The photoinitiator is a kind of additive which utilizes energy from ultraviolet or visible light to induce polymerization and to cure coating and ink. An ink or coating containing a few percentage of photoinitiator can dry in less than one second under a UV light radiation <br /> UV curing offers several important benefits to the customers. First, UV curable coating which formulated with photoinitiator is a new kind of environment-friendly product. The coatings and inks are virtually solvent-free and will not emit any volatile solvents during the process of solidification or so-call “drying” process. Secondly, UV curing uses much less energy than conventional curing. Finally, by using photoinitiators, the UV curing process shows much better coating results with a beautiful high gloss, shining, and scratch resistance coating surface.