Reasons for Adhesive and Cohesive Failures

What are the common reasons for Adhesive Failure?
-Contamination (such as grease, oil, other impurities)
-Application technique
-Substrate compatibility (if a substrate and adhesive are incompatible, adhesive failure can happen)
-Environmental conditions (high humidity, carbon dioxide, PH level, oxygen)

What are the common reasons for Cohesive Failure?
-Inappropriate adhesive
-Environmental factors (heat, cold, moisture, and the introduction of chemicals)
-Surface preparation (cleanliness of the two substrates; grease, oil, dust, or dirt)
-Improper curing of the adhesive (time, airflow, and the amount of pressure used during application)
-Lack of elasticity and strength

What is the difference between Adhesive Failure and Cohesive Failure?
-Adhesive failure is an interfacial bond failure between the adhesive and the adherend. Cohesive failure occurs when a fracture allows a layer of adhesive to remain on both surfaces. When the adherend fails before the adhesive, it is known as a cohesive failure of the substrate.