Printing 101

Baby Steps To Print Purchasing Know How

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Aqueous Coating : The Finishing Touch

The most common reasons for adding a coating over your printed piece are for protection: to avoid scuffing the ink, if you have included areas of heavy ink coverage. First consider why you are coating your job.

The decision to apply coating to a printed piece should be based on the following facts:

Unprotected dry printing inks will attract the oils in the human hand and cause fingerprints and scuffing of the ink surfaces, with the most affected areas being the dark solids.

Press applied coatings such as varnish and aqueous coatings are less costly than coatings applied after printing (off-press) like UV coating and film laminates. All off press coatings are applied over dry inks at slow speeds. When applying off press coatings the adhesion of the coating to the dry ink has to be considered as some inks will not adhere to certain coatings or laminates and flaking or de-lamination of the off-press application can occur.

Applying the aqueous coating to a sheet prevents scuffing, gives it additional gloss. When a printed piece such as a publication or brochure is printed without a coating, the rubbing of one sheet to another, to a folder or to a package will scuff the dry unprotected inks. The aqueous coating is an eco-friendly product and water based coating that is dry much faster than an oil based varnish. This enables a faster thru-put of a piece through the bindery process.

Aqueous coating is not available to heat-set web printed products, and only varnish may be applied for the protection of the images.

If you plan to be writing or rubber-stamping, or otherwise marking a sheet, do not choose any aqueous coating as the coating will limit your ability to write on the sheet. The application of the coating should be the final treatment to the printed image.

Aqueous coating is only recommended for coated sheets, and will be absorbed into uncoated sheets and is not recommended.

Certain inks change the color of the image after the application, and certain coatings yellow with age or discolour the paper. It is important to use hi-quality coatings with optical brightners that enhance the brightness of the paper and the printed inks.

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