|Posted on Wednesday, June 15, 2016 - 11:38 am: ||
Kind of off topic, but probably handy if it works.
I'm playing with solvent welding of plastic. So far it looks pretty promising as a tool to have in the tool box.
In it's simplest form, solvent welding is what you do when you assemble plubming from PVC pipe and fittings. The Oatey primer and glue you use is mainly an aggressive solvent, and when you use it to join things, you are really welding the plastic, not gluing it.
(When you weld, you are joining two items of the same material using their native material. When you glue or braze, you are using another material as an adhesive to join things.)
If you have ever used PVC, you know how fast, how hard, and how crazy strong that weld is.
That Oatey stuff also joins/welds ABS plastic (another type of plastic similar to PVC). You can get ABS plastic in lots of different forms, it is tough, forms nicely with the application of heat, and is very tough stuff. I get sheets in varying thicknesses at a local place (that is actually a big mail order place) called Parts Express in Dayton Ohio. Car stereo installers like the stuff to solve all sorts of problems.
The first experiments with the ABS and Oatey welding look great. Strong as stink, easy to work with.
I'm not trying another experiment I heard about... basically, you grind or cut up ABS plastic into little pieces, soak them in acetone, and you end up with an ABS paste of any consistency you want (add more acetone or add more ABS). You can then use that like a filling material, or as a glue. I have a jar out soaking now, and in just a few hours it is already a lovely little pourable fluid. In theory, when you put it somewhere, the acetone evaporates out over a week or so, and its just ABS again.
I'm trying to repair a large (and pretty expensive) ABS panel for a Winnebago RV that I borrowed and broke. I don't know if it will work for this or not, I've been looking for an excuse to play with this stuff for a while, so now I have one.
It also looks really interesting as a conformal coating for electronics projects. I'll probably play with that as well. It looks really good for repairs as well.
I'm assuming it won't be great for fabrication, as I assume if you cast it in a lost foam or sand cast, it would shrink by the proportion of acetone while it cures, so that is no good. But you could probably use it as a decent filler if you applied multiple coats and let it dry in between to build it up.
Any actual chemists want to weigh in on what is actually happening here, and if a paste made from acetone ends up just plain ABS again after the acetone evaporates? Or is it some new better or worse substance?
Thanks in advance for any knowledge or experience here...
|Posted on Tuesday, August 13, 2019 - 01:49 pm: ||
Just found this thread and I'm wondering how the experimenting turned out, Reepicheep? Or are you still high from breathing all that acetone?
|Posted on Tuesday, August 13, 2019 - 06:24 pm: ||
Use methyl ethyl ketone. Acetone decomposes plastics and does not weld well.
|Posted on Wednesday, August 14, 2019 - 11:19 am: ||
The problem with MEK is it is a known carcinogen and way bad for you.
Don't get me wrong I use it all the time (Weld-On #3) as a solvent for welding Acrylic, Polycarbonate, PVC, and PETG. But I use the solvent by punching a very small hole in the seal under the cap. Then I use a glass syringe, and a # 21 needle to inject it into the joint, using the capillary action of the solvent. When done I return the unused solvent back to the can with the syringe. Using this method, only the amount of solvent needed for the bond is used, and minimizes the inhalation exposure risk. Using a syringe to never touch the stuff also minimizes exposure from absorbtion through skin contact.
The slurry idea is an interesting one but Toluene might be a better choice for ABS. It's still bad, and still dangerous, but at least it isn't proven to give you cancer down the road. 1,2 Di-chloroethane is another plastic welding solvent, and is a "possible" carcinogen, (as opposed to the "known" MEK risk), but definitely harder on your system than Toluene.
Disclaimer: I am neither a doctor, or chemist. My advice is opinion based solely on work experience, and employee MSDS training. As such, it is worth exactly what you paid for it.
(I'm not that fat, it's just all the toxins in my liver)
|Posted on Sunday, May 17, 2020 - 10:54 am: ||
I've found that Oatey "Medium black ABS cement" #30999 works really well on M2 plastic body panels. Specifically cracked seat fairings. You have to store the cans in a temp controlled space upside down so that they don't dry out and maybe you'll get a second use out of the can.