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Caulking Tips: Cohesive Failure With 3 Point Adhesion

What is cohesive failure?
Cohesive failure is when the caulk line cracks or tears down the center.

Caulking Tips: Possible causes & solutions to cohesive failure:

caulking tips Problems with 3-point adhesion of sealants: they can’t properly stretch.

Cause #1: 3-point adhesion
The caulk bead is sticking to the back of joint, as well as the sides, and the caulk can’t stretch correctly. Avoid this by inserting backer rod (foam rope, widely available at hardware stores) into any joint that is 1/4″ wide and 1/2″ deep or larger.


Cause #3: Caulk Not Allowed to Properly Cure
Caulk applied in freezing temps or hot temps can’t properly cure and form all of its necessary performance characteristics, compromising elasticity and adhesion of the caulk. Be sure to carefully follow the manufacturer’s application instructions where it states the type of temps you need during application.

Cause #4: Too little caulk applied
A tiny 1/8″ wide joint does not accommodate enough caulk to both adhere to the sides of the joint and leave enough in the middle the stretch properly. Or, as is the case with big round logs, a small 1/2″ bead isn’t wide enough to accommodate the shrinkage and movement those big logs undergo. Try to apply enough caulk from the get-go, but understand that there may be some repairs to do when you can’t.

For each instance, the solution is the same: