If you have Cautionary Tales to tell about metallic inks, you’re not alone. They’re a different animal than most other offset inks and they present unique technical challenges. This article explains some of the characteristics of metallic inks and offers tips for working with them successfully.

Two Cautionary Tales

One designer told me about a brochure project he’d designed that included metallic silver ink. Of course the client was in a big hurry to get the printed brochures, he said. The printer did not think to protect the ink with a coating, did not allow enough drying time, and crammed the brochures tightly into a carton for delivery. Each brochure offset or transferred silver ink from one brochure onto the next. Yikes!

Another designer friend described trying to print black 8 pt. Helvetica Light type on a silver map that included several screen tint values. He commented that it was impossible to tell from the digital proof whether the black type was overprinting or knocking out of the silver, but it looked fine on the proof.

It turned out that the black was set to overprint, so on press it showed up in several values of silverish-black. The designer reported solving the problem by switching the map art from metallic silver to PMS 429 gray.

Metallic ink characteristics

Most offset printing inks are translucent. But metallic inks are opaque, or nearly so. That’s because metallic inks contain itty bitty flecks of genuine metal. This opacity can work in your favor when you want to lay down a large metallic solid—you can often get good results with one hit. Opaque metallic inks can also be printed on dark papers. (More about that later.)

As metallic ink dries/cures, the metal flakes rise to the surface of the ink layer, making it look more shiny. If you don’t like the way the ink looks at press, refer to the drawdown as a more accurate guide than the wet ink. Then be patient, it’s going to look more shiny tomorrow!

To trap or overprint, that is the question

Black type overprinting 100% metallic platinum

Trapping metallics with non-metalic inks is tricky because the metallic ink trap sometimes looks “haloed” against the regular ink or forms a slight ridge. Experienced printers get around this by setting a skinnier width of trap line. This approach is not feasible on small or thin type.

As noted in the Cautionary Tale above, overprinting on a field of metallic ink can also be problematic (though I’ve seen it done well), because you can see the opaque metallic through the overprinted translucent ink. Even black can look muddy.

When type is small and fine, overprinting is the only option. One printer I work with suggests using a lighter screen of the metallic instead of 100%, then overprinting the flat color. This has worked well for me.

Another solution is to use Pantone Black 7 for a more opaque black. It has PMS 877 silver in the mix. Black 7 tends to read as a dark charcoal rather than black.

Reflectance and Screen Tints

The metal flakes also change how the light reflects off the printed sheet, causing enough interference that screen tints often read differently than expected, usually darker, but not always. Many designers really like 90% screen tints, but a 90% metallic may read very close to 100%!

Sometimes the right adjustment to the screen tint is counterintuitive. In general, though, avoid the extremes of a 10% or 90% tint or the subtlety of 5- and 10% steps. 15- to 20% steps (like 15%, 30% and 50%) are more likely to give reliable, perceptible contrast between tints. In short, subtlety can be difficult to achieve with metallic inks.

Metallic ink projects are good candidates for stochastic screening, in my experience, especially if you want to overprint tints of silver. This sidesteps moiré issues.

Paper Choice Matters

Annual report printed on coated dull stock

But designers like subtlety! I’ve seen them disappointed with how non-metallic the metallic inks turned out on uncoated papers. If you use metallic ink + uncoated paper, be prepared for subtle results. Maybe too subtle. I feel that using metallic on uncoated is a bit of a waste. Silver is likely to look gray. Gold or copper may look blah brown.

The reason the metallic looks so flat has to do with the way light strikes and bounces off the rougher surface of uncoated paper—that shine is diffused rather than bounced directly back toward your eyes.

If you are aiming for maximum shine, print on a coated stock—the glossier the better. Coated stocks have more ink holdout, which means that less of the ink is absorbed into the paper fibers. It sits atop the paper instead, where it can work up some serious shine. Gloss coated stocks are highly reflective to begin with, so they’ll add the “light bounce” back to the eye that will enhance a shiny read.

Dull stock yields softer shine

Next best is dull stock. Matte stock is closest to the diffuse surface of uncoated stock, so it will have the least shiny read of the coated stocks.

Metallic Inks on Dark Backgrounds

The best approach to printing metallic inks on dark paper will depend on how dark the background is. For the highest contrast and the most pop on very dark paper (such as chocolate brown, dark blue, or black), the printer may suggest laying down a first hit of opaque white under the metallic ink. This solution requires the printer to hold very accurate registration of the metallic to the white ink, because if the white is choked in very much, that undesirable halo effect may occur.

Speaking of Body Copy

Blocks of type printed in metallic ink, especially silver, can be very hard to read. When a designer insists on silver type, I recommend adding a tiny bit of black to the ink formula to improve readability. Otherwise, the reader will have to tilt the page to various angles in order to read the type!

Coatings are a Must

Remember those itty bitty metal flakes? Well, they won’t all stay stuck to the paper, so some kind of sealer or coating a must. Unfortunately, any coating will dull back the metallic sheen to some degree. You’ll need a varnish or aqueous coating for envelope flaps or any medium to large solid. Gloss varnish is best. Satin and dull will subdue more shine. Just about the only time you can get away with not varnishing is for light-coverage body copy.

For uncoated paper, use varnish. For coated paper, use varnish or aqueous coating. Be aware that varnish tends to yellow more over time, so it’s more suitable for pieces with a shelf life of less than a year.

In writing this article, I learned something new. Take a look at this metallic page from my oldest Pantone fan. Boy, was I surprised to see that every color except silver had tarnished so severely! I don’t know whether this fan page was varnished or not, but I’ll bet that varnishing also guards against tarnish.

Disaster Avoidance Tips

  • Not every printer has experience with metallic inks. Before you award a metallic job to a printer, ask to see samples of metallic ink projects his shop has produced. Look for trapping halos, clean screens that are not plugged, and clean-looking solids and screens. Discuss how they handled traps and ask about any other challenges the jobs presented.
  • If you have a specific look in mind, provide examples. Duotones with metallic + black can be gorgeous. Give the printer a visual guide.
  • Digital proofs do not simulate the look of metallic inks well at all, so always order ink drawdowns, one half of the paper covered with the selected coating and one half without any coating, so you can see the effect of the coating on the shine level. The drawdowns will be your most reliable visual gauge.
  • Show your design to the printer early in the process. If either of you are concerned about how the metallic colors will read, it may be worth negotiating a small press test—the gold standard (ahem!) insurance policy for getting the look you want.

What’s your experience with metallic inks? If you have more tips for printing with them successfully, please share them in the comments.

© 2010 Nani Paape