CA Glue

Excerpts from The Messageboards

Wally Dickerman: What would woodturners do without CA (cyanoacrylate) glue. Here are a few characteristics of CA:

CA glue has a shelf life of about three to six months at room temps after opening. Refrigerating it after opening isn't recommended. Once it starts to thicken, it's best to discard it.
Refrigerating, to store CA glue before opening, is recommended. Do not freeze it.
CA glue bonds well with wet wood.
CA glue doesn't work well with oily wood. Some turners use acetone to remove some of the oil.
Don't use CA glue or accelerator if it's cold. Less than 50° and it doesn't bond well.
When opening a new bottle of CA, throw away the cap. You'll get fewer plugged spouts without it. When I do get a plugged one, I replace it with a used one, and put the plugged spout in a glass jar containing acetone, which dissolves the glue. Save the spout for future use.
If you're getting a white residue, it's because you're using too much accelerator, and too soon. A light spritz will do after 30 seconds or so.

There have been questions about its longevity—or lack of it. However, I've been using CA glue in woodturning for well over 20 years and have seen no evidence of problems.

Bob Hackett: I have heard the same facts regarding longevity and have yet to see them supported by experience. I have made pieces, and own pieces made by others, that are still intact after 10+ years of humid summers followed by wood heated winters with no failure. The only failures I've seen have been the result of impact. I also know folks who build radio controlled planes with CA that are still flying after 20 years. I wonder when the sky is actually planning to fall here.

Russ Fairfield: Yes, I have had and seen problems with repairs that were made with CA glue, but…I have also had and seen similar problems with repairs made with other adhesives. I can't say that CA had more problems, only different ones and to a different degree.

Yes, I have seen the CA separate from the wood. This has been a problem in galleries because they are typically a lower humidity than my shop or home. CA glue shrinks slightly with age and lowered humidity. Add that to the wood shrinkage that is also taking place with the lower humidity, and you can have separation.

But, I have seen the same problems with an epoxy, although to a lesser degree because it can be more plastic and allow for more wood movement. The wood species is a factor because some wood shrinks more than others.

I have seen CA glue that turned a very dark orange with age. I suspect that the cause was contact with salad oils and water, and epoxy repairs did the same thing in the same use.

And, I have had CA lose its bond with oily woods. Olive wood has been a problem for me because I have used a lot of it for larger bowls. Epoxy is a better adhesive for an oily wood.

And I have had the CA repair shrink to below the surface of the wood. Or was it that the wood expanded to above the level of the more rigid CA glue? And, I have had this same thing happen with other materials used for repairs and fillers.

I have adopted a repair philosophy where I never use CA glue to fill a crack larger than 1/16" wide and never without a filler material. Larger repairs are made with epoxies and fillers because of their greater plasticity that allows for more movement with the wood. Even an epoxy has its limits, and can separate from the wood.

I have used enough different CA glues over the years that I have noticed a difference in the incidence of problems with different brands of CA glue. Is it a difference in the formulation or purity?? Or is it just personal preference.

The most common problem with using CA glues is the ugly stain around the repair area from the glue wicking into the surrounding wood. This is something that can be minimized, if not eliminated, but too few woodturners take the time to do anything about it.

As John says below, the first line of defense is sealing the wood with a thinned lacquer, or the same sealer or finish that you will be using on the wood.

Some other things that will reduce wicking of the glue into the surrounding wood are:

CA glue may be fast, but there is no guarantee that it is the universal glue for everything we do. The most obvious solution is to not use CA glue to repair a light colored wood. There are still places where there might be better choices.
A mixture of white or yellow glue and sawdust can still be the best way to make a repair. I have not had a wicking problem with an epoxy. Both require drying time, but that is a small price for a better repair.
Use the CA glue sparingly. Use only the amount of glue necessary to do the job. Do not flood the entire area with glue.
Use one of the thicker, slower curing, CA glues. The medium glues are less likely to wick into the wood as much as the faster thin glues.
Always allow for sanding or making a light finish cut after making the repair. Wicking of the glue tends to be a surface problem. 1/16" will usually remove all traces of it.
Always use a filler material. Besides adding substance to the repair, it will absorb excess CA glue instead of the wood.
Mix the filler and the glue on the surface and trowel it into the void. That keeps the excess glue out of the hole. Mixing everything inside the void doesn't.

Les Robison: I first used a CA glue in 1958. We used it to glue mica chips into X Band Microwave STALO's for the original orbital space shots before manned flight. It was and is called Eastman 910. If you do a Google search for Eastman 910 you will find that the manufacturer says six-nine months after opening the container. However, I feel this is the same as some of the dating on items in the grocery store. The manufacturers want to protect themselves from law suits. Also, many of the other items you point out are covered due to the expansion/contraction parameters as well as the temperature factors.

John Lucas: I always put a thin layer of whatever finish I'm going to use on that piece over the repair area. This will be sanded off after the repair along with leveling the CA joint.

Ric Taylor: I have been using all types and all brands of CA glue, in many types of applications and in various climate conditions since 1976. I have never had a glue failure of any kind, I have never seen any evidence of shrinkage, and I have never seen any color change in any of the applications. The joints and fills that I made in 1976 still look as good today as they did on day one. I have had glue block failures after a bad catch, but my comments above refer to the finished pieces.