View Full Version : How to Glue(or weld) acrylic together?

12/05/2007, 02:08 PM
Ok, I have my acrylic and now just need to bond it together. I looked on the internet for advice on how to bond this together with weld on #4 and found 2 different methods. On youtube tap plastics has a video where they place both parts of the acrylic together and using a needle applicator place a bead of weld on along the seam. On Melevsreef he puts guitar strings between the joint and then applies the weld on. I like the tap method because its looks easier, but will it work. Please help me understand this. Thanks

12/05/2007, 02:15 PM
Either way works. That weld on 4 will squeeze right between the pieces in need of bonding...it's like water. What ever way you choose, as long as you apply an even dose all around, it's not going to leak.

12/05/2007, 02:19 PM
I have built a 25gal tank and two sumps about 30gal apiece using weld on 4. The needle applicator is a must. I practiced on some scrap that I picked up for a few bucks. Once you've done it a couple time it's not so difficult. Havn't tried anything big though. That's a different story.

12/05/2007, 02:24 PM
Oh yeah, tried the guitar strings. Way to difficult. The weld on 4 is actually more viscous(runny)than water. So it wicks into the seem no problem. Just make sure your cuts are as clean as you can get them.

12/05/2007, 02:34 PM
Good, the easy way works well. Thanks for the help everyone.

12/05/2007, 06:34 PM
The purpose of the guitar strings or whatever spacer you might try to use is to separate the two pieces so you can get a good even layer of solvent in between the parts. Then, the separation also allows the solvent to melt a small portion of each of the adjoining surfaces. So, when you drop the two surfaces together by removing the pins (guitar strings), the two softened surfaces actually squish together and become a single welded piece when the joint dries.

If you just set one part on top of another you will have a much harder time getting enough solvent into the joint to melt the pieces together uniformly. I would never use this method on a tank that I expected to hold water. I have used it for quick joinery and tacking acrylic pieces together that weren't being used in pressure applications, and it works fine in those instance (although still not as uniform, bubbles in the joint seem much more common).

If you set up your workpieces correctly with the proper equipment (90s, clamps, good flat surface), I really think you will find that "the pins method" is not that difficult. See this link on the proper method: http://www.reefcentral.com/forums/showthread.php?threadid=390652