Adhesives & Solvents & Acrylics

[takitus]

Spent some time today playing with face to face adhesion, and figured I would share my experiences/results with everyone.

I need to adhere clear acrylic to colored acrylic and have as little visible mess as possible. A while back I purchased some SCIGRIP Acrylic adhesive, so I figured this would be a great chance to test it out.

Quick note, this stuff is incredibly TOXIC, so wear as much protection as possible and keep your area very well ventilated.

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Application

So I tried each type of glue with a small piece of acrylic.
The right 2 were the SCIGRIP #3, and #4. I used the capillary method for those, by placing the acrylic down and running the needle of the applicator along the edge. I ran it past a few times to see if I could get full coverage. It didnt happen.

I then attempted to make a puddle using #4 (its slower to eat the acrylic), and place the piece on it, and then go along the edges to have everything filled in.

All of these left bubbles and air pockets inside which just isnt going to work for me. They do bond really well though

The two on the left were gel CA and liquid CA. Those worked so much better here, but are difficult to keep from moving and can be messy in their own way. I will probably be using these for the large connections.

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Cleanup

Glueing two faces together is difficult in that determining how much adhesive to use is close to impossible. Glue will pretty much HAVE to come out the sides if you have to have 100% coverage. This causes problems of its own.

When SCIGRIP is not between two pieces of acrylic it just eats it and leaves a white spot.
CA glue leaves foggy/crumbly mess as well.

Which one is worse? SCIGRIP because it actually eats the acrylic away and its difficult to clean this off. Nothing works to get rid of it except other solvents which sounds troublesome.

CA glue is also a pain to get off as well, but its an additive adhesive, so its not actually doing damage to the material.

The answer here for both of these is acetone. Acetone is also a solvent, albeit a much weaker one. It can remove extra CA as well as help to get rid of white spots left by #3 and #4. (It also pulls sharpie off of acrylic… so my labels went bye-bye lol)

WARNING: Acetone can damage/weaken acrylic and cause crazing/cracking, especially in corners.

In the two photos below, I had applied too much gel glue to the far left piece and it was foggy everywhere. Acetone followed by a quick wipe with a soft eye glass cleaner got rid of almost all of it.

I wanted to see if I could do anything to get rid of the white spots from the SCIGRIP, because im clumsy and know I will spray it on places it doesnt need to be. This is a test piece with two spots for before/after.

I tried rubbing alcohol and zeiss wipes first. Nothing. After that I tried acetone, and after one pass it looked like this:

After the second pass and a wipe with a glasses cleaner it was almost imperceptible!

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Conclusion

So it seems for this application, CA glue is going to do the job much better than SCIGRIP/Weld-On. Any overflow will easily be remedied by acetone.

For butt-end joining however, SCIGRIP works REALLY well. I definitely recommend practicing first and wearing gloves.

I hope this will be useful to some out there. Feel free to leave any questions here for me. Happy glueing!

[cynd11]

Thanks so much for this summary! It’s an area I’ve struggled with so it’s great to see a clear winner. Thanks!

[dklgood]

Thank you for working on this vexing issue. For small things I use the 3m double sided tape applied to one of the pieces before cutting. It works, but the cost is high. I will use your information for future applications.

[raymondking32]

Killer write-up on your findings. I totally forgot about how to cleanup CA glue from acrylic, and literally just remembered that I have some goof-off that I wanted to try. In the case that that fails, It’s good to know acetone works, so thank you for that knowledge!

[jamesdhatch]

Outstanding acetone tip! That one gets added to the toolbag.

[marmak3261]

@cynd11

clear winner

Ha!

And this is why @takitus is one of the immortals of the forum.

[james_mackey]

I literally just came from amazon’s site where I had added some SciGrip to my cart. I had recently done a friction fit acrylic job, and wish I had used a welding product to make it more secure. I had tries CA Glue on one of the initial tests, but decided that because it was back lit and it was a rush job as a gift, that I did not want to have any visible “glue dots” from the back visible on the front.

So I have a question:
If I were to the SciGrip in this application, where the kerf is eliminated and the pieces are bonded edge to edge after being tightly fit together with a tight friction fit, do you think that the needle application process would would well to get it right into the joint? and would the #4 be better then the #3 because of the lower vizibility of the point of application, or would the faster bonding properties of the #3 be better and the acetone clean up worked well enough that the difference was minimal. i’m not sure if that makes sense. I hope it does.

AWESOME (in the true sense of the word) write up! I love your experiments on this, and the timing could not have been better!

[takitus]

Yes. This is where scigrip/weld-on excels.

When joining the thin dimension of a piece to another piece, it works exceptionally well. I’ve also had great luck with superglue, but you’ll get a better bond with weld-on because it actually melts them together.

As for #4 vs #3, I’d go with whichever meets your needs for working time and bonding time. I haven’t noticed any difference in error spots.

[mrinken]

THANK YOU!!! I created an aquarium top for my step-daughters fish tank and the biggest problem with the whole thing was the glue / clean up. CA was my choice, and while it worked well, I had no way to clean up the white mess other than to do my best job wiping as much as I could off.

But THANK you again for such an amazing write up! And completely agree about breathing / eye protection. I’ve started wearing a full respirator in the Wood working shop when cutting things on the table saw (I’ve always worn eye protection) and that same respirator also filters out fumes from glue / solvents / finishes. My kids think I’m weird, but no chemicals in the lungs anymore!

It also works great when cleaning soap scum off of the shower walls / glass doors. Weird to be wearing essentially a gas mask when cleaning your shower, but hey, I can now be in there with those harsh fumes!

[ben1]

Did you try any of the thick acrylic solvent cement? Weld-on makes one, #3 maybe? This may work better for what you need since it can be spread thinly and clamped.

[mnemosyne]

wait, what, acetone does? This changes everything…

[mrinken]

Well, that was written poorly. Wearing the gas mask works great when cleaning off soap scum with the only thing that seems to get it clean (Oxy Clean soap scum cleaner).

[mnemosyne]

thanks - that makes a lot more sense!

[mrinken]

I mean you could TRY acetone on a shower door. I seriously doubt it will work, but hey you never know!

[mnemosyne]

tbh mine probably needs a harsh solvent!

[mpipes]

@ben1

Did you try any of the thick acrylic solvent cement? Weld-on makes one, #3 maybe? This may work better for what you need since it can be spread thinly and clamped.

SciGrip #16 is the thickened stuff. It forms a skin on the surface almost immediately after dispensing so you really don’t want to disturb the pieces afterwards moving them into position. It gums, strings and bubbles.

I use #3 most, and for face to face bonding I flood the first surface then lay the second in place and let the excess solvent flow out. Do it quickly and there won’t be any cloudiness left behind. If you hit a snag putting things together and it takes a few extra seconds to align or remove the work pieces from the puddle of solvent, yes you will have a mess.

Laser cutting acrylic leaves an almost indiscernible raised lip around the edge of the part and that can either stop weld solvents from getting between the parts, or act as a block for air to escape as the joint is filled. You can actually see this happening as you keep dumping solvent into a joint and one air bubble at the opposite end just won’t flow out. Drag an X-acto around the perimeter to take that burr off and things go a little easier.

It does take practice though. I get flawless clear joints with #3 unless I accidentally slide the parts.