Mixing Ink: Mysteriously Separates?

Hello! I am new to letterpress and am using the L Letterpress for my wedding invitations. Last night, I mixed Van Son Rubber Base Plus Opaque White and Black to make a gray for my invitations. I mixed approximately 300 grams of the Opaque White with about 2.5 grams of the Black on a glass slab with palette knives. I then scraped the mixture inside a Ball glass jar (the kind with the canning lids and rings).

I went to unscrew the jar today and saw that there were bubbles inside the ink that had popped - so I guess I had forced a lot of air into the ink while I was mixing it. Also, curiously and annoyingly, there were specks of black ink that had oozed to the top. I mixed them back in and went back to the jar some hours later - and, sure enough, there were specks of black ink that were rising to the top of the gray mixed ink, again. (I’ve attached a photo of the separating ink).

Why is my ink separating? Also, should ~ 300 grams ink be enough for approximately 200 invitations + 200 maps?

Thank you!

image: photo (19).JPG

photo (19).JPG

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Not sure why your inks are having issues, I’m sure someone more familiar with ink behaviour will chime in.

It is tough to say how much ink you need without seeing the coverage and size of the pieces in question. But I’m pretty sure 300 grams of ink should be more than enough for what is essentially a relatively short run (though I suspect quite a long run on the L).


Not sure why your having problems. How fresh was the ink. Was there any foreign matter on the glass or the knife. I mix many colors using only six colors of VanSon rubber base ink and never have issues. ( For transparency sake, I did have a problem last year when I mistakenly mixed oil base and rubber base.)
Typically if the color I want is not one of the six I almost always start with opaque white and add small amounts of the others until I get where I want to be. Sorry not to be able to give you a more definitive answer, but something is wrong with one or the other, or residue on the knife or glass, or maybe in the jar, blueberries?

Thanks, Kim! The map is just text, and lines…no large solid areas…around 3.5 x 5.25 inches. Invitation is just text covering an area of about 5 x 5 inches.

Steve - the ink was from an unopened can that I got from another printer a few years ago. When I opened it, there was no skin or dried-out rubbery areas. That being said, I will instead try using my Pantone Mixing Black that I bought last year, and see if that improves the situation.

You made great points, and I’m hopeful that your other questions will help me zero in on a solution. I’ve been cleaning my glass and acrylic mixing plates, palette knives, and rubber brayer with vegetable oil (which dissolves the rubber ink like a dream), followed up with a wipedown with diluted Simple Green. I think this procedure is probably not enough to eliminate oily residue from the vegetable oil. So what I’ll do going forward is to do a final wipedown with deodorized mineral spirits, and then finish with a Dawn dish detergent wash in the sink. Hopefully that’ll get my brayer, knives, and glass and acrylic plates squeaky clean so that no oily residue remains to possibly contaminate and screw up my ink mixture.

I hope this also improves my inking on the brayer - I’ve been having problems with the rubber ink getting too tacky and sticky after just a couple of prints (resulting in a weird mottled “orange peel” texture), so I’ll be turning on the dehumidifier (I’m in California), mixing up a new batch of ink with (hopefully) cleaner tools, and crossing my fingers for better outcomes in both the ink mixing and ink braying realms.

Thank you!!

Is it actually black ink separating out, or is it the medium (the varnish and dryers and such) separating from the pigments? I’ve had inks that wanted to separate that way, especially older metallics. Remember that the pigments are powdered material that are suspended in the medium. Over time, that suspension can break down, especially with the heavier pigment materials like mica or aluminum that the metallic inks often use. It may be that you just have to give the ink a slow stirring before using.

Michael Hurley
Titivilus Press
Memphis, TN

Is the great majority of the ink of the correct color? If so, I would hazard a guess (not having seen the ink in person, it can only be that) that some of the ink got slightly mixed with the oily residue on your mixing plate or knife, and so was caused to separate from the rest. I would believe if you removed that top bit, and the remainder of the ink was A-OK, you could proceed to print without issue. More than likely if given enough milling on the ink table, the oil would blend in and the problem might be resolved.

Let us all know what happens.

John Henry

I have an update! I further cleaned the palette knives and mixing glass slab until squeaky clean (with a mineral spirits wipedown and a good scrubbing with Dawn dishwashing liquid) and made Ink #2 (Opaque White, Trans. White, and the new mixing black), being mindful not to let any residues of oil, soap, etc. contaminate Ink #2. I then let Ink #2 sit overnight and checked on it this morning.

Drumroll, please…

Ink #2 has separated as well. I’ve attached photos of Inks #1 and 2. Ink 1 (the first ink that inspired this post) is the bluish-gray ink with the tiny bubbles, and Ink 2 is the warmer gray ink with the bigger bubbles.

I’m beginning to wonder if ink mixing technique is the problem here. I’m mixing about 300 grams of ink each time on a glass slab of about 8x10 inches. Obviously, I’m working on far too small of a surface here. Perhaps I’m introducing too much air into the mixing process? Maybe I’m not adequately smearing the ink against the slab? All I know is, both inks are quite bubbly, and I’m trying to make ink here, not sourdough starter…

Michael, it just looks like the black ink is rising to the top as the bubbles in the ink (in both batches) slowly pop.

John, the great majority of the ink in both batches is the correct color.

I wonder if milling the ink more would solve my problem. I’ve been spending upwards of 1/2 hour each time on mixing the colors, but maybe I need to focus on smearing them more. On a bigger slab, perhaps…

Thanks, everyone!

image: inks side.JPG

inks side.JPG

image: inks.JPG


It looks to me like the black ink pigment was not properly dispersed into its vehicle during the milling process. You might want to invest in a glass muller and the corresponding textured glass mixing plate. Curious as to whether the ink looks ok when you mix it? Have you tried printing right after the mixing, and how it looks on the paper after it dries?


Hi Paul,

The ink looks evenly-colored but VERY bubbly right after I mix it (consistent with the bubbling in the jars). I have tried printing right after the mixing, and it seems to print up fine; however, for whatever reason (bad speedball brayer? humidity at 60%?), I can only get in a few prints with hand-inking on the L Letterpress before the ink starts mottling on the brayer (and then, on the plate, and consequently on the paper). (This mottling / orange-peel problem happens with all my rubber-base inks, even the pre-mixed ones.).

How are you mixing? Traditionally mixing is done with a flat ink knife on a slab of glass or marble in long motions folding the ink, gathering in a long motion, and drawing it down, not stirring which is inclined to create bubbles. Any bubbles should basically be pushed out by using the knife in a flatter motion. It’s more like blending the ingredients than stirring or whisking.


You have a contamination. Your basic inks are just fine in their individual cans. The problem is when they touch something new.
Rubber base inks hate oil. I think that is your problem.
You are trying to be green and not use solvents. Crisco and soaps are probably your problem. Don’t worry about the environment. Use a bit is mineral spirits paint thinner.
I am used to old inks that are pretty stiff. Your ink looks pretty thin. Is it fresh straight from the can? You can put it in a jar if you wish - if the jar is free from any residue. I put my mixed ink in baggies.

Inky is onto something - That looks very very thin, almost like paint or something.

I agree with the last two posts…you have a contamination for sure. I use the same inks (von Son rubber) exclusively, and I don’t think I could create bubbles if I tried. I highly recommend California Wash as a cleaning solvent. Mineral Spirits should be good as well, but don’t let dawn or simple green near your inks or press.