Oils with Cuni encaustics, and some water mixable oil review info (Cobra and Artisan)

In my explorations of Cuni encaustics, I have come to the conclusion that it is difficult and time-consuming for me to handle large gradations, such as on a floor or wall in a scene, with much control.  I have too much trouble with lifting while trying to get even paint. (It is possible to get a fascinating translucent texture by rubbing thick Cuni paint, layer after layer, but this is a slow technique for large areas.) On the other hand, the paint excels at detailed textured subjects and highlights. I thought I would try a mixed layered technique: underpainting in oils, glazing the shadows and working flat areas with oils, and painting the light textured areas with Cuni encaustics. (Jorge Cuni tells me it should be quite sound to paint the encaustics over dried oil paint, and vice versa.)  The overall approach worked very well, and I will continue to pursue it, but I tried Cobra water mixable oils and found them a mixed bag for this approach. (I can’t tolerate solvents, making WMOs a good option for some things, which is why I tested them out.)

In a comparison test I did with Holbein Duo Aqua and Daniel Smith, I thought Talens Cobra WMOs came out well. They are less expensive, combine as well with water as Duo Aquas (both are a bit better than Daniel Smith), and are more fluid than Duo Aquas, a trait I usually prefer. (Daniel Smith are also more fluid.)  Many people prefer Duo Aquas, and I do think they handle well, but I found to my surprise that I dislike the earths. They seem greasy and unpleasant, with some filler material.  I decided to invest in a bigger palette of Cobras and the two mediums and painting paste.

I have since done two underpaintings in Cobra for the mixed indirect process. I am finding myself very disappointed in using it for underpainting, and overall I am frustrated with its fragility until it dries hard, a slow process. The paint seemed a bit too oily for a first layer, and it took 4-5 days for an umber or gray grisaille to dry, vs. one day for traditional oils. I have read that water mixable oils have to be engineered to dry slowly, so the water will evaporate fully before the paint skin seals. This makes them pretty undesirable for underpainting! The Cobra painting medium contains some alkyd, but it only accelerates drying a little. Perhaps I should look again at the Holbein Duo Aquas; they also dry more slowly than traditional oils in grisaille, but quite a bit faster than Cobras.   All in all, for underpainting, I think regular oils are better for me, since I don’t like alkyd mediums indoors.

On the other hand, glazes done with Cobra paints worked pretty well. The oily quality of the Cobra paints is not a problem for glazing.  I think for this type of painting, the best approach for me may be to underpaint with traditional oils, glaze shadows and paint broad passages with WMOs,  and highlight and texture with Cuni encaustics. Because of water cleanup, I can quickly move back and forth between the encaustics and WMOs as needed, which is very useful. While few people will be trying this combo, I think anyone who uses WMOs for indirect painting may want to consider oil underpainting, or fast-drying mediums (which may contain solvents, see below).

A few notes on the Cobras:

Cobra Colors

Cobra has done a good job with their selection of single pigment paints.  In the yellows,  Permanent Lemon Yellow, PY184, is a good cadmium lemon substitute. Transparent yellow medium, Py128, is often mentioned as an aureolin substitute. Permanent yellow medium, py154, is a very good neutral to warm yellow.  I didn’t get the Indian yellow, Py110, figuring I could mix it myself with an aqua dispersion I have. Po43, perinone orange, turns out to be very similar to Pyrrole Orange (po73), a blazing vermillion orange, though probably not as lightfast.  In the reds, I got the very useful Pyrrole red, pr254, and Madder lake, pr264, which is a pretty good alizarin substitute, though the Cobra version is not as dark as some.  Primary magenta is a pv19 that is closer to the quinacridone rose shade of pv19 than the deeper quinacridone violet.  I didn’t buy a purple.  The rest of the palette is pretty standard with ultramarine blue, phthalos, and a nice chromium oxide green. In the earths, I got the two transparent oxides, which are both very nice. The transparent oxide red is the wonderful shade of pr101 often used as a burnt sienna substitute. Yellow ochre is a bright, clean, slightly orange version. In tints it behaves a lot like the naples yellow hue made of pbr24. Raw umber is a mix, not pbr7, and is a bit more transparent than usual. With white it makes a near neutral tint, slightly warm and greenish.   If they were to add a few colors, I would like to see the darker pv19 (quinacridone violet), pyrrole orange since I think it is more lightfast than perinone orange, and perylene maroon to mix blacks. But all in all, Cobra has made a good selection, using solid lightfast substitutes for toxic pigments.

I think Cobra overall has a better approach than Holbein (or Artisan) to pigments. A lot of the Duo Aquas are overly complex mixtures that include some questionable pigments, like Naphthols and Hansa yellows. Pigments can easily be checked on the Dick Blick site by clicking the item number, then “pigment info”.  Buyer beware!

I have been making some colors with the Cobra painting paste and aqua dispersions. Because of the water in the dispersion, the result is fairly thin and tends a bit toward the stickiness of WMO mixes, but for me it is quite workable. I haven’t found anything on the web about this, but I believe it should be completely sound from what they say about the paste. Dispersions are much easier and safer than using powdered pigments; it’s a nice feature that they can be used with WMOs. I don’t find that paint made this way mixes with water as easily as Cobra’s paints do, but that is not a big problem. I have also run one test making paint with the painting medium, and a mix of the paste and painting medium. This also worked well, and speeds up drying a bit.


There are a few videos on Youtube that give some info about the mediums.

1. The painting medium has alkyd in it in addition to an oil, but remains mixable with water.  The alkyd seems to speed up drying time moderately, although Talens claims it doesn’t.  (Actually, my results on this have been mixed; if I use a lot of medium it may dry slower.) The medium makes paint much glossier.  I played around with their suggestion to pre-mix the medium with water for customized behavior.  A 1:1 mix with painting medium and water seems more workable than pure water for an initial wash.

There are a lot of mediums in different WMO brands that include alkyd resin for fast drying. I wonder how this affects the problem of letting water evaporate before the paint skins over. Is this a trade-off of strengthening the paint with alkyd vs. weakening it with trapped water?  That would make me disinclined to add water when using alkyd mediums. Some brands include petroleum distillates and other hazards in the alkyd mediums — Duo Aqua and Winsor Newton per MSDS sheets on Dick Blick.  That seems a bit unfair to artists who are mainly using the paint because of solvent intolerance.  The Cobra painting medium does not list hazardous ingredients; on the other hand it probably doesn’t speed drying nearly as much. Gamblin told me that the way to thin alkyd resin if you don’t use solvents is to add more oil, so solvent-free alkyd mediums dry a lot more slowly.

2. Glazing medium is fatter than painting medium. It doesn’t include alkyd and appears to be mostly oil (quite fat). I also tried a 1:1 mix with the glazing medium and water. It dulls the glossy depth of glazes a bit, and gets tacky over time, but is useful for multi-layered glazing to keep a fat-to-lean spectrum.  One of their videos gives ideas about a sequence of mediums for good fat-to-lean practice:

1. Pure water
2. Painting medium and water
3. Painting medium
4. Glazing medium and water (they say a 1:1 mix is still fatter than pure painting medium)
5. Glazing medium.

Talens says these mediums don’t affect drying time, but that doesn’t seem true in my limited tests. I find the glazing medium dries more slowy and the painting medium faster than pure paint.

WMOs and Water

As many people have noted, the paint gets more matte and tacky (or sticky or gummy, if the observer dislikes the effect), when mixed with water and allowed to sit a bit.  Water also lightens the paint until it evaporates, which makes color control more difficult; use of WMO mediums with water improves this.  Many people recommend against using any water except to clean up.  This is because WMOs contain emulsifying agents, but do not form an emulsion until water is added, so they handle most like traditional oils when water is excluded.  Once they become an emulsion, they behave differently.

It’s useful for artists to understand and play around with emulsions, since they can be quite interesting. Artists often consider the behavior of WMOs with water a defect, but it can be useful for specific techniques. As soon as water begins to evaporate, it causes the paint to become tacky and resist motion, or seize, as it is sometimes described.  This affects the paint even after the water has evaporated, leaving it much less mobile though still wet.  It then lends itself much more to broken color, wet-on-wet layering, and drybrushing, in the manner of some tempera paints and emulsions like tempera grassa. With practice, it makes possible a kind of alla prima layering, a good technique in an artist’s toolbox. Spend some time on Tad Spurgeon’s website, and you will find he has many recipes to make oil paint seize for alla prima layering; there is evidence that old masters used emulsion properties for this purpose.

I think I am one of very few people who consider the tackiness of water/WMO mixes to be an intriguing feature; it’s because I like drybrush techniques and have spent time with a number of emulsion paints. To my surprise, of all the paints I have tried, Artisan is probably the best for seizing effects; perhaps that’s one reason many people like it least of all. Washes with water set up very quickly, and even slightly thicker areas set up within 10-15 minutes or so, enough for drybrushing of the next layer without much interaction. This is dependent on the absorbency of the surface and the pigment, so it takes some time to get a feel for how it works.  The biggest problem pigment is titanium white, which seems to stay wet a long time.  I have experimented with using Guerra transparent titanium white (a nanoparticle version a la sunscreen) made into a paint with Artisan painting medium (linseed might be better but it’s all I have). It sets up extremely fast and hard in comparison. Transparent titanium white deserves a post all its own.

Artisan also takes on a fairly even matte finish when mixed with water. Cobra, Duo Aqua and DS are a bit too oily for this to work well. (If you want to use thin washes with these paints, they will set faster and more evenly if you add some Cuni water-soluble encaustic medium, or to a lesser degree a paste made of calcium carbonate and lean medium, or methylcellulose. Of course, the brand mediums can be used also.)  Even with these additions, though, there are distracting sheen differences between thick and thin areas.  For a painter who uses WMOs with water and achieves many textural effects, see Charlie Hunter. He has a You Tube video demonstrating Cobra with water. I see that he recommends Artisans for his workshops.

To my surprise, I found (in limited tests) that the Artisan paints also have less color shift in water washes than the others.  Daniel Smith did pretty well, but I only have a few colors to try.  Using magenta, Cobras and Duo Aquas both lightened and became colder. Artisan lightened slightly, but shifted very little in temperature.  If you like the seizing effect of water but it bothers you that the paint lightens with water, you can add methylcellulose to WMOs without this happening; the paint still sets up more quickly but retains its color.

WMOs and Longevity

Conservation studies are just starting on water mixable paints.   I have no knowledge of whether long-term problems occur with the addition of water, but there are many long-tested emulsion paints that combine water and oil.   Egg tempera by itself is a water-oil emulsion.  Egg added to oil paint creates an oil-water emulsion; this is increasingly thought to be common in old master paintings.   Sometimes people note with horror that surfectants used in WMOs are basically soap. Potassium soap (ie castile soap) and beeswax are probably the ingredients in ancient encaustic paintings like the Fayum portraits. They have endured longer than any other realist paint medium.  We need more information, but the ingredients in WMOs are not necessarily cause for rejection until we know more (and paint manufacturers tell us more). I suspect from my limited experience that water soluble oil paint is more fragile than pure oil paint, as many emulsions are, and may need more protection to endure.