using pigments for etching inks

[freedda]

Hello. I'm new here. I just bought about a dozen pigment powders. I'm a printmaker and I want to mix them with an etching ink "base" to make my own color inks.

To start, I have come up with a rough formula based on the oil absorption and specific gravity of the pigments, which usually gives me a mix of 1 part pigment to 2-4 parts of my ink base (base is basically the etching ink without pigment in it).

I first mix the pigment powder by 'hand' with a palette / inking knife, then use a muller to grind the pigment/ink mixture, working with small amounts at a time.

I assume that most people here are painters, but I have a question about what I'm doing:

I believe that my grinding with the muller is not to actually grind the pigments (which I assume are already ground very fine), but rather to ensure that each pigment particle is well coated and mixed in with the ink base, so I don't have dry pigment particles in my mix. Is that a correct assumption?

I have only mixed a few of these pigments so far: green raw umber and Verona green earth. I have not yet printed with them yet, but they seem the correct consistency and feel, similar to my store-bought inks.

Regards, David.

[George O'Hanlon]

You are correct. Grinding paint (or in your case, ink) with a muller does not actually mean that you are grinding the primary pigment particles to smaller size, but rather you are breaking up aggregates* and agglomerates of pigment particles to make a smooth paste. In the action of breaking up pigment agglomerates, you allow the binder to coat the pigment particles.

* Aggregates are groups of primary particles that form tightly bound clusters. Agglomerates are loosely bound clusters of aggregates and primary particles.

[ 26. August 2010, 15:33: Message edited by: Admin ]

[freedda]

Thanks George. Its a bit of a grand experiment for me. I've heard everything from "go for it" to words of caution: at least in one book I read it said that adding pigments to ink base doesn't work because the pigment particles are too rough and will scratch the plate. I think its worth a try however.

Best, David