The Low-Down on Laying Down Coatings and Varnishes 
Friday, June 30, 2006, 12:41 PM - Coatings & Finishes
Aqueous coating, is what we usually apply to the front side of any mail piece. There are some advantages and disadvantages to aqueous coating: First, aqueous coating is not an ink, nor a varnish, it is actually an ammonia based clear coat that can add great scuff resistance to postcards, as well as increasing overall sheen and gloss factor. Aqueous coating is available in both a high gloss, and a matte or satin finish. Aqueous coating dries instantly, greatly reducing the necessary dry time, so we can print the back faster, and we can cut/finish the printed material straight off of the press. Aqueous coating is relatively environmentally friendly (unlike UV which is plastic based, extremely environmentally caustic, and can not be recycled after it is applied.) Aqueous coating, does lend difficulty with imprinting, writing, or ink jet addressing for mailing, so usually we only apply it to 1 side of postcards, unless we are certain, they will be labeled before addressing. Another down side is that aqueous coating is applied in a "flood" unit, meaning that we must coat the entire sheet, unless we hand cut a blanket for application, which is both manual, disposable, and relatively expensive. Another advantage of aqueous coating, is that it can be done in-line with the printing, and is therefore relatively easy and cheap.

Varnishes, are actually pigment-less inks, (with special additives for scuff resistance, and sheen). Varnishes come in matte, gloss, and a variety of other finishes, and can be applied with printing plates. This allows us to apply "spot gloss", or other finishes to any part of the sheet that you like. This application would be perfect for the look that you are after. There are some drawbacks. First of all, because the varnish is an ink, there is a limit to the amount of coverage that we can put on the paper in one pass ( too much ink, will not dry, or actually begin to cause "picking" where the finish of the paper actually falls apart from the tack of the ink). Also putting varnishes over wet ink, will reduce the gloss contrast, because the varnish vehicles (non pigment ingredients) will mix with the vehicles of the inks. For best results with spot varnish, we usually do a dry trap (print the color, allow it to dry, put the job back through the press and print the varnish). This can really add to the cost of producing your job, because it takes us 2 passes, creates longer drying times, and must sit for as long as a couple of days before it is dry enough to cut, or do other finishing..

In short, for the best value, if you want quick, easy and high quality, I would go with a flood aqueous. For some custom jobs, this is does not produce the desired effect, however. Spot varnishes can be applied at an additional cost, and longer turn-around times. I would recommend getting a price quote on both methods, and making your decision based upon value vs. appearance of the piece.
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