Ink Mixing: opaque white vs. transparent white

In mixing Pantone colors we encounter the phenomenon of “transparent white”, which in other fields would be called “clear.” Many have found that for letterpress printing, opaque white works better for color consistency or for other reasons. I’ve found that with transparent white it can be tricky to maintain even color over a run, as slight variations in the ink film thickness show much more than with opaque ink.

Since the PMS formulas don’t use opaque white, some adjustments are sometimes required. A pastel color may specify 97 parts trans white to 3 reflex blue, for example. Transparent white ink is actually somewhat yellowish, as it contains linseed oil, resins, and other things essential to being ink. So, often we need to add some yellow into the mix when using opaque white.

Replacing transparent with opaque white is also essential when printing over darker papers. If the artwork will allow it, the piece can be run through the press two or even three times to achieve fairly complete opacity. On a hand-fed press this can be quite a stunt for testing consistency of registration, where on a windmill (for example) you will rarely see a variation if everything’s set right.

Blind Debossing + Ink = GOOD

We've had a number of requests lately for blind debossing and tone-on-tone printing. Now of course this would mean without ink, which honestly is something I prefer to avoid, unless I am using an unusually heavy stock.

One thing I've found to work for Spark's clients is using varying degrees of transparent white ink. I feel it gives the impression just enough definition to make all the difference. When the client wants even more definition without running a color, we'll add in a hint of silver or gold. The gold works especially well on the off-white stocks. Either I need to get more rest, or maybe I just have a decent eye for color, but the transparent white does dry a bit darker than it looks when it first comes of press.

Also, I do make sure I clean the rollers especially well before running transparent white (or any light color for that matter).