Should I use salt in my glue to prevent slipping?
While I was gluing up four boards face-to-face recently, my neighbor noticed how the boards slipped around as I tightened the clamps. He suggested sprinkling a little salt onto the glue before sandwiching the boards together for extra grip while I lined up the edges. Is that a good idea?
—Herm Keller, Spokane, Wash.
Leave the salt in the kitchen, Herm. According to Jeff Loflin, glue specialist at Franklin International (maker of Titebond wood glues), salt (and sugar, too, by the way) can react with wood glue and alter its composition, resulting in a weakened joint.
Rather than resorting to parlor tricks, apply good gluing and clamping techniques. Too much glue in a joint, especially laminations, acts as a lubricant, letting the boards slip and slide. Instead, spread a thin, even coating on the mating surfaces; use a spreader or roller to even out the glue.
When clamping multiple workpieces together, uneven clamping force can cause the boards to slip around. To avoid this, gradually add pressure throughout the joint for each clamp. Realign any workpieces as you go by hand or with gentle mallet taps. As you slowly increase clamping force, the glue tacks up and holds the boards together. Continue tightening the clamps alternately until you see squeeze-out at the joint lines.