letterpress inks

There are two main types of ink used on the letterpress, oil-based and rubber-based. Oil-based dries very quickly and is best for coated stock (where the ink can't soak into the paper) and should be cleaned off the press within the hour. Rubber-based is best with porous paper that the ink can soak into and can be left on the press for days, which is helpful when you are printing a long running job.

Ink is usually sold in 1lb cans, which if you are printing occasionally, is going to last you a lifetime. NA Graphics sells in 1/4 tubes that would be more convenient to the small run printer. I purchase my Van Son Rubber-Based inks from Kelly Paper, which is right down the street from me. They can mix Pantone® colors for me by the next morning for $30 / lb.

I use rubber-based inks because of the ability to print consecutive days as well as the over print effect of layering colors that is a feature in most of my designs, as in "time passages" below.

There is also soy-based ink, which I have limited knowledge and experience with, here is a Briar Press thread about them that seems to be the most concise knowledge I've found.

Pantone® inks used for the letterpress are not "letterpress inks" they are generally made for offset printing (a much larger market), but will work fine with letterpress, but here are a few things from my experience to keep in mind in their transfered use.

1. The Pantone® inks will print darker on the letterpress. The inks are thin for offset use, therefore on the letterpress, to get the right coverage, the color will usually end up the next darker shade on the Pantone® chart.

2. Paper is an added colorization factor. The tone of the paper will interact with the resulting color, here are two cards I used "orange" Pantone® 123, the one on Fox River Confetti Yellow appears burnt orange, while the one on Johannot mouldmade is bright orange.



3. Coverage will effect the color depth. With a light amount of ink on the press, the print results will be light and with heavy ink coverage, the depth will be depended. Both images below were taken under the same lighting conditions, same impression, the only difference is in their ink coverage, which is easily shown here on a image that requires a large amount of ink.



4. Remaining ink residue from previous print runs. If the rollers have not been cleaned properly, they will retain the last colors run and effect your current job. Even with extensive cleaning, rubber rollers hold on to a bit of color from previous runs. Some hints if you are printing a white or transparent-based color are to ink up the press with white, then clean the press (this will remove most of the dark ink stored in the rubber) or if you have the luxury, keep an extra set of rollers just for white/light colors (keeps the dark ink contamination out!)

5. Matching to screen colors or ink jet prints. One of the many mistakes that a letterpress client will make is in the assumption that the final print will be matched exactly to their screen or ink jet print. Pantone colors are like paints, they are specially mixed inks, unlike screen values which are components of RGB (Red, Green, Blue) and print outs use CMYK (Cyan, Magenta, Yellow, blacK). It is impossible to match between screen and prints, alone!

More information on inks are available on this Briar Press thread.