re: Biscuit help

I’ve always felt that biscuits added to the strength of the joint in the same manner that tenons, dovetails, floating tenons, dominos, and splines do. They all increase the glue surface and serve to “lock” the joint. If you look closely at a biscuit you’ll see that it is actually a lamination and the grain patterns are not perpendicular. This gives the biscuit shear strength. Since it is compressed, the moisture in the glue causes it to swell which “locks” the joint.

The idea behind a double row of biscuits in thicker material, say a table top, is to increase the glue surface area while adding greater mechanical “lock” to the joint. I’ve used this technique in some exterior applications and had some pretty good success. I firmly believe those tops have maintained their integrity based, in large part, on the presence of biscuits.