UV light is a very common surface finishing process in the packaging and printing industry.  If the adhesion of UV varnish is insufficient, printing products will appear on the surface easy to fade, wear resistance, gloss off and other kinds of quality problems, resulting in a series of adverse reactions.  In order to avoid the occurrence of such problems, a comprehensive analysis should be carried out, including material procurement, process arrangement, standardized operation and other links, and purposeful rectification should be carried out according to existing problems. 

Reasons and solutions for insufficient adhesion of UV varnish are summarized as follows:

1. UV varnish or base oil expiration due to long storage time.

2. UV varnish and base oil do not match

3. Short ink drying time or drying performance is not good, easy to cause poor UV varnish adhesion. 

4. UV lamp illuminance is not enough, resulting in insufficient UV varnish curing

5. UV varnish or bottom oil mixed with too much water or alcohol, affect the adhesion of UV varnish. 

6. Improper operation affects the curing effect of UV varnish

7. The curing speed of UV varnish will be correspondingly slow in the case of low temperature and high humidity in the workshop

8. The speed of glazing equipment is too fast, cause the curing time too short .

9. UV varnish layer is too thick,  it will not only cause UV varnish difficult to cure completely, but also increase the cost,  even lead the varnished printing products burst during die cutting indentation, directly resulting in obsolescence.  

10. Paper water content, printing surface powder spraying too much and other factors, will also cause a significant decrease in UV varnish adhesion.  Therefore, use of fountain solution and dusting powder should be strictly controlled in the printing process .