I'm working on a piece in process black (or possibly PMS black 7) and silver (metallic PMS to be defined) and want to include a photograph as a duotone. I've read around about metallic inks not behaving like usual inks. What are some issues I should keep in mind when working with metallic inks in duotones? What are ways to get a nice effect?
I'm wondering if I overprint the black on silver if it's going to look all metallic or if it's going to cancel the effect?
When working with metallics, there are a few rules to keep in mind:
Work with a printer who has experience with them. This is not something to embark on with someone just as inexperienced as you are.
Although there are cases where you can half-tone black on top of a metallic, such as for specialty photo reproduction, there are some metallics that won't accept overlaid ink. Be sure to check.
Metallic ink requires a large surface area in order to achieve a good sheen. A metallic half-tone dot screened back 35% or less just doesn't look metallic, period. If you're using this with photographs, then, screen the black on top of the metallic, never the other way round.
Metallics require longer drying time to allow the particles to "leaf" (float to the surface).
Although metallic ink is theoretically opaque, overprinting the metallic on a similar color (white under silver, a yellow under gold, for example) is essential on non-glossy stock, otherwise the metallic particles will almost completely disappear into the pores of the paper. The ink underlay "seals" the paper.
Metallic inks are prone to abrasion, so should have an AQ or UV coat applied for protection. Note, though, that applying a drying coat too soon can inhibit the metallic effect if it dries the ink too quickly.
When you construct your duotone -- I'm assuming here that the other color is black -- be sure to set the profile curve so that there is no or minimal metallic ink in the shadows. Don't just assume that the black will smother it. The metallic particles are reflective, so instead of black shadows you'll end up with a muddy grey.
Always work closely with your printer, and start early in the design process. Ask for an ink draw-down (essentially finger painting the ink onto the stock you plan to use) so you both know what color effect you're getting. Then get a press proof of the final piece so you know for certain before you commit to a long print run.
