Cuni water soluble encaustics – initial review

What an interesting paint! I ordered these from Custom Encaustics here in Tucson; they seem to have just arrived in the U.S.

According to Cuni, “The content of our tubes is basically an emulsion of beeswax and potassium soap with pigments.”  I have found a few recipes for wax soap paint (see theModot cookbook and D. B. Clemons) based on borax or ammonium carbonate as the alkali, but Cuni and others say these are brittle, with some handling problems. I’ll do another post on what I’ve found out about potassium soaps, etc.

I purchased the medium, the retarder, and a few tubes of paint, figuring that I would mostly mix my own pigments into the medium. Color choice in the Cuni line is somewhat limited now; many of my favorite pigments are missing. (The line will expand soon, I understand.)  I have never used encaustics, so my take on these is from an oil and water media painter’s viewpoint. Some initial observations:

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Oils used in paint brands

I am becoming aware of the problems of very slow-drying oil paints, so it’s worth knowing what oil binder is used in commercial brands. I have found reasonably good info on these paints. Whites excluded.

Gamblin – linseed, some safflower
Grumbacher- linseed
Richeson Shiva – linseed except lightest colors
Maimeri Puro – poppy, safflower
M. Graham – walnut
Blue Ridge – linseed and walnut combo
Sennelier – safflower
Lefranc and Bourgeois – safflower
Mussini – Damar/linseed
Daniel Smith – linseed?
Rembrandt – as of 2008, linseed (but mine sure dry slowly)
Williamsburg – was linseed, some safflower introduced by Golden
Blockx – poppy except for mars, earths and blacks in linseed
Winsor Newton – mostly linseed
M. Harding – linseed
Vasari – linseed

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Some alkyd info

I bought some Gamblin solvent-free gel and have been testing it out. It seems to dry in the 3-4 day range. I used to paint a bit with Griffin alkyds and liked them, but I started to avoid alkyd products when I became intolerant of solvents. Almost all alkyd products have solvent in them, Gamblin gel and M.Graham walnut alkyd medium being the exceptions. I wasn’t sure why until I got in touch with Gamblin, asking if they saw any problems with grinding pigments directly into their solvent-free gel to speed drying of some slow pigments.

The Gamblin rep told me it should make a workable paint, though much slower drying than tubed alkyds, and not necessarily having the big alkyd advantages of consistent drying time and even sheen. He said that alkyd resin is generally much too dense to make tubed paints without solvents. From that I would guess that the gel must overcome this with a high percentage of safflower oil compared to mediums like galkyd, diminishing the alkyd characteristics somewhat. I have started a yellowing test and will see how it does.  M. Graham’s walnut alkyd medium has a reputation for yellowing, but lightening again with exposure to light.

I made some quick tests with fast- and slow-drying pigments and was encouraged by the drying rates and sheen. They all dried in 3-4 days  and had an  even semi-matte sheen. A paint that reliably dried in 3-4 days across colors might have some value, or I might mix up just the very slow dryers this way and try it mixed with oil paints. Gamblin says it would be okay to use this on top of a lean oil underpainting or egg tempera.

Gamblin’s suggestion for using the gel for slower drying paints is to lay out the oil paint on paper towels to leach the oil, then add the gel.

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Fat over lean, trying to calm down…

I am trying to get some perspective about the pitfalls of oil painting. Nothing can make you quite so frantic as reading about fat over lean. All our paintings should be falling apart if it is really that dire, since we use paints with lots of additives and know little about their oil content. As far as I know this is not happening en masse. So here are my current conclusions:  

1. A respected figure in art materials, George Hanlon of Natural Pigments, advises: “The fat-over-lean rule is not an effective one because it is not well understood and is often misinterpreted or misused. A simpler approach to the issue of constructing sound paintings is to determine the hardness of paint underlayers. If 1) the underlying paint layers have sufficiently dried, usually “dry-hard,” and 2) the underlying paint layer has not formed a film that is “closed” (no absorbency or penetration from upper layers), then one could paint over it without having to calculate the paint binder to solid particle ratio of the paint…”  (See thread, also here.)

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Zinc white and oil paint

Another pitfall for oils… zinc white is a problematic pigment, possible causing adherence issues with acrylic grounds on canvas. That’s okay, because I don’t have zinc white….   Well, turns out that almost all whites labelled titanium white have zinc in them, supposedly under a voluntary 15% limit but no one is saying for sure, and nobody knows for sure if that limit is really safe.  I found a grand total of 3 whites without it that meet my requirements of not being ground in linseed oil, which yellows a bit too much for a white, or safflower oil, which may also be problematic, and not containing lead. I limited my search to the 10 or so brands I regularly buy, so there should be a few others, but very very few overall.

  • Blockx titanium white, poppyseed oil
  • Holbein ceramic white (not titanium, a bit experimental which strikes me as a bad idea since zinc was a bit experimental too), poppyseed oil
  • Holbein titanium white, poppyseed oil
  • Update: Blue Ridge makes a pure titanium white in linseed/walnut oil. Also see Michael Harding.

That’s it.  I have two giant tubes of titanium white with zinc that I will try to limit to panels only, which should be safe…  I’m getting closer and closer to mixing some of my own colors. I’m so tired of finding these things out after years of painting and hundreds of dollars.

I found an interesting note on eggtempera.com. Someone asked onebof the zinc researchers if it is a problem in egg tempera. He said it should be okay in egg tempera or casein, but not alkyd. Sounds like the interaction with oil is the problem.

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Oil paint drying tests

I wasn’t too scientific about this, since I only thought about looking into drying rates after the strips were painted, but I did make notes of the fastest and worst driers.

This was eye-opening. Based on this, I would mainly eliminate brands without linseed oil for indirect painting, except for the very last layers.   I have probably thrown away a lot of money not knowing what I am doing.  I wouldn’t buy any of the slow driers anymore in non-linseed binders; they have to be protected for weeks. Safflower oil is sneaking into a lot of lines; be wary. Sometimes I wish I was more of an alla prima painter, or that I could stand acrylics!

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Fat over lean in oil painting, via Gottsegen

Gottsegen offers charts of the oil absorption and drying rate of pigments. There are fights on the internet about whether leanness (oil content) or drying rate are most signifcant in the fat over lean principle. My reading is that the real issue is oil content (ie you could use a low oil content/slow drier in an underpainting if you wait to let it dry before overpainting), but oil content is harder to evaluate so drying rate is a stand-in.  They are not always line up, though.  Gottsegen’s info at least lets you make an informed decision if you want to follow one or both. A good conservator’s viewpoint is found at Sanders Studio.

Of course this assumes you are not using a paint that is engineered to over-ride these distinctions with driers and stabilizers. Paint manufacturers may offer their own lists, which would supercede this, and in practice they can differ quite a bit from Gottsegen. Sennelier for instance uses safflower oil, M. Graham uses walnut oil, and Blockx mostly uses poppyseed oil, which will dry slower than linseed oil. M. Harding has excellent info on oil content and drying rate for their pigments. Another general pigment list with good info is at Sanders Studio. M. Graham has drying rates but not oil content.   

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Is oil painting a dying art?

My husband laughs immoderately when I try to discuss archival issues about painting media, and tells me that I am pursuing a dying art. He is a violinist, but also a techno-nerd; definitely the first on our block to try 3d printing. In music he thinks he is seeing the dying of classical music as a living tradition, and he gives me some good reasons to think this may soon happen with physical paint as we know it. I spent most of my work life with digital art, then returned to physical media at retirement. One of the oddest cognitive effects of this transition is the automatic reach for the undo button, with the weird effect of a missing limb. I laughed and it finally faded, but the truth is that the future of painting probably includes the undo button much more than my tubes of paint.  

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