Glueing acrylic that has polished edges?

[Mike Null]

It does evaporate rapidly and is a carcinogenic if I'm not mistaken. In any event, don't breathe the fumes.

I use a syringe for application and if you spill a drop you can clean it quickly with dna on a rag or polish it with Novus.

[Dee Gallo]

Dee,
Weldon #16 in the red tube is a thicker version of #3. IMO it is more difficult to work with than #3. It is gooey and sets up very fast making it messy. Weldon #3 is water thin. It works via capillary action, when applied to two pieces of acrylic, it flows between the parts and actually "welds" the parts together by dissolving the acrylic and as it evaporates it hardens and creates the bond. I apply it using a very small artist brush or a syringe. One has to be very careful not to let any drip on to the wrong place. It actually requires very little to get a bond, but the parts have to be dead flush to each other. Rodney says don't use for a T joint and he is right. Best way to do a T if possible, is to cut a slot, drop in the piece, then cement it with #3. That works fine.
I have not tried super glue. It is very expensive. A pint can of Weldon #3 will last a long long time,haven't bought any lately but seems like it is about $16.

Thanks for that explanation, Larry. It explains a lot of my problems and what I can do to make things go smoother in the future. I was under the impression that #16 would help with any tiny imperfect fit issues, but apparently I didn't know that pressing them would negate that. I love it when I learn something new!

So when making a shallow tray shape, what do you guys recommend? I can't make a slot and still have the sides flush. I've been making the bottom sit inside the sides so there is less pressure on the sides and the joint doesn't show as much, but then the bottom takes all the weight. Perhaps I should try some kind of lap joint?

thanks, dee

[Rodne Gold]

Annealing is really only an option if you HAVE to do it , like for military or construction type acrylics - worst of all if you do anneal after machining is that the material "relaxes" and dimensions can be out - so it might have to be re-machined and then annealed again , eventually you might end up with a 20" x 20" item becoming a grain of sand
Crazing many months after manufacturing is normally caused by the user of the item , lets say you have bent a tent shape for a desk name plate etc which requires NO glueing , the bend is really stressed and retains that stress , maybe someone cleans it with something that has a solvent or some other chemical the streesed pex doesnt like , or even perhaps cleans something NEAR it with a solvent , the solvent fumes etc can make it crack at the bend. The problem is that cast acrylic , which is the most stress crack resistant , is more expensive than extruded , which in itself isnt a huge problem , BUT the issue with cast is that a sheet can vary up to + and - 10-20% thickness due to the way it's made (is worse with big sheets cos the glass pieces its cast between tend to either bow or bulge in the centre) so in terms of precise fabrication , the extruded is much better to work with as its pretty much the same flatness - and of course cheaper - and of course more prone to stress cracking.. it's a kinda lose - lose situation.
The thick tensol we work with for uberstrong bonds takes a long time to set - you need to make holding jigs and leave items there for an hour or 2 before handling it - it's irritating. We use methylene chloride for capilliary type bonds. I Also use superglue for "unseen" bonds (hidden so you dont have issues with superglue "whitening" etc - PS the secret of using superglue is that it reacts with moisture - so when doing a superglue bond , you get a much quicker set and stronger bond if you breathe on the 2 pieces before sticking em together)

[Larry Bratton]

"you get a much quicker set and stronger bond if you breathe on the 2 pieces before sticking em together"
What happens if I have ALCOHOL on my breath?????

[Robert Walters]

It does evaporate rapidly and is a carcinogenic if I'm not mistaken.

Mike, you are correct.
IPS Weld-on #3 is a carcinogenic (cancer causing).

It contains METHYLENE CHLORIDE (aka Dichloromethane)
CAS: 75-09-2
MSDS: http://www.jtbaker.com/msds/englishhtml/m4420.htm

I've used MEK in the past, it's available at the hardware store by the pint/gallon, and is not a carcinogenic.
METHYL ETHYL KETONE (aka MEK, Butanone)
CAS: 78-93-3
MSDS: http://www.jtbaker.com/msds/englishhtml/m4628.htm



If you over-apply the solvent, don't touch/rub it. Just let it evaporate is usually what I do.


FWIW...
In the US, almost all chemicals *MUST* have a MSDS (Material Safety Data Sheet) available.
The MSDS will usually list the primary active ingredients and have the CAS numbers listed.

The CAS number is a registry of compounds, so even if it goes by different names, you can easily look up the CAS number and get any details.

[Larry Bratton]

Will MEK work as well as the Weldon?