glue strip

A glue strip is a continuous or nearly continuous line of adhesive laid along the edge, face, or joint surface of one workpiece to bond it to another. In woodworking, it is the most basic joining method: you apply glue as a narrow strip or bead, press the pieces together, and clamp them until the adhesive sets. The width and thickness of the glue strip depend on the joint type, wood species, and the adhesive used.

Common adhesives for glue strips are yellow polyvinyl acetate (PVA), urea formaldehyde, and polyurethane. PVA is the standard choice for interior work because it is inexpensive, sets quickly (5 to 15 minutes handling time), and creates negligible creep. Polyurethane glues require moisture to cure and expand slightly during setting, filling gaps but also creating squeeze-out that must be cleaned before hardening. Application methods include a brush, a glue gun, a roller, or a thin spreader; production shops often use automated glue applicators that lay beads of precise width.

Joint performance and common failures

The strength of a glued joint depends on the amount of adhesive, the pressure applied during clamping, and the condition of the surfaces. Too little glue starves the joint; too much creates thick, weak bondlines and messy squeeze-out. Surfaces must be clean, dry, and ideally planed or sanded within hours of gluing, because oxidized or dusty surfaces reduce adhesive penetration and strength. Open assembly time (the period between application and clamping) varies by adhesive and temperature; exceeding it allows the glue to begin setting prematurely, resulting in a brittle, weak joint.

Edge gluing, where a glue strip is applied to the long grain edge of boards to join them side by side, is especially common in panel making and tabletop construction. The glue strip must be thin enough that clamp pressure distributes it evenly across the joint but thick enough to fully wet the wood fibers. Grain raising, where water in the adhesive swells surface fibers, can be reduced by dampening the wood slightly before gluing or by sanding after the glue sets.

The term glue strip is sometimes used interchangeably with glue bead or glue line, though glue line more often refers to the thin cured joint itself. In structural applications and marine woodworking, thicker glue lines or glue joints applied with greater precision replace simple strips; production cabinet makers use glue strips on frame-and-panel assemblies and edge jointery daily.