On Soy Inks

The debate over soy vs. oil. vs. rubber (and vs. acrylic, don't forget) rages on: last week the discussion about the pros and cons of each variety was being hotly debated on the Photopolymer Listserv, where an astute member referred us to this great post from the Spark Stationery blog. You can read the full post here, but here are the highlights, quoted directly from their post:

* When we looked into the actual composition of various inks, it turns out that soy inks are not vastly different. If not soy oil, most oil-based inks use linseed oil, which has been used for centuries in oil paint, etc. It also is plant based, and time proven. The breakdown of the ink is something like 20-30% oils (of either kind), 10-20% pigments, around 40% resins, and some other things such as drier or varnish.
* In the very small quantities we use, there is no significant difference in VOCs emitted, or other environmental standards. Soy ink shows these advantages in large print runs such as newspapers, national mailings, and so forth.
* The soy ink that is readily available to us is sort of “soupy,” and requires adding modifiers to reach the desired stiffness. Thinner inks make the printing appear sloppy as they “squeeze out” under impression.
* The drive for soy inks came from a marketing council of soybean growers. When a printer of our size proclaims their use of soy ink, we wonder if it is more of a marketing tool than a concrete environmental difference. If the soy oil replaced volatile solvents like toluene or benzene it would be a clear advantage, but linseed has worked well for ages and has no ill effects that we know of.
* We mix all of our inks by hand so even though we are a commercial letterpress shop we only have a can or maybe two of just the pantone mixing inks instead of buying a new can of a single PMS each time someone orders a new color. Common print jobs typically use a small amount of ink – about the size of a quarter. This helps us to be better to the environment instead of having a bunch of ink that might not ever get used sitting around.
* We've also decided to start making the switch to rubber-based inks because of their anti-skimming properties. This keeps more of the ink more usable over time.