Epoxies have been used to repair decayed and damaged wood here in the U.S. for at least 4 decades. The first materials that were developed ( and some still in use today ) uses an older epoxy chemistry that relies on micro-balloons to add thickness and to create a paste like consistency.

As this older chemistry cures it age-hardens and turns brittle. 

These materials fail in two distinct ways: Adhesion and Cohesion failures. 

Often the failure of the epoxy repair is not discovered because it is camouflaged as paint failure:

Adhesive failure is caused either by poor surface preparation or an epoxy material that lacks a strong adhesive bond. 

Failure to remove gray wood ( click here for more information on gray wood and epoxy failure ) and decayed wood prior to the application of the epoxy will also contribute to adhesive failure.

Cohesive strength is the integrity of the material itself to move and withstand cracking under stress. Paste materials filled with micro-balloons lack the high flexural strength needed to repair wood.

The Dura-Fix line of flexible wood repair epoxy provides an excellent bond to wood fibers when used together with proper surface preparation. Dura-Fix is engineered with a high flexural strength to resist cohesion failure and will not harden with age.

For more information on Dura-Fix Slow Cure contact: John@nxtgensys.com