Many, if not most of your woodworking projects will encounter gluing, whether you are gluing panel pieces to create a tabletop or cabinet door or a joint. Clamps are involved in gluing, as is the drying time for the glue. Depending on the glue used, the drying time might be minutes or hours, and each glue manufacturer will tell you how long to wait for removing clamps and working further with the wood.
Those manufacturers and glue types, whether Titebond or Gorilla, give us the necessary guidance on drying times and clamping requirements. But what about continuing work on the wood surface, whether sanding or running joined boards through a planer?
This is because glue drying time and curing time are different. And, it also depends on what is being glued since panels for a tabletop and pieces forming a joint are put to different stress levels.
Let’s see if we can help.
Preparing Wood For Gluing
We know that moisture is the enemy of wood. It causes wood to swell, and the expansion and contraction that follows can be problematic in woodworking. So, the first rule is to make sure you are working with wood that is cured.
By cured, we mean that an equilibrium has been reached between the wood moisture level and the moisture level of the surrounding environment such that the wood stops absorbing moisture when exposed to it. Wood that has reached this equilibrium is ready to be worked.
You also want the wood surface to be “clean,” and by this, we mean free from splinters and dust. Sometimes cleaning a wood surface means simply cleaning in the literal sense with a damp cloth. Sanding is also a good and common practice before gluing to remove splinters and then wiping with a damp cloth. There are also solvents that can be used to clean wood surfaces.
Should you plane wood before gluing together?
Smooth wood surfaces will take a gluing well, as there will be no gaps between the pieces being joined. And gluing freshly prepared wood surfaces, whether by sanding or planing, is also recommended.
Planing wood before gluing pieces together is a good practice. The process to follow is both simple and logical:
- Plane one side flat on all pieces to be joined.
- Plane them all to the same dimension, using the thinnest one as your guide.
- Then glue them all flat side down so that any incremental differences are all on the same side of the joined pieces.
- Finally, and after the glue has dried, plane them flat on both sides.
This also answers the question of whether you can run glued boards through a planer.
But, be sure to have wiped any excess glue using a damp cloth when you clamp the wood pieces together. It’s important, too, that the glue be allowed to dry.
Most glues need 30 minutes to 1 hour of clamping, and after that, some light sanding is okay, so long as it does not present stress to glue joints. But, curing takes much longer, usually 24 hours, for the joints to reach full strength.
At the least, allow the glue to dry before running the wood through a planer. This will help make sure you do not clog the planer with any excess glue you might have missed after clamping.
What is a Stressed Joint?
Joinery must take into account the stress that will be encountered in the joints being created. Clean and smooth wood surfaces both play a part in adding strength to joinery, but the type of joint needed in woodworking is determined by the type of stress the joint will suffer.
There are four types of stress to consider:
- Tension
- Vertical shear
- Compression
- Racking
The joinery method chosen must take into account the type of stress the joint will likely encounter. Gluing strengthens the joint, of course, and for maximum safety, allowing it both to dry and cure goes a long way toward making sure you don’t have to start over again. To be even more cautious, wait another 24 hours after curing before subjecting the joint to stress.
Here’s a helpful video that identifies what each of these stresses is.
The short answer to the title’s question is at least 30 minutes to one hour. The safer answer is to wait for the glue to cure. And, if the joint is likely to be more highly stressed, wait another 24 hours beyond.
Follow the steps to prepare the wood surfaces before gluing and the manufacturer’s recommendation on drying time and curing time, and your project will proceed well with little likelihood of having to start the project over.
Sometimes a belt and suspenders are needed to make sure your pants don’t drop. Wait the extra time.