Clamping Pressure For Wood Glue

And fourth clamping holds parts in position until the glue cures.

Clamping pressure for wood glue.

As the glued up piece goes through the normal expansion and contraction cycles in response to temperature and humidity changes the elevated forces you squeezed into the wood with excessive clamping pressure keeps trying to return the wood to its original shape. The fine woodworking article also gave rough estimates of the average pressure various clamps are capable of producing. In addition to getting the two pieces of wood close enough together for proper gluing pressure also squeezes out the excess adhesive and pushes the glue into the microscopic nooks and crannies. Second as the glue releases moisture causing the wood to swell clamping overcomes this pressure and prevents the joint from opening up.

Additionally consider how much the moisture in the wood will cause the wood of the joint to swell. In some cases where adhesive is only on one of the mating surfaces pressure also assists in transfer of the adhesive to the other face. For softwoods pine poplar. Dale zimmerman of franklin international maker of titebond woodworking glues recommends 100 to 150 pounds per square inch psi for clamping softwoods and 175 250 psi for hardwoods.

Third it overcomes minor surface imperfections between mating surfaces. Proper clamp pressure will also compensate for any imperfections between the two mating surfaces. When those forces cause a failure it might not involve the original glue joint. During extensive research they undertook on gluing and clamping pressure the only manufacturer s reference the folks at lowell thomas tool found was on the titebond website.