Sand Biscuit Joints After 24 Hours
I recently edge-glued several cherry boards to make a top, and used biscuits to align them. I let the glue dry, sanded the top, and then applied the finish. As I was putting on one of the last coats, I noticed indentations along the glue lines where the biscuits had been placed. What caused those indentations, and how can I prevent them?
Jack Eilder, Caledonia, WI
The dentis on your top appeared because you sanded it too soon after the glue-up. Biscuits are compressed during manufacturing and when glued into the slot with water-based glue, they absorb water from the glue and swell. That causes the wood around the slot to swell, too. As the glue dries, the water evaporates and the biscuit and the wood around the slot shrink. If you sand the surface before that process is complete, the wood continues to shrink, forming the indentations…