Back Seam

When gluing guitar backs, it is not necessary to have a perfect seam all the way. The back joint reinforcement strip, which is cross grained, the back bracing, and the end / tail blocks will take most of the strain. Besides that, the back is almost entirely in torsion, so the seam is essentially pulled taught.

In order to avoid having open seams, make sure the two halves are jointed with no light passing through when held to a light source, glue and clamp before cutting to size, in order to provide even pressure.