UV glazing plays an important role in flexo printing and is generally used online. The UV curing unit consists of two UV tubes and a reflecting device. Water-based inks can be printed with UV varnish after printing, which can protect water-based inks. Some faults often occur during UV glazing.
The main reason for the yellowing of UV varnish after curing is twofold: UV varnish is left for too long, especially the yellowing of inferior varnish is more serious; UV irradiation is excessive, and UV varnish is excessively cured. Solution: If it is the quality problem of UV varnish itself, you must replace the UV varnish; if it is caused by overexposure, reduce the power of the UV source or increase the glazing speed.