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The acrylic substance known as ultraviolet (UV) curing glue requires exposure to that particular light wavelength before complete bonding occurs. The benefit of using UV curing glue is the ability to bond dissimilar objects quickly. The glue and UV curing systems are used in home craft applications and in industrial settings.
The UV lights used for curing emit light in wavelengths ranging from 320 to 400 nanometers. When exposed to the light, a photochemical reaction initiates the glue hardening process. Depending on the type of glue used, bonding may occur immediately or in one to two minutes. Some substances require an additional one to two hours before adequate bonding occurs. Individuals typically apply the glue to the object as small dots in the location, number, and size suggested by the manufacturer.
UV curing glue comes in a clear, white, or colored base. Some brands even contain decorative glitter. To ensure adequate penetration of the shorter wavelengths of the UV light, at least one of the objects being glued must be transparent. The adhesive provides a strong bond when used to join glass with glass, glass with metal, or glass with wood. Curing does not require specific temperatures, and once complete, the bond is usually not affected by atmospheric temperatures.
This glue does not require special ventilation because the substance does not contain toxic fumes. Manufacturers suggest, however, that individuals use eye and skin precautions because the wavelength necessary for adequate curing may cause damage. Most manufacturers also sell protective eyewear and shields capable of blocking harmful UV-A radiation. Industrial applications for UV curing glue span a wide range of possibilities, including circuit boards used in aerospace technology, electronics, and telecommunications. Common uses include adhering crystals to watch faces, jewelry repair, and windshield repair.
Light curing equipment ranges in size from a single tabletop spot lamp, or flood lamp, to conveyor's models. Some of these machines sit on a table and contain curing areas measuring six inches (15 cm) in width. Larger floor standing models contain curing areas measuring up to 25 inches (64 cm) in width. The conveyors may contain up to eight lamps on the sides and top of the machine, providing a full 180 degrees of UV exposure.
The lamps used for UV curing glue typically last for up to 3,000 hours. After this time, the wavelength diminishes in capacity. Users commonly use radiometers to measure the light intensity for quality control or safety purposes. This battery operated handheld meter attaches to a probe that is like the small mirror dentists commonly use to look at tooth surfaces.