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UV curing is a process in which exposure to ultraviolet light causes a fluid or film to cure. During curing, the chemical compound sets up and hardens into its final form. UV curing is used for a wide assortment of products including adhesives, resins, inks, and coatings. Companies which manufacture products intended to cure under UV light also often sell equipment to be used for UV curing such as lamp assemblies and light bulbs.
There are several different ways in which the curing process can work. All involve some sort of chemical reaction which is triggered by exposure to light in the ultraviolet area of the spectrum. Classically, this is accomplished with a blend of a material and what is known as a photoinitiator, a chemical which will start a reaction when it is exposed to light. In the case of a product designed for UV curing, the photoinitiator only works when it is exposed to UV light.
The specific wavelength of the light usually matters. Many products are designed to cure when exposed to light between 200 and 400 nanometers, also known as UVA, UVB, and UVC light. The product usually indicates the intensity and wavelength needed for curing so that people use the appropriate equipment. Failure to use the right equipment can result in a bad cure which creates discoloration, cracking, stickiness, and other problems.
One big advantage to UV curing is that it can be designed to work very quickly, providing rapid curing so that assembly lines are not held up with waits for curing to finish. Additionally, people can work at their leisure with the uncured material, because it will not cure under regular room light. Curing too quickly is a common problem with many epoxies, inks, and related products which can be avoided through the use of UV curing.
Something to be aware of when working with ultraviolet systems is that even though the light is not visible, it can cause damage to the eyes. People should wear eye protection and should avoid the area, if possible, while the lights are on. Most ultraviolet lights do emit some visible light, which can serve as a warning to alert people to the fact that the lights are on. It is important that technicians and people who work in the facility are aware of the dangers of excessive UV exposure so that they can take precautions.