1. Types of Gloss Finishing Technologies for Printed Paper Products.
These processes include coating varnishing with infrared drying, coating calendering (polishing), and UV varnishing with ultraviolet curing. Each method has its own characteristics, advantages, and limitations.
2.Methods for Applying Varnish to Printed Paper Products.
The three main methods of applying varnish are brush coating, printing-based coating, and dedicated coating-machine application.
Brush Coating:
One method uses a dedicated brush to apply an even layer of varnish to the printed surface. After drying, a glossy film is formed. Another method uses mechanical spraying to atomize the varnish and distribute it evenly over the printed surface. This method is particularly suitable for rough, uneven, corrugated substrates, and irregularly shaped packaging containers.
Printing-Based Coating:
This is usually carried out using a printing press. The varnish is placed in the ink fountain, and a solid-area plate is used to apply one or more coats according to the finishing requirements. This method does not require additional equipment, allowing the same press to be used for both printing and varnishing. It is suitable for small- and medium-sized printing plants.
Dedicated Coating-Machine Application:
This is currently the most widely used method. A dedicated coating machine typically consists of a printed-sheet conveying system, drying system, mechanical drive system, and electrical control system. It can handle various types of varnishes and provides precise control of coating thickness, stable coating quality, and consistent results, making it suitable for a wide range of printed products and finishing grades.
3.What Are the Quality Requirements for Varnishing?
1. The varnish layer should be even and free from pinholes, bubbles, and uncoated areas.
2. The coating amount should be properly controlled so that the coating can dry and form a continuous film at the specified temperature and coating speed.
3. The coating should not be adversely affected by the printing ink properties, printed image/text, or ink density. It should have good leveling and provide adequate adhesion to the printed surface.
4.During polishing, the coating should adhere to the calendering belt during processing and then be easily peeled away from the belt after cooling.
1. Types of Gloss Finishing Technologies for Printed Paper Products.
These processes include coating varnishing with infrared drying, coating calendering (polishing), and UV varnishing with ultraviolet curing. Each method has its own characteristics, advantages, and limitations.
2.Methods for Applying Varnish to Printed Paper Products.
The three main methods of applying varnish are brush coating, printing-based coating, and dedicated coating-machine application.
Brush Coating:
One method uses a dedicated brush to apply an even layer of varnish to the printed surface. After drying, a glossy film is formed. Another method uses mechanical spraying to atomize the varnish and distribute it evenly over the printed surface. This method is particularly suitable for rough, uneven, corrugated substrates, and irregularly shaped packaging containers.
Printing-Based Coating:
This is usually carried out using a printing press. The varnish is placed in the ink fountain, and a solid-area plate is used to apply one or more coats according to the finishing requirements. This method does not require additional equipment, allowing the same press to be used for both printing and varnishing. It is suitable for small- and medium-sized printing plants.
Dedicated Coating-Machine Application:
This is currently the most widely used method. A dedicated coating machine typically consists of a printed-sheet conveying system, drying system, mechanical drive system, and electrical control system. It can handle various types of varnishes and provides precise control of coating thickness, stable coating quality, and consistent results, making it suitable for a wide range of printed products and finishing grades.
3.What Are the Quality Requirements for Varnishing?
1. The varnish layer should be even and free from pinholes, bubbles, and uncoated areas.
2. The coating amount should be properly controlled so that the coating can dry and form a continuous film at the specified temperature and coating speed.
3. The coating should not be adversely affected by the printing ink properties, printed image/text, or ink density. It should have good leveling and provide adequate adhesion to the printed surface.
4.During polishing, the coating should adhere to the calendering belt during processing and then be easily peeled away from the belt after cooling.
