Hand-mulling Paint, Part II

Continued from Hand-mulling Paint, Part I.

If you’re mulling a particular pigment for the first time, you won’t know just how much oil you should add. You can do some research online, something like “raw umber oil absorbtion” – but you don’t really need this information to begin. At first, use less oil than you think you will need. Many pigments (not all) will loosen and become more and more oily as you mull. I try to add just enough oil to pigment so that when I start mixing with a spatula, I’m pretty sure it won’t be enough oil. Then I start mulling. Often it winds up being enough after all. Once you’ve done this, you can keep notes on how much oil to add to each pigment.

You’ll go in a big circular motion with the muller, and pretty soon you’ll have to stop, grab the paint spatula, and scrape the paint together into a pile again. You’ll have to scrape paint off the sides of the muller as well. Make it into a pile and start mulling again. It helps to switch hands every so often. It can take a tiring amount of time with some pigments, and patience is sometimes required. After a while, you’ll know if you need to add more oil (or, sometimes, more pigment).

Below, I’m mulling and then scraping together a homemade copper green pigment into linseed oil:

Mulling Copper Green

Mulling Copper Green

Mulling Copper Green 2

Mulling Copper Green 2

Just how necessary is it to mull pigment? Why can’t you just mix the stuff up on the palette with a spatula and go? Well, sometimes this might work – the homemade candle black I made into an oil paint recently barely required mulling at all, and probably could have been used right after mixing it with oil – but other times, mulling is absolutely required. See the difference between mulling or not mulling Egyptian blue, below:

Mulling Egyptian Blue

Mulling Egyptian Blue

The first swatch is unmulled. It was quite difficult to even brush it out: I had to add extra oil and use one of my stiffer bristle brushes to manage it. The second swatch is after perhaps only two minutes of mulling. Big difference, isn’t it? The third swatch is the mulled Egyptian blue mixed with some zinc white. Nice color, huh?

Some earth pigments are said to display their best colors when only lightly mulled, and that this is one problem with the uniform grind of modern, industrially-produced pigments. I thought that I was seeing this phenomenon when I was grinding up a nice raw sienna from Sinopia Pigments. The more I mulled, the duller the color seemed to get. See the pic below, the difference between those two piles of paint? I thought I was seeing over-grinding in action. However, I was wrong: it was just that the finer clumps of pigment were soaking up more of the oil. When I added more oil back into the paint, its color sprang to life again. So if that happens to you, try the same.

Mulling Raw Sienna

Mulling Raw Sienna

I’ll post one more installment of the Hand-mulling Paint series, and discuss tubing your own mulled paint.


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4 Responses to “Hand-mulling Paint, Part II”

  1. Chrissy Says:

    Love the copper green! I have an obnoxious pile of pennies lying around – think I could use them to get this green? (how do you get them to go green on purpose?)

    • llawrence Says:

      Well, to make verdigris you’d dangle the copper over vinegar in a closed container. But modern pennies contain quite a lot of zinc as well, and maybe other stuff too. I’m not sure exactly what you’d wind up with. The copper green above is green bice: copper sulfate precipitated with washing soda. It’s more opaque than verdigris, and from what I understand more stable as well. It shifts color just a bit as it dries, then stops. Making traditional verdigris is something I plan to try at some point – of course!

  2. Mark Says:

    Heya, this is a good bit of info you have been kind enough to share. I am starting to get the itch to mull some of my own paint…perhaps I am even more excited about that then actually painting! It seems that there is not enough good/useful info “out there” on oil paints and their properties. I am not saying it impossible, but it took me a fair amount of search time to find that many commercial tube paints have excess oil separation due to too much oil being used in the manufacturing process.

    I wasn’t aware that with the inorganic/metal pigments that they will absorb a larger amount of oil while being milled then they will actually retain over their shelf life. I have taken to squeezing my paint onto a suitable paper…news print sketch paper seems to work well…to remove the excess and to better measure the amount of oil/medium I am actually using. Luckily I borrowed the Harold Speed book on materials and technique, which I now own. I learned more from that book then any of the later printed material I had read prior.

    I also find think it is awesome you have a liking for the toxic pigments of the past…much the same as my own. I am going to get around to doing a floral titled “Azaleas in toxic pigments” or something like that. I have a lead plate set above vinegar to produce my own silver white as well and will tryout your copper sulfate in due time.

    P.S. This is poor righteous peon from wetcanvas forum/lead lemon yellow thread. I am glad you had the links to your sites. I admire your work and I am certain your knowledge of paints will be a boon for me in times to come. Thanks and be merry!

    • llawrence Says:

      Hi prp! That was a nice find with the tube of lead chromate. Here’s a link for our readers:


      A note about the oil separation in the tube: I personally tend to think of oil separation as a sign of a healthy oil paint. Oil and pigment will separate in the tube if it sits for long enough – unless an excess of stearate or other additive has been used in the manufacturing. Paint makers should allow the tube to sit upright for a few days before shipping it off, to get rid of any genuine excess; but even if they don’t, it’s easy enough as you noted to do the same thing on our end.

      The Harold Speed is a volume I’ve been meaning to pick up for some time. Glad you got it.

      Best of luck with that lead white you’re making – that’s a pigment I have vague plans of trying to make someday (but not here at home!). I hope we will see the results when you’re finished.

      Thanks for stopping in and commenting!

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