Printing inks are made using a base material, also called a vehicle. The most common ink bases are oils (such as linseed), resins and waxes. By themselves these vehicles are colorless and would hardly be noticed if printed on a sheet of paper. Pigments are blended with the ink base to add color. These pigments may be organic or inorganic in nature and are used to create white ink, black ink and thousands of colors in between. Lastly, chemical drying agents are added to the ink to facilitate its absorption into the paper (or other substrate).

NO, YOU WON'T FIND GOLD IN GOLD INK

The fact is, if you ask your printing company to use "metallic gold" ink for your next project, they will use a formula consisting of an oil base, plenty of drier and very finely powdered bronze. Copper-colored metallic inks also get their sheen from bronze, just a different shade. "Silver" metallic inks, on the other hand, turn to powdered aluminum for their luster.

You may have had the opportunity to pick up a piece of paper printed with metallic ink only to find some of the ink rubbing off. The cause of this "flaking" is the size of the metal particles themselves. As they become larger, the ink loses its ability to adhere to the paper. From your printer's perspective, it's advisable to use a metallic ink that is made with finely-ground metal flakes. However, the ink's shade is sometimes determined by the size of these flakes. In other words, an ingot of bronze will produce one shade of gold when ground very finely and a completely different shade when ground coarsely.

There are some instances, believe it or not, when metallic inks never completely dry. However, your printer can work directly with the ink manufacturer to create a specific formulation that takes into account the kind of paper you are using. In addition, metallic inks can be "sealed" with a layer of clear varnish (as has been done with this issue of Printprimer®). While the ink may never fully dry, it will adhere better than an ink made for application on an assortment of papers (or, as printers say, "right out of the can").

COLORFUL METALLICS

In addition to golds and silvers, other colors of metallic ink are available. These are created by mixing colored ink with the powdered metal flakes and varnish. Depending on the color you choose, the ink begins with either gold- or silver-colored metallic ink. The major consideration when working with colored metallics is that as the color becomes darker, the metallic effect becomes less noticeable. That's because richer colors tend to hide or cover-up the subtle, reflective effect. The most pleasing effects when mixing colored metallic inks are achieved using pastels and other delicate color hues. Pantone®, Inc., a company that establishes color standards for a wide variety of industrial applications, publishes a color guide that contains the most common metallic inks used in commercial printing. While virtually any color can be made into a metallic ink, the ones specified in this and other similar guides are generally recommended.