When Joints Fail

A properly executed glue joint will provide many years of structural integrity. The surfaces to be glued must be prepped accordingly, properly aligned, coated in the correct amount AND type of adhesive, clamped with adequate pressure, and be allowed to cure for the correct amount of time. The combination of these actions provides the highest success rate for repairs that are both structural (broken or loose chair or table legs) and cosmetic (loose or missing veneer).

Failed glue joints can often be diagnosed as either one of or a combination of several problems:

Adhesion Failure

This can best be described as the adhesive not properly adhering to the surface (or surfaces) being glued. This can be due to improper surface prep, inadequate amounts of adhesive, or lack of good contact between the adhesive and the surface. If you see the adhesive cleanly on one side of a glue joint, adhesion failure is a likely culprit.

Cohesion Failure

A glue joint suffers from cohesion failure most likely due to a problem with the adhesive having difficulty bonding to itself. Think of a two part epoxy. Thoroughly mixed at the correct ratios, the epoxy will set as desired. Frugal mixing and/or incorrect ratios will result in an epoxy unfit for the job and the joint will fail. Glue on both sides of a failed joint usually indicates cohesion failure.

Substrate Failure

Substrate failure is the result of the surface being glued failing before the glue fails. An example being a chair leg breaking right along a previous break where some wood is still firmly embedded in the now exposed glue.  The glue has done its job and there may be an issue with the wood. It is also possible that misuse or improper handling is the cause of substrate failure.




Adhesion and cohesion failures on our repairs are covered by the Kerrigan Restoration Warranty.