I have done some outdoor painting with these paints. I quickly learned that if you use water as a solvent they seize up and get tacky quickly in the heat, so I use water only for brush washing outdoors. However, I have recently found a new use for them, as the oil paint component of a methylcellulose-oil emulsion, and for that type of painting, their ability to dissolve in water matters. I wanted to compare brands and see which is best for that, so I finally got around to making color charts of the water miscible oils I have: mostly Duo Aquas, about 6 Daniel Smith (DS), and 3 Cobra, plus a lot of Artisans that I didn’t test since I mostly have just not liked that brand, and it wasn’t at all reliable with water. I hoped to decide what brand to settle on, since it’s probably best practice to not mix them thanks to the proprietary chemistry.
I took a look at water solubility, pigment load, and handling as much as possible with small swatches.
Overall, Duo was very good, though I have two probably older tubes that barely dissolved at all, so the line may have improved. Cobra was similar overall, readily mixing with water. Daniel Smith was not as good. I had to fight to get it to mix, and it seemed to granulate or clump more in water. I also have a tube of Cobra Painting Paste; I mixed that with a pigment paste to make paint, which handled nicely, but didn’t dissolve in water well until I added a lot of the Cobra paste, making it kind of thin. Still, a nice option to have.
They all handled reasonably well straight out of the tube. Cobra and DS seemed a little looser and more oily, which I think I prefer for outdoor painting where these paints seem to get stiff on the palette much faster than traditional oils. The Duos are denser and hold brushstrokes in place better, but overall, they feel to me like something has been added to make them buttery and give them an even, slightly dull sheen. The worst of the Duos were the earth colors, which seem very dull and kind of unpleasantly greasy. Overall, pigment load was good in all brands with two exceptions: a quinacridone burnt orange from DS and quinacridone gold from Duo handled kind of poorly as pure color, seeming kind of mottled and thin. Dissolved with water and mixed with white they were fine, and I didn’t try them as glazes, which is probably their best use.
I was surprised to find that I didn’t like the handling qualities of Duo in comparison to the other two. This is probably mainly a personal preference related to the way I paint. [Update – using Cobra for underpainting, I found it too loose and oily and may revisit Duo for that. I also found the Cobras dried much more slowly than the Duos, in some colors at least.] I think for my needs I’ll try some more Cobras. I like the paint consistency, and it seems to work with water about as well as Duo. Cobra also offers the painting paste, providing an option to make paint and improve solubility. DS makes a transparent blender that may do the same, but Duo does not as far as I know. Cobra and DS are also far lower in price than Duo. Cobra has a good line of colors and single pigment paint; Daniel Smith’s seems to be expanding quickly but is not comparable at this time. For me, the winner is Cobra for now.