Coatings or Varnishes

Coatings and/or varnishes are used for different reasons in printing jobs. One reason you use these processes is to protect the ink or sheet. Another reason is to give the paper or ink a higher gloss or lustre look.

Varnish is the oldest of the processes and is actually a type of ink. It seals and protects the inks and is on the low end of the amount of gloss or lustre it can produce. Varnish is probably the easiest to apply in a spot area. In other words, just over say a picture or graphic but not on the rest of the sheet. You can apply wet trap or putting it over the ink while the ink is being applied wet. This can reduce the effectiveness of the lustre. You can also dry trap which is applying the varnish by running back through the press after the ink is dry. This is more costly.

Varnish also can gas ghost which is described as trapping the gases of the inks from escaping thus giving a ghost image from the other side of the sheet. Not good when you are printing a 2-sided brochure.

Aqueous coating is the most common way of coating sheets present day and it is a water based coating that usually is applied overall. It has more gloss than varnish and the printed sheet can be handled almost immediately to cut, score and fold your printed products. UV coating is a solvent based coating that is the shiniest of the three processes. It carries environmental requirements in handling but will give the most protection of the three. Usually applied overall it also can be spot UV'ed. It needs special driers attached to the press with UV driers and requires special inks as well.
Products can be handled very quickly after passing through the drier. These are the most common way of coating printed products. All three of these coatings can be done in gloss, satin or dull coatings.

Written by Buzz Tatom
The Odee Company