LocTite CA

[Whaler]

I had a need today for some thick CA and had a bottle of LocTite thick gel so I tried it. I let the blank set for about 30 min before putting it on the lathe. As soon as I started slipping it on the mandrel I was able to push the tube out. I'm glad that I had bought the smallest bottle they had.

[DUD]

Dick

Thanks for the heads up. I haven't tried any and now I won't. Bill

[Joe DeFazio]

Hi Whaler,

I haven't used LocTite brand gel CA, but I have used large quantities of another brand of gel CA (FastCap). The gel CA I have used does not set up at all unless you hit it with CA accelerator spray.

All of the other viscosities of CA (thin, medium, and thick) will set up via exposure to moisture either in the air or in the wood product that you are gluing (or on/in your skin - be careful! I've had to slice my fingers apart with a razor blade when they were glued together far from home / far from a debonder or acetone).

As I was preparing to teach a class on glues, I did an experiment on the curing properties of gel CA (FastCap brand, once again). I left out a sample smeared on a piece of cardboard for 24 hours, exposed to the air and to any moisture in the cardboard. It did not even begin to set up after a day!

I suspect that additives are mixed into the gel CA so that it does not cure in the bottle. If you leave thin CA in a bottle that has been opened for many months, it begins to thicken (if it doesn't harden completely). Similarly, medium will get a little thicker. I am speculating (and speculating only) that if additives weren't added to gel CA, it would harden too easily to be useful as a commercial product that was destined to sit on a store shelf (or a customer's shop shelf) for perhaps a relatively long time before use.

So, I am recommending using an accelerator (or "kicker") with gel CA. You can smear the CA on one piece, spray the other piece with accelerator, and then assemble them. The accelerator should hasten curing within a short period of time (seconds/minutes). If you're having trouble spraying CA accelerator into a small area such as a pen tube, dip a pipe cleaner (Chenille) into the accelerator and use the pipe cleaner to apply the accelerator.

It has been my experience that any brand of CA accelerator will work with any brand of CA glue. Some accelerators work faster/hotter than others.

Joe

[Whaler]

Thanks for the info Joe. It was the first time I had used thick CA so It could have been my fault rather than LocTite's.

[rjwaldren]

Just on personal experience - I've tried 2 different "locktite" adhesives - Their construction adhesive and a household adhesive and I've been disappointed. I personally won't buy their products anymore, with the exception of thread lockers.

[cgallery]

I haven't used LocTite brand gel CA, but I have used large quantities of another brand of gel CA (FastCap). The gel CA I have used does not set up at all unless you hit it with CA accelerator spray.

Hi Joe. I've used the Loctite Gel on plastic components and it has worked quite well. Is there something in the plastic that speeds curing?

[Tom Slick]

It may have been a function of the gel type rather than anything else. CA cures in the presense of moisture, that's why it bonds your fingers together so quickly. Certain CAs will not cure for quite awhile if they are exposed only to air, accelerator will take care of that. I use FastCap jel for trimwork and even when the joint is held together it doesn't set for 30-45 seconds. using a little accelerator on one piece makes it fully cure in 20-30 seconds. If you are using it for finishing the accelerator may make it cloudy. It might be worth it to mist water on the CA once it is applied just to see what happens.

[Uncle Cracker]

Is there something in the plastic that speeds curing?

I thought just the opposite. I've put CA of all thicknesses on plastic bags (left over from pen kits) to apply directly, or with toothpicks, and have seen even the thinnest take hours to set up. Wish it was the same for fingers...

[Slik Geek]

Loctite is a respected leader in adhesive technologies - a large number of companies world-wide depend upon their products. If somebody has poor performance with their products, I submit that the product was either beyond its expiration date or it wasn't used properly.

(Note that I don't knowingly have any ownership of Loctite, its parent company, nor do I have anything to gain by defending or promoting their products. I have just used their products in a professional environment as a customer).

One of the big problems with cyanoacrylates (super glue) is that most people don't understand how they work, or have a misunderstanding about how they work. A big problem has been the marketing of super glue. Often the promotional materials / product labeling for these adhesives are not very helpful and give false impressions.

Super glue stays liquid because a weak acid was added to the adhesive by the manufacturer. This acid acts as a stabilizer. In order to cure, a weak base (alkaline) surface is necessary. The moisture on the surface of a person's skin meets this requirement very well, hence the rapid bonding of skin one experiences when a bit of super glue ends up on the fingertips.

Super glue doesn't "dry" (give off moisture) in order to cure. Curing is the result of a chain reaction, which forms a thermoplastic resin when the proper conditions are present. If your super glue doesn't cure within tens of seconds, the conditions are not proper for its use.

The proper conditions (without an accelerator, with classic runny cyanoacrylates) are when the adhesive is:

confined between two surfaces (a narrow gap, like 1/10 of an inch / 0.3 mm)
in the presence of microscopic surface moisture (which provides a mildly alkaline condition)

Oily surfaces will prevent proper adhesion. Note that wetting the surfaces with water will likely add too much moisture, (remember it needs microscopic surface moisture) resulting in a failure to properly cure.

With additives, super glues have been created that can fill thicker gaps. Accelerators also have been produced to allow a rapid cure in a low humidity environment or on acidic surfaces.

The bottom line is that super glues are more complex than most people realize, resulting in inconsistent results.

For consistent success on woods, I suspect that you MUST use an accelerator. (I'm not sure on this, but I think most woods are slightly acidic, which will prevent super glue from curing properly).

A formulation specifically intended for wood is probably a good idea, as the adhesive will have been engineered for the specific challenges that wood presents. I'm guessing that most, if not all cyanoacrylates intended for wood will have a more gel-like consistency to allow filling of the thicker gaps that wood will have. But just because the super glue is thick, doesn't mean that it will work well with wood.

Plastics present their own challenges for super glue, resulting in poor or inconsistent results there as well. When the conditions are right, you can't beat the speed and convenience of super glues. But when the conditions are wrong, the result is usually frustration and stuck finger tips.

[pierhogunn]

Slik...

wow, that's a great explaination, and I believe it deserves to be rolled into it's own thread, made sticky, or stored up somewhere in the reference section of the site..