Coated photoptic gum is too slow, prone to leaking liquid to ink surface, and can easily lead to gelatinize unevenness, the speed of the fast, easy to produce a pinhole.

• 涂布感光胶速量不适宜功缓、胶液易渗漏到油墨背，而且便当引起涂胶不匀，功迟的速量，便当爆发针孔。