Combating Glue’s Too-Many Adhering Qualities
Many fine woodworking efforts and furniture repairs have been spoiled by lack of knowledge about glue.
Two good wood glues we recommend are white glue and carpenter’s aliphatic resin glue. Both have superb holding power, but white glue allows a bit more working time than the professional carpenter’s glue.
The single biggest error in gluing wood is to use too much. Excessive glue actually produces a weaker joint. The correct way to use glue is to spread a thin layer on both surfaces to be joined, let the glue get tacky to minimize sliding action and then press the pieces together.
Except for contact cement, you should apply clamping pressure immediately and let the piece rest at least 24 hours.
Wiping off the excess glue that squeezes out of the joint is the wrong thing to do as there will be an almost invisible layer of glue left on the soft and absorbent wood surface. You may not be able to detect it before staining or otherwise finishing the piece, but watch it pop up as soon as stain is applied.
The correct method for removing excess glue from a joint is to let the welt of glue dry untouched. Then, carefully remove it with a razor sharp wood chisel, bevel edge up. Hold the blade edge at a slight angle to the glue line to remove flakes of hardened glue as you slice them off the joint.
Follow up by sanding the joint with a piece of 120-grit paper backed up by a wooden block.
Glue spots on your projects can be another problem. They commonly appear when you get glue on your hands and transfer it to the project. Your obvious reaction is to wipe your fingers either on your trousers or on a rag. Unfortunately, this generally does not remove all traces of the glue from your hands.
Perspiration may keep it from drying, so whenever you touch the work piece, you risk contaminating it with glue. This is probably the biggest reason for those ugly white spots on shop-made furniture.
Glue left on the surface of the wood acts as a sealer. This means the stain won’t penetrate in these areas. One trick some pros use to keep their hands both dry and free of glue is to put a box or can of sawdust in a convenient spot on the workbench before gluing.
Then, as they work, they frequently pick up a small handful of sawdust, rub it between their hands and discard it into a trash barrel. The dust acts like a blotter to keep their hands free of spot-producing glue.
Once glued, the work piece should be held together tightly while the glue sets. A variety of clamps can be used to handle this part of the job, or you can improvise. By padding the work, you can weight it with heavy books or even a concrete block.
The trick is to set up your jury-rigged clamping arrangement and then depart, leaving the work to dry without vibrations from working on other parts of the project or accidentally bumping into it.
For smaller clamps, there are a number of make-do systems that work. You can cut sections from an old inner tube to make oversized rubber bands to hold parts.
Spring-loaded clothespins make fine small clamps. Other alternatives include locking pliers or even ordinary pliers with a couple of rubber bands wrapped around the handles to provide the squeeze.