Diagnosing Problems Related to Frozen Glue

Woodworkers discuss what happens when glue freezes in the container. April 10, 2009

Does someone know of ways to test glue to see if it was frozen?

Forum Responses
(Adhesive Forum)
From contributor V:
Let some dry, and if it appears chalky at all, it's been frozen. It usually gets chalky looking at the outer edges of the glue spot/smear/whatever.

From Jeff Pitcher, forum technical advisor:
Most PVA glues are freeze/thaw stable through five cycles. This does not include most cross linking PVA’s. If the glue has been frozen and the emulsion is broken it will look like cottage cheese and you will not be able to stir it and bring it smooth again. If you can stir it and it smoothes out it will work fine. Chalking will only occur if you are trying to use the glue at a temperature below the glue's minimum use temperature. (The wood should also be above temperature). If you have any questions about the glue's temperature issues be sure to contact the manufacturer.

From contributor V:
I'm going to have to disagree with you on that. I have used glue that has been frozen in the drum during shipping. It is chalky, and prone to failure at the glue line. No cottage cheese texture either - not to say that doesn't occur, just not in every case.

From the original questioner:
I'm asking this question because we're experiencing glue line failures in maple hardwood glued cabinetry panels. Frozen glue or lightly frozen glue was one possibility I haven't eliminated. I will have some panels tested in a lab. He said that under a microscope he could tell if I'm dealing with frozen glue. My tote of glue did not look like cottage cheese. Some guy told me to spread out on a piece of glass to see if it became clear the glue was fine. If it became opaque it could have been frozen.

From Jeff Pitcher, forum technical advisor:
It's definitely possible that some glues are not freeze/thaw stable and will therefore not be useable if frozen. However, it's far more likely that the glue is being used in temperatures which are too cold thereby resulting in chalking. This would be readily apparent by looking at your failed glue line.

From contributor A:
If the adhesive you were using was interior, and it froze, thawing and mixing without churning would solve the problem. What most adhesive manufacturers won't tell you is that you can add up to 2% water to thin down the viscosity. If it is to thin you can add nutshell flour to thicken it up.

Water increases the already present moisture in the wood. Cure takes place once the water has distributed itself in the wood fiber and evaporating into the air. If you were using a PVA, and it froze, (key point) keep in mind that water is in the glue (solids) to make the glue mobile, to get it from the applicator to the material being glued. Water freezes more quickly than solids, and when that happens, the water separates from the solid. But, if the PVA has been catalyzed, pot-life is now the issue. Even unthawing and stirring isn't going to solve the problem. Once the pot-life has been exceeded, this is where your "cottage cheese" effect takes hold and it is of no use to you.

From Gene Wengert, forum technical advisor:
With hard maple, it is most common to see failures because the surfaces are not freshly prepared. Fresh surfaces are more active (chemically) and are still flat. (Are you familiar with the water drop test to test for surface activation? How long between surface preparation and gluing)?

It is also possible that the surfaces in a wood like maple have been burnished by saws that are not sharp. If you are sawing off a ripped edge, remember that it is the sides of the teeth that are preparing the surface to be glued; so it is critical that the saw be properly side-dressed and not just sharpened. Try a different saw sharpening shop and see if that improves the glue joint - many saws are not well sharpened.

Incidentally, in most cases, looking at a joint under a microscope does not show much about why it failed; you can learn just about everything using only 10x or 15x magnification. I also believe that challking does not indicate prior freezing on the adhesive. It can indicate cold wood.