Material that curing with UV light provide an convenient cure. Other compounds that harden at room temperature must be mixed and used within a curtain time to obtain the best result. Typically, there is no mixing required for UV-curing material, nor is there any requirement to be use dispensed material within a short time period.
 
Every high performance adhesive has at least two components to do it, such as the two-parts, room temperature cuing material. A less obvious example would be contact cement, where only a single material is handled. For this kind of adhesive to work, a solvent must evaporate from the product, leaving the actual bonding resin behind. So, the resin is one part and the solvent is the second part.
 
For UV-curing resin, there are also two components as below:
 
1. resin itself;
2. photoinitiator. 
 
Photoinitiator will not react with the resin by itself. The photoinitiator must absorb UV light before anything can be happen. When the UV light is delivered, the photoinitiator will undergo a chemical reaction and produce by-products that will cause the resin to harden.
 
UV light has two important chrematistics: wavelength and intensity. For the photoinitiator to react correctly, it must be exposed to UV light with correct wavelength and sufficient intensity. Otherwise, the chemical reaction will not happen, or may not happen completely.
 
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