lighter inks

Do you have any limitations on inks with more than 50% opaque white in them. We seem to be finding that it takes a lot longer to get color on pms 543 over a 542. Or that a cool grey 8 ends up needing much more opaque white than the mix called for.

Do other people find more trouble with pastel inks and getting even coverage? Do you have any secrets? What has been your experience?

Thanks and keep the presses rolling.


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The formulae I have for the colors you mentioned all involve mixing with Transparent white to allow the paper reflectivity to come through rather than loading up the pigment (opaque white) to lighten the color. You might double-check the formula you are using an make certain you are using the correct “colors” in the mix.

We “letterpress folks” also have to deal with the idea that we are laying down a thicker ink film (generally) than the formula books consider (most are offset-litho oriented) so we may be putting down a thicker layer of the pigmented material. The formulation must change to get similar effects.

jhenry - I have been mixing with the transparent white and finding that the transparent white ink is much more runny than the other inks. I was thinking about mixing only with opaque white to fix this issue - david - I would like to hear more responses on this since you are having issues with opaque white while I am struggling with transparent white.


It seems to me there are at least three separate issues here. First, I think, is the question of accurate mixing. As jhenry says, the formulas call for transparent white, and you can’t make the recipe with different ingredients and expect the results to be the same. How are you checking that the mixed ink is the right color? Somehow you have to be able to simulate the ink film thickness that would be put down by an offset press, in order to match the sample. I’ve never had much luck doing a “draw-down” to check color, but a “tap-out” on coated stock does work for me. When mixing very light colors it’s easy to be off just a bit on percentage of one of the darker colors going into it, throwing the whole thing off.

Second, again as jhenry says so well, letterpress typically puts down a thicker ink layer — but how much thicker, and how that affects the color, depends greatly on the press, operator, and other variables — and you have to have some idea of how much darker (than the sample) your “average” run prints before you can start to compensate for it.

Finally, Brandi, I’m not clear on the problem with “runny” ink — virtually all printing inks are more-or-less thixotropic and will turn at least somewhat “runny” as they are worked, whether in mixing or by the rollers on the press. And some colors (such as violet) just seem to be thinner than others. But every ink I’ve worked with was still sticky enough to stay on the press in the thin layer we should be using, and transfer to paper fine too. Is there a possibility you’re just trying to print too thick a layer of ink, leading to mottling? Do you have the same problems with different kinds of paper? Any chance you could post a photo?

Dave R. (the Ink in Tubes guy)

I mix with opaque white rather than transparent white. Why? because somebody told me to do that early on and I have never actually tried transparent with letterpress.
I am an offset printer and use transparent when mixing for offset.
Another letterpress printer says he mixes 65/35% opaque white and transparent white.
the conclusion we are coming to seems consistent with what is being said here. Letterpress needs a thicker film of ink. We print almost always on Lettra. There is no sizing in that paper. With offset papers the sizing helps the ink lay down more evenly.
The conclusion we are coming to is with letterpress we are better mixing the next shade lighter ink and then running a heavier ink film to get the color.

Let’s keep mixing it up,


Sounds reasonable. David, so you’re used to mixing and printing offset, and I assume you have no problem matching a color when mixing using transparent white and printing offset. How does the same ink look, printed on the same paper, printed letterpress? How about if you mix the same formula again, but using opaque white? Then how does it look, again printed both offset and letterpress on the same stock?

As an offset printer who mostly taught myself letterpress, nobody ever told me to use opaque white for letterpress so I never have (unless I wanted a more opaque ink for a specific reason). Among other things, transparent white is a lot less expensive than opaque white! I guess I do tend to use the same ink for all of my presses, offset or letterpress, and assume it will work fine until proven otherwise. I also admit to having never printed on Lettra (or any other “letterpress” paper), although I’m well aware that different papers can drastically affect the ink color and end result.

I’m not so sure that letterpress “needs” a thicker ink film, but certain papers do need more ink and letterpress almost always does put down a heavier layer of ink than offset, so going a shade lighter does seem the way to go.