Q: Our kiln-dried lumber is stored in an unheated building until we are ready to use it. We then bring it into the plant and cut and glue right away with a PVA. I think that the cold wood in the wintertime is interfering with our gluing. I ran a test and if the wood warmed for a day, it glued better. Am I correct that cold wood is not a good idea when gluing?
A: There is no doubt that the temperature of the wood, especially the surface temperature, is very important when gluing wood. The wood temperature immediately affects the adhesive temperature. Your PVA adhesive is designed to work within a narrow temperature range.
If the wood or adhesive is too cold, then the adhesive will become thick and will not flow well and will require a longer time to set. In some cases, the adhesive will cure so poorly that the joint will be very weak. On the other hand, if the wood is warmer than normal, the adhesive will be warmed and become too thin. With a thin adhesive, you may not achieve a satisfactory spread rate or you may have curing before the pressure is applied, both leading to a poor joint.
I suggest warming the wood for a day before you begin cutting and gluing. Also, contact your adhesive technical representative to make sure you are using the best adhesive formulation. You may need two different formulations for wintertime and summertime use.
One additional comment. When cold lumber is brought into a warmer room, it would be common for the surface to temporarily pick up moisture (like a glass of ice cold lemonade in the summer). This condensation can create some strange moisture meter readings temporarily until the wood warms. Also, some moisture meters require an adjustment for wood temperature.
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