhering Acrylic To Glass

[NewFishGuy]

So I purchased my acrylic overflow yesterday, was going to install it last night, but I'm concerned about the bond I'll get. I've read that silicone won't adhere as well to acrylic as it does to glass. Anyone have experience with this process?

 

[dale]

the silicone will stick to the glass and wont move so corner overflows are a bit more stable .. it will stick to the acrylic a bit , if you can silicone both sides of the acrylic to the glass it would give you the best bond..

 

[dale]

put the silicone on the edge of the acrylic and press it against the glass and then run your finger up both sides of the joint so the silicone is on 3 sides of the acrylic at the joint..

 

[dale]

of course you will have to do all sides of the box that are touching the glass at once..

 

[NewFishGuy]

That's what I was planning to do. I'd read somewhere on reefcentral that someone used MEK to prepare the acrylic, and it gave a glass to glass type bond.. I've no idea where to find MEK around here lol

 

[TORX]

Just silicone will work fine for that application. Water pressure will push the overflow against the glass. I would not trust it if the pressure was the other way around though. I personally use scs1200 construction silicone and installed my overflow with it. It is the best out there in my opinion. Ryan Nash even just used it for his 700 gallon build.

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[NewFishGuy]

Perfect, that's what I picked up yesterday from the tropical fish room. Black, to match my glass and acrylic. Hopefully I'll get some time tomorrow to get it siliconed in!

 

[AdInfinitum]

Some other silicone products bond more effectively to acrylic but the scs 1200 will be alright. The Methyl Ethyl Ketone mostly would slightly rough but mostly thoroughly clean the acrylic. As an "oily" polymer it attracts and bonds to oils readily and is difficult to strip clean. If you can't find any (it's a pretty common solvent) GE does sell primers to improve adhesion between silicone and difficult surfaces. Where 100% silicone is 100% silicone...there are differences in the carriers that affect adhesion properties. The silicone product that GE sells to use with plastic sheets effectively has some of the primer material blended in that cleans the surface and flashes off as the silicone cures. A good cleaning with a zero residue solvent would help if you can't find MEK or a suitable GE primer. I don't have personal experience with the current silicone blends but I know of that some types will peel right off Acrylic and some really bite in and are nearly impossible to remove.

 

[Matt1997]

No need for any high tensile strength silicone. The overflow will be experiencing almost no net pressure. The silicone is mostly a gasket in this situation. The water inside the overflow will be pushing outwards almost equal to what the tank volume is pushing. A little less due to water loss. Silicone and acrylic have a fairly strong bond. It’s not nearly as weak as most believe. You won’t build a tank doing it but for baffles and overflows its strong. Try ripping an acrylic overflow off of a tank. No way of doing it without a set of razors and wedging the gap. I would just go to home hardware and buy their aquarium safe silicone. 3 tubes I believe $9. It’s their own brand, blue label says aquarium safe. I use that on all small builds. Sumps, and tanks under 75 gallons. After that scs1200 is what you want. My 750 glass was made with scs1200. Around 6 tubes.