Attaching Acrylic to Glass

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PEPSI

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I have an extra 20 gallon tank and pieces of acrylic hanging around and i was thinking about putting together a sump/fuge. My question is, is it possible to attach acrylic to glass? If so, what can i use that will be reef safe? I've checked out all the other DIY projects and they've all been acrylic/acrylic or glass/glass. I haven't seen a glass/acrylic hybrid system yet.

I tried doing a search but that function never works!

Thanks for any input

Andrew
 
i was reading in other threads and post that silicone doesn't stick to acrylic as well as glass so i will have a problem bonding the two. is this true?


Andrew
 
You need to embed the acrylic in a bead if silicone. In other words there has to be a bead on both sides to hold the acrylic in place. You can rough the edges if the acrylic up a bit to help the silicone get a better grip.

In all honesty window glass is very cheap at the hardware store. Have them cut a few pieces for you. It is easier to work with and will cost you less than $10.
 
Silicon attaches to acrylic fine. It just doesnt Bond. Use atleast 1/4" acrylic, or its just going to bend on you, and pull away from the seams, and then you'll have issues.

Window glass is really thin.
 
I have used aquarium silicon for years in sumps. It has never come lose--if it does it would only leak into the sump. I would bled to death if I used glass baffles in my sump. Acrylic is safer. R
 
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Window glass is thin, but then again we are talking about baffles in a 20L... plenty thick enough for that... You can get it in 1/8 or 3/16 if memory serves me. All of my overflows are 3/16 as far as I remember.
 
I used aquarium silicone to do the baffles for my refuge. It works ok. It could be better, but it is just a refugium. It should last a few years, and by then I'll upgrade anyways.
 
Thanks for all the great responses! i'll try my luck with the acrylic for now, this is only a temporary set up so i'll learn from this.
 
For my overflow I used epoxy on the edges and then sealed with a bead of silicone on the edges inside and out. Doesn't leak and isn't going anywhere. Only problem I see with silicone is for pressure applications, where the weight of the water is pushing against your seam.
 
I have silicone holding my acrylic top brace to my glass 180. It's works fine! I'd like to see some proof that Silicone actually does ANY sort of chemical BONDing to glass. I think it's all mechanical bonding just a matter of how well the surface is prepared.
 
Hrmm it may help you to think about what glass is made out of and what "SILICone" is made of. You then may want to ponder why these two items would form such a good bond and why the silicone may not form a good bond with other surfaces.

Who said it was a chemical bond?

Silicone does not form a strong bond with acrylic. You can rough it up to form areas for the adhesive to grip, but the bond is still very weak because the surface does not form a good grip at a molecular level.

Your top brace may not have much pressure on it, but you sure did take a risk using silicone to bond acrylic.

Other examples of similar situations: Polyurethane does not stick to PVC at all, but will stick to other plastics to the point of being almost impossible to remove. "saran wrap" sticks to some plastics and not others.

Bean
 
It's made of Silica ( slica is also found is sand, an abrasive). Silicone per manufacturers suggestions is for bonding Smooth surfaces. Think of a suction cup on a good smooth surface even a small suction cup can hold tremendous amounts of pressure. By implying silica between glass and slicone having an a better bond is implying that on a chemical level those two are bonding..which is untrue. The silica molecules in the Glass are NOT chemically changing, moving or aligning with the Silicone adhesive. It's simply the surface prep. Ever wonder why if you take a polished piece of METAL and paint it, it doesn't stick, but if you rough it up a bit with some 600 grit paper you have to chisel it off? Same metal, but different outcomes.... it has to do with mechanical bonding.
You gave some examples of Saran wrap. This "bond" is static and or vaccume based. Saran Wrap also called cling wrap works on creating a vaccume. Polished surfaces work well like glass. This is because it can create a good seal. Surfaces with larger pores can not be sealed as the "cling wrap" can not create a vaccume. It will not stick to some plastics as they are anti-static. It also has a bit of static characteristics as well due to it's size.

I really have NO idea where you got the idea that Polyurethane will not stick to PVC? Alot of PVC manufactures suggest it for bonding rigid and plasticised PVCs?

Ever wonder how Teflon works? The molecules are SO tightly packed that the surface is so smooth there is no roughness for any type of mechanical bond to form. On the same note it's also fairly chemical resistant as well because of the strong carbon bonds in the chains of fluorine.
 
I never said there was a chemical change, this is twice that you have said that. Secondly, I am fully aware of what "silica" is and where it comes from, alas I was the one who mentioned it in the first place. Glass (some glass) is silica based and so is "silicone sealant".

2 textured surface will have better adhesion if the textures match. This simply equates to surface area and can be looked at from a MACRO standpoint (surface prep) but more importantly from a MICRO standpoint (surface structure). Acrylic and glass are different, all the DIY sirface prep in the world does not change that.

I don't ever "wonder why" rough metal holds paint better than polished metal, I know why.

The Saran wrap was a bad exemple and should have been left out, I was trying to illustrate that some materails stick better to others. I am aware that saran wrap relys on static.

Your teflon example illustrates my point. The glass and acrylic have to different surface structures. The silicone has better adhesion to the structure of glass. This is not a "surface prep" issues, it is the surface structure on a molecular level.

Teflon? Yes I know how teflon works. It was my choice as a research project back in the college days.

How did I ever get the notion that polyurethane will not stick to PVC? I have pumped millions of pounds of SINGLE and PLURAL polyurethanes. General polyurethanes don't stick to PVC, it's that simple. Are there polyurethane products used to bond PVC, YUP! There are tons of them, but they are highly modified "glues" not straight diisocyanate-polyol blends. Some of these "glues" form a joint stronger than the PVC itself. Many are designed to alter the surface structure of the PVC (chemical bond) as well as add body to the joint (unlike a water thin solvent).

In any case this has moved way past the scope of the question at hand. The bottom line is that 100% silicone sealant sticks to glass far better than it does acrylic. You can make a "better" acrlyic joint by roughing up the surface, but the adhesion will still not be as good as that to glass. Increasing the surface area of the joint will also help.
 
Bean Obviously we both know about the subject. I guess what I'd like to show is even though it may not be AS strong as a bond with glass, the bond is strong enough however for our application.
 
<a href=showthread.php?s=&postid=6961521#post6961521 target=_blank>Originally posted</a> by BeanAnimal
Window glass is thin, but then again we are talking about baffles in a 20L... plenty thick enough for that... You can get it in 1/8 or 3/16 if memory serves me. All of my overflows are 3/16 as far as I remember.
Click to expand...

Ok. The shady HD near me only has it in 3/32. Thats crazy.
 
<a href=showthread.php?s=&postid=6976874#post6976874 target=_blank>Originally posted</a> by Bug_Power
Bean Obviously we both know about the subject. I guess what I'd like to show is even though it may not be AS strong as a bond with glass, the bond is strong enough however for our application.
Click to expand...

For most sumps and other small DIY projects, I would fully agree. I would not however trust a cross brace such as you have! That said if it works for you then all is well. The important part (as we have both pointed out) is that the acrylic surface must be roughed up to help create a better bonding surface.
 
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