What is responsible for curing urethane?

The correct choice highlights the role of humidity in the curing process of urethane. Urethane adhesives and sealants typically rely on moisture in the air to initiate and complete the curing process. In a humid environment, the moisture interacts with the isocyanate components in the urethane, which causes a chemical reaction that leads to curing. This reaction is crucial for achieving optimal strength and adhesion of the urethane material.

While heat, pressure, and oxygen can influence various adhesive bondings in some materials, their roles are not as central to the urethane curing process compared to humidity. Heat may speed up certain chemical reactions but is not a primary curing agent for urethane. Pressure can affect the application of adhesives but does not play a direct role in the curing chemistry. Oxygen’s role is also less critical, as urethane systems primarily rely on moisture for curing rather than oxygen presence. Therefore, understanding the impact of humidity is essential for effectively working with urethane materials in various applications.