This post is to help anyone having difficulty learning to live without solvents. Technically water is a solvent, but I am using the term "solvent" to denote smelly toxic liquids. When you don't use odiferous materials, you might think you miss out on resin based mediums and quick drying alkyds. I was reluctant to make this change because I didn't fully understand what the options are. It turns out there are many, and with a little research, you can just about do everything that you could with traditional oils. After mining the WetCanvas technical forum and Blick's product pages, and much experimentation, I don't get sick from painting any more, and I can do just about everything I did before. I am sharing what I have learned.
I am aware of Gamblin solvent free mediums, M Graham walnut oil, the fact that many people clean brushes in oil, and that some people never clean brushes, but those are not the topic of this discussion. This is about approximating the traditional oil painting experience by including water. I am also aware that some people have a problem with water mixable oils in general, but those people are free to stop reading. Some people believe that it is unnatural to mix oil and water in painting, but people have been doing it for centuries using eggs, and it is prevalent in industry as well. I, myself, was biased against WM oils until I started getting sick from fumes.
I only describe products I have personal experience with.
Odors
Some of the brands smell like traditional oil paint, but some have a strong odor, like Lukas and Artisan. I managed to get hold of a previous generation tube of Berlin and it absolutely reeks. Even though they've toned it down in the reformulation, it's still quite strong. However, Berlin paints are extremely highly pigmented, some as good as artist grade, despite being a student line, and they have the same luxurious texture as 1862. With the exception of yellows, their hues are very close approximations too. If you can stand the smell, these are extremely good paints and an unbelievable value. Perhaps it is coincidental, but the brands I have that smell are only offered in student grade.
Lukas linseed oil smells just like regular oil, but Holbein oil has a very slight chemical smell. Artisan thinner has a weak ammonia-ish smell. Holbein brush cleaner smells like Formula 409 without the perfume (same active agent). None, I repeat NONE, of these, including Berlin paints, smell as bad as solvents. Most of the smells are weak and disperse quickly, and none are as strong as those of household cleaning products.
The smelly items are those that contain resins. Most brown mediums contain some kind of synthetic resin that has to be dissolved in something before it is added to the oil. This can stink pretty bad. The worst I have is MAX quick dry, but any medium with this ingredient will smell. Most don't smell as strongly as MAX, but MAX gets the paint dry really fast. It is entirely possible to paint without any of these smelly products.
Water is just as good a solvent as mineral spirits.
There are people on Wetcanvas who swear that certain brands don't mix well with water but I have not found this to be true. Some brands mix better with water, but I have at least one tube of every major brand, and every one thins with water. I read on Wetcanvas that Grumbacher relies more on hydrophillic oil than surfactants for miscibility, and I can say that their paints thin and rinse great in water. Their linseed oil is expensive, at $6 for 2.5 ounces. Artisan used to be problematic, but I believe they changed their formulation before I got my tube because it does thin with water but not as readily as other brands. Most reports I've read of the previous formulation say they're stiff and gummy. Webers accept water better than Artisan but don't rinse in water much at all. Berlins have excellent water mixability but they don't rinse all that well, possibly due to their beeswax content. Cobra and Daniel Smith are somewhere in the middle. Holbein gets the most praise for being the best brand, but I have found that Grumbacher MAX performs very well and is far more reasonably priced. I read on Wetcanvas that Holbein relies on surfactant rather than hydrophillic oil and I believe it because I have seen a rainbow soap bubble in the neck of my bottle of linseed oil. Wetcanvas reports are speculation based on technical releases, email responses from manufacturers and patent applications, because the companies themselves do not disclose how the paint is made. There is a video buried in Jerry's Artarama youtube channel that says Lukas oil has been modified at the molecular level. I haven't been able to verify it.
It is best to add the water a little at a time rather than all at once. Upon first contact with water, the paint turns milky, but if you keep mixing, this milkiness usually goes away. If it doesn't it'll be gone once the water has evaporated. The resulting thin paint acts just like paint thinned with solvent. The water evaporates quickly leaving only oil behind. Some people report that water thinned paint turns gummy, but I have only experienced thin oily paint. Some is oilier than others, but it all acts like oil paint. If the paint is heavily thinned, the paint film will be dull and matte because the water leaves tiny holes behind when it evaporates.
Mediums
This subject is a can of worms. For the most part I like to paint without mediums, but there are still options. Here is a list of mediums that I have used.
A good basic medium is 1:1 linseed oil and water. I have only done this with Lukas brand linseed but it mixes well and makes a slippery thin medium.
Lukas makes a quick dry medium that looks and feels like white water. The only information on the bottle says that it makes paint "meager" which I interpret as "lean". I just happened to read a very old post on Wetcanvas that says how it is supposed to be used. Mix a drop or two into the paint pile. It will get a little sticky after this, so add some water or medium. It will go on slick now. It doesn't thin your paint a whole lot because only a little is needed. For better or worse, a thin layer of paint will start to tack up within minutes, even with a stand oil medium. Before I read this I had been adding it to the paint by dipping my brush into the medium and mixing it every brush load. This puts way too much in the paint and it gets sticky and won't spread, and is actually slower drying. The nice thing about this medium is that it won't go bad in the bottle during storage. I've had mine a couple of years and the color and consistency haven't changed.
Lukas and a couple of other brands make a stand oil. I have some Lukas but don't use it because stand takes so long to dry. It smells like Berlin paint but not as strong. It mixes well with Artisan thinner.
As mentioned earlier, there are quick drying mediums containing resins. MAX dries fastest and claims to be able to be mixed with paint in any proportion. It dries tacky at first and hardens after several weeks. The final product appears to be very sturdy. It should not be mixed with water, but appears to mix with water thinned paint. Daniel Smith makes a similar product which can be thinned with water. It is less brown and less smelly but dries slower. They offer almost no information about it on their website. They also make a fast drying linseed oil but I haven't used it. MAX is very brown and will tint your painting if used as a barrier layer. Holbein makes a quick drying liquid medium that claims to make the paint tack up within 30 minutes. I haven't verified this but I can verify that their quick drying matte paste makes the paint dry about as fast. The gloss version is less slick than matte and dried slow for me. The matte one has almost no smell so may not contain resins. They have a nice stiff texture that doesn't dilute the color and they rinse well in water. Holbein says both the paste and liquid are safe to mix up to 50% with paint.
Cobra makes a painting medium and a glazing medium with no added driers. They do contain resins, so have a slight smell in the bottle. I didn't smell it at all when I mixed mediums with it. The painting medium is leaner than the glazing medium. The Cobra videos on youtube (produced by Jackson's I think) say that the painting medium contains 50% water, but if this were the case I would expect it to be milky in appearance and it is clear. I have read reports that the painting medium tacks up quickly but I did not find that to be the case. You can use both mediums the same way as a traditional damar/oil/turpentine medium by adding various proportions of water. It makes a similar resinous paint film. I add a drop of 1% manganese solution (see below) when I mix a small amount to speed drying. Cobra and Dan Smith make a painting paste that is basically colorless paint with no driers. Holbein makes a painting medium which is rumored to contain mineral spirits. I haven't verified this, and the possibility of it containing mineral spirits makes it unlikely I will buy any. Hopefully the Cobra doesn't contain mineral spirits, but like I said, it is clear instead of milky. In any case, I can't smell any.
Weber makes a water mixable version of Resngel which dries soft and rubbery where it has thick impasto texture. It has a quick drying rate. It has a slight resinous smell and thins and rinses reasonably well in water.
Update: This and all Weber's other WM products have been discontinued, along with Permalba paint.
If you make a medium with any of the above mixed with water, it is best to make it in small batches. Some of the products don't keep well mixed with water.
Finally, we can approximate a traditional thin resinous painting medium using unconventional ingredients. Some posters on Wetcanvas named "docpro" and "gigalot" modified Bill Martin's (another Wetcanvas regular) painting medium originally leaving in the spike oil, but I can't stand the smell, so I modified it to this:
1 part walnut oil
1 part water mixable linseed oil
1 part Artisan thinner
1/2 part Medium W (discussed later)
1/2 part Weber Synvar
Keep in mind that Synvar stinks because it contains mineral spirits, so this is low odor instead of no odor. Synvar for resin, Medium W for the walnut oil, walnut oil for slickness. It is very slow drying. Of course, without key ingredients like spike oil, it will not handle or dry as well as the original. We are still giving up things when we forfeit fumes. On the other hand, Synvar is more archival than natural resin. Everything in oil painting is a trade off.
Artisan thinner
The only company making a thinner specifically for water mixable paint is Winsor & Newton, probably because their original formulation didn't mix well with water. It
seems to work well with all the paints I own, although I have read reports to the contrary.
It is expensive, so I wouldn't recommend using it for cleaning brushes. I don't think it makes a great brush cleaner anyway, based on Wetcanvas posts.
Weber's website says wOil varnish can be used to thin paints but I don't have any. This may make a good replacement for the Synvar in my traditional painting medium.
Speeding drying
So it turns out that the drying speed (and dark color) of products like Galkyd and Liquin is not because of the alkyd, but because of added cobalt. That is good news for us, because driers can be added to any medium, and there are water miscible resin based mediums available to us. I had trouble with traditional alkyd mediums drying up in the bottle, so I'm happy to add the drier by droplets when I'm ready for it, rather than wasting an entire bottle of medium. There aren't any direct WM equivalents to Liquin, but you may be able to approximate this by adding fumed silica to a medium.
Commercial driers like cobalt and CoZiCa are dispersed in solvent, so if your medium contains water, these driers won't mix. You can make your own water soluble drier by buying a salt of cobalt, magnesium, or other metallic drier and dissolving weakly in water, say a 1% solution. A "salt" is "sulfate", or "SO4" after the metallic element. You can dispense this by dropper the same as the commercial driers, but be careful and do tests. You may have made it stronger than it needs to be.
Another alternative is to drop lead fishing weights into your linseed oil. Supposedly, some lead will leech into your oil but the amount is miniscule compared to real black oil. If the oil isn't changing color much, it isn't absorbing much lead. I tried this with straight linseed and a 1:1 mix of linseed/Gamsol. Only the linseed/OMS caused any oxidation of the lead and the solution turned orange. My straight linseed is still light yellow. A linseed/water mix would probably oxidize the lead quickly.
Drying time and stickiness
Keep in mind that I live in a hot humid climate with mild winters, so your results may vary.
In my experience with oil paint, there are occasions where it takes weeks to dry for no apparent reason. Water mixables are no different. Some people claim that they dry slightly faster than traditional oils, but I have found that on the whole, they dry slightly slower. They can be tacky for several weeks after drying to the touch, but will eventually lose the tackiness and feel like regular dried oil paint. Maybe this is the surfactants leaving the paint? Or more likely, it is the amount of humidity in the air.
Medium W
This is a miracle medium by Schmincke available in liquid and gel form that will make all the traditional paints you've already bought be water mixable. It really does work, but will dilute your color slightly. It's worth investing in if, like me, you already have a hundred tubes of traditional oil paint. It is also useful when a color you want doesn't come in a water mixable variety or if you don't want to pay Holbein's absurd prices.
There is a Lukas version of paint emulsifier, but I believe it contains no oil and has a strong smell. It is only available in 1 liter bottles, so I won't be trying it. I have read on Wetcanvas that it is inferior to Medium W. The oil and resin in Medium W keep it from overdiluting your paint. If the paint does get too weak with the gel, you can add a stiff paste medium for body and opacity.
Mixing with traditional oils
You can mix in any ratio, but as you increase the ratio of traditional oil, you lose the water miscibility. Same goes for traditional mediums. You are free to use Liquin, Galkyd, damar, or whatever with these oils, but that is defeating the purpose somewhat because they will need to be cleaned with solvent unless you are doing your final soap and water cleanup for the day.
Cleaning brushes
Yes, they absolutely will rinse out in water, although some brands rinse better. However, it doesn't take long for your water to turn oily if you rinse a lot. A good solution I have found is to fill a silicoil jar with a weak solution of water and dish soap for the wash, and a jar of clean water for a rinse. This gets practically all the pigment out of the brush.
If water is not abundant, you can preserve your rinse water by dipping the dirty brush in water and dabbing it on the palette to work paint out. Wipe the sludge off and repeat as necessary.
I have just gotten a bottle of Holbein brush cleaner. It feels and smells like thick Formula 409 but without the perfume. The instructions don't say at what concentration to use it. I think this would best be used added to water in the manner of my 2 tank method, but it is far more expensive than dish soap and dish soap already works fine. I've read that it cleans well but don't know if it's necessary. It might be good to take a small quantity on the go, if dish soap isn't practical.
Also, exposure to air will decrease water miscibility. Paint that has begun to oxidize loses its ability to be cleaned with water. If the paint is fast drying, this can happen on the palette overnight.
Making paint
Yes, you can make water mixable paint and gel mediums! It works exactly like making regular paint except you use WM linseed oil. Everything else is the same. I made some nice stiff oleogel using Lukas linseed. Keep in mind that beeswax will decrease water rinsability.
Paint made with Holbein oil seems to rinse out of the brush better than paint made with Lukas oil in plain water. Lukas oil is lighter in color.