CA Glue ?

[Paul Gilbert]

I often use Windex as a stop gap accelerator. It contains ammonia in a alcohol solvent. I assume that it also contains some water. That's all you need, the hydroxide radical and some water.

[robert baccus]

Dave, the lack of oxygen is the set up thing for CA. This is the reasoning for some guys to leave the tops open. The only condition that seems to degrade CA for me is high temperatures. Try two fingers tapped together very quickly with a small drop of thin CA.---with acetone handy of course.

[David Gilbert]

Dave, the lack of oxygen is the set up thing for CA.

Sorry Robert but the chemistry doesn't work this way. The presence of water in your fingers is what activates the CA. If you put a drop of CA on your finger it will harden even though there is oxygen around it. If I still had a lab to play (work) in it would be easy to show that CA will cure with or without oxygen. It's the water or base that causes CA glue to set up and oxygen has nothing to do with it.

Cheers,
David

[John Coloccia]

If it cured due to lack of oxygen, the glue would instantly harden from the bottom up and you'd end up with a large bottle of hard plastic with a thin film of liquid glue on top.

[robert baccus]

Sorry Dave But after some heavy research CA apparently does not set up in wet air but must be pressed tightly to expel air. Some how the water in this air condenses causeing it to catalyze. Hard to wrap my head around this but I know CA on a wood surface will not harden until it is pressed against another surface. Many truths are not readily apparent??? This was a really fun thread Tim. Did some testing using new sriring sticks. Dampened with a rag , glued and clamped 5 minutes--easily broken. The same with dry sticks ect. and the wood broke first. ????

[Tim Boger]

I'll tell you one thing Robert ... I have learned far more about CA glue than I would have imagined !

What an amazing resource this group is.

[John Coloccia]

If you leave a glob of ca in the open, it will skin over and eventually cure if it's not too thick. In other words, the part exposed to the most oxygen cures first. While lack of oxygen may be a helpful condition, reread my earlier post. Research manufacturer websites and they will tell you that generally moisture triggers cure.

[John Coloccia]

That last post was from my phone. I took a second when I got home and simply looked it up:

http://en.wikipedia.org/wiki/Cyanoacrylate

The word "oxygen" is not mentioned once, FWIW. I know there are websites that say you need to squeeze out the oxygen. I don't know where they got that from. I don't want to be argumentative, but I do want the correct information to be out there.

[robert baccus]

I read the same thing John and cannot explain this. But I never put anything on SMC unless I have done it many times. I actually went outside last night and repeated the above experiment twice????? I have also read the oxygen thing in the past but could not locate it last night. I found out one thing---never CA your self to anything you can't drag away.

[Dan Hintz]

Try two fingers tapped together very quickly with a small drop of thin CA.---with acetone handy of course.

Hard to wrap my head around this but I know CA on a wood surface will not harden until it is pressed against another surface.

I actually went outside last night and repeated the above experiment twice?????

Robert,

I think you're making conclusions based upon an incomplete understanding of your experiment's parameters. When you press your fingers (or wood slats) together, you're making the surface area (the part that can accept moisture) extremely large compared to the drop resting on the surface. As such, the reaction is able to move from one surface to the other in a very short period of time. It's not about the lack of oxygen between your fingers (which I assure you still exists).

For another experiment, take two mixer sticks and separate them by a few sheets of paper on either side. Place a drop of CA in the middle of one stick and rest the other on top. The paper ensures there's a gap between them and air can flow. Give them a few minutes and the will be stuck to each other.

[David C. Roseman]

I bought too many bottles of medium CA over two years ago, so I've stored it in the freezer, rather than the fridge. Don't know how much difference the lower temperature makes, but bottles I pull out now seem fresh as new.

David

[robert baccus]

Well you are probably right but my damp sticks with a drop of glue and clamped never did harden in 15 minutes.. Could it be that a tiny bit of moisture (in the air) is necessary but more interferes with hardening? The perfectly dry sticks adhered immediately with one drop of CA. I have great luck glueing up green sappy blanks to dry GB's but it's slow. I need an aspirin.. I'm calling Madame Ledouche--this is witchcraft.

[robert baccus]

My recall of oxygen was in error. Talked to the factory and moisture is necessary but excess will make a joint weak or not set up. I guess wiping with a damp rag was too much. Here in the South humidity is always high which is obviously enough--desert climates often require dampening the wood the man says. A dry day here is 80% humidity. The oxygen thing applies to thread lock---my bad.

[John Coloccia]

The oxygen thing applies to thread lock---my bad.

That's interesting. I didn't know that. Did they mention anything else about it? It can't just be lack of oxygen or the stuff would immediately harden in the bottle. Maybe it interacts with the metal somehow too? Inquiring minds want to know!

edit:
I was curious...I wouldn't sleep tonight until I figured this out.

http://www.henkelna.com/us/content_d...king_Guide.pdf

Interesting read. Somewhere in small print, it says that Loctite cures in absence of oxygen AND the presence of metal ions. Apparently, there's also a primer for inactive metals.

[Jeff Nicol]

I use just plain acetone, but it has to be in a spray mist bottle as the fine mist is what I believe sets off the curing reaction. Like has been said if you just use it in a liquid form it will break it down. I did see a video somewhere on line where a guy was using a spray can of air freshener that worked well so that leads me to believe it is the small mist particles that work best.

I have some bottles of CA that are a couple years old that just sit in the shop with no lids, but the thing that I do is to make the smallest hole in the protective film on the the bottle as this will not let much if any moisture that is in the air get in. I use a sharpened piece of .030 welding wire to poke the first hole and make sure to suck the remaining glue in the tip back into the bottle at the end of the day by squeezing a little air out and then letting the bottle suction the glue back in.

Good luck,

Jeff