The majority of adhesives (glue) start the curing process when exposed to air. While in a container or a tube, adhesive usually stays in liquid form until it is ready to be used. UV adhesive remains in liquid form both in its container, and outside the container as long it is not exposed to any form of ultraviolet (UV) light.
When this type of adhesive is exposed to a UV light source, a chemical reaction is immediately started, which then cures and hardens the adhesive, usually in a few minutes. Once activated, this chemical reaction cannot be stopped. Rays from the sun also emit enough ultraviolet light to cure this adhesive, but it can take a very long time, often with mixed results.
Learn more: Tips for UV Adhesive Bonding of Color Bases