Not all water soluble oil paint tacks up when mixed with water. Most problems are with one brand only (Artisan) or when people don’t know that they need to add water slowly and in small increments. That being said, the main reason I use WMOs is that I can use water to clean my brushes while painting and add small amounts of water when needed to thin the paint.

You can, of course, use traditional oils without solvent, but many folks do not want to use 100% oil as a medium and prefer a medium that is only part oil.

Clean up can also be done with only soap and water for traditional oils, but is easier with WMOs.

Many schools and other organizations do not allow traditional oils – assuming incorrectly that painters will automatically be using solvents – but will allow WMOs.

So, yes, traditional oils can be used solvent free, but it is easier to do so with WMOs.

Hope this gives you some idea as to why some folks use WMOs.

Don

I have a good set of WMOs now (sampling several brands, as is my wont ) but I don’t anticipate switching over to WMOs full time, because I can be solvent free by cleaning my brushes with some oil, or, using Turpenoid Natural (non-toxic, non-solvent).

There is some advantage to cleaning brushes with water afterwards, but it wasn’t offset for me by the limited brands available as WMO. (I want Old Holland, Blockx, Blue Ridge paints to use too, but these are not WMO.) Mixing some non-WMO with WMO doesn’t seem to help with “cleanability” for me, I need to be all WMO for that. I have some WMO paints that are super nasty and tacky (W&N), what a waste of money. The other brands are better, but then I had to learn through trial and error not to use too much water, not to use the product’s fast dry medium (Lukas—awful stuff!) and so forth.

I can avoid all this trial and error and weirdness by just using Turpenoid Natural for cleaning my brushes, and continuing to use Blockx, Blue Ridge, and so forth. (Or just clean with walnut oil or linseed oil.)

But, a lot of people seem to work well with WMOs and aren’t having any complaints, so for them it’s a good deal. Everyone will have a different experience and it’s clear when you look at some of the paintings made with WMOs that the paint performs well for these artists.

Pure oil as a medium is recommended for Alla-Prima technique.
For layered technique 50/50 or Ron`s 70/30 percentage Linseed oil/OMS are unbeatable mediums anyway.

You can use any regular oil medium for WMO. And it can be compatible with acrylic too.

Turpenoid natural – it is just very highly refined petroleum based thing. A kind of OMS but more powerful. Recommended as a brush cleaner. Better to use in closed jar anyway. OMS has less odor and said to be better for oil mediums.
Very pure kerosenes..:D

Turp au naturale is also one of the best things I have found for softening brushes that are not adequately cleaned and become stiff near the ferrule. Saturate the brush and wrap in a plastic bag for a while or overnight, then wash it out with soap and water and it usually gets it nicely back in shape.
It also works very well for palette cleaning and miraculously will soften up paint if you should allow it to get too dry. Same thing saturate it, cover with plastic wrap, let it soak in for a good while, bam, comes right off.

DO NOT recommended to use as a part of paint medium by conservators:

“Weber claims Turpenoid Natural can be used as a thinner in oil paints in quantities “less than 25%” of the volume of a mixture, and that it should not be used in underpainting or in a wash on the support/ground before painting begins — the oily component could make a painting that does not dry properly.

We are skeptical of an artist’s controlling the addition of this solvent in the heat of the creative moment, and can recommend it only for the brush-cleaning portion of the use guide. If an artist must use a thinner in the earliest stages of an oil painting we recommend a minimal amount of odorless mineral spirits (OMS), which is distributed by many oil paint-making companies. Do not use regular mineral spirits, which contains aromatic solvents that are hazardous, and be sure to follow the ventilation recommendations on the label of the OMS. In fact, it is hardly necessary to use a solvent in oil painting.”

WMO is compatible with acrylic paints and, therefore, can be tinned (in theory) with regular acrylic mediums (which is always works much better than water when you are using acrylic paints).

As for brush cleaning – there are nothing to be trouble for most artists. Just everything works well – soap, sunflower oil, oil medium, OMS, Natural Turpenoides, Gum turpentine, kerosene, detergents, Nail varnish remover, acetone, nitrocellulose varnish solvent, toluene and paper towels.

Most popular cleaners here are Murphy’s Oil Soap, drying oil, and OMS. Some artist’s use citrus thinners.