Stop Glue-Up Slip With a Dusting of Grit — or a Pinch of Salt

The Problem

Wet glue eliminates the friction between two boards, so the moment clamp pressure lands even slightly off-center, the boards skate out of alignment — and a panel glue-up with several boards gives you several chances to lose your religion at once. Cauls and dowels work, but there's a faster fix: put the friction back.

The Technique

The grit method:

1. Spread your glue, and before assembling, take two pieces of 40- or 50-grit sandpaper and rub them together grit-to-grit over the open joint. Loose abrasive particles snow down into the glue — a few swipes is all it takes.
2. Press the boards together so the grit embeds into both surfaces.
3. Clamp. The embedded particles key the faces together, and the boards stay where you put them as pressure comes on.

The salt variation:

Use a few grains of table salt instead of grit when you plan to saw, plane, or turn through the joint after it cures — embedded abrasive dulls and scratches cutting edges; salt doesn't. Two cautions: clamp up before the salt dissolves in a water-based glue, and go sparingly. Tape over the shaker's top and leave one hole open — too much salt and the joint won't close under clamps.