The problem with water soluble oils

"Peonies in Crystal" -36 x 36"
This is my newest painting
and it has nothing whatsoever to do with the topic
of water soluble oils

I teach a lot of painters each year and, increasingly, I see them bring water mixable oils to my classes.  Their rationale is understandable: they want to avoid exposure to dangerous chemicals and think that the AP non toxic classification on the label means that these paints are globally harmless.

It doesn't.

"A product can be certified nontoxic only if it contains no materials in sufficient quantities to be toxic or injurious to humans, or to cause acute or chronic health problems".

The focus of that designation is us.

AP non toxic doesn't consider the plants, animals, and microorganisms that will be exposed to our pigment if we put it down the sink or in landfill where it will eventually break down and enter the watershed
Checking out the online MSDS sheets posted by every paint manufacturer will tell you a different story.  Under environmental or aquatic toxicity, you'll find phrases like: "no data available" or "unclear".

Water mixable oils are, in fact, exactly the same as regular oils: they're made of the same dangerous pigments suspended in harmless vegetable oils, but they have an added emulsifier that allows you to clean your brushes with soap and water.  This nifty development means that painters are washing hazardous waste down the drain.

Like the painters who use traditional oil paints, WM oil painters should be capturing the sludge from their brush cleaning and disposing of it at hazardous waste facilities.

Don't stop reading in despair and don't stop painting.  This is not added work and complexity; it's actually easy!

To save your paint sludge, you just have to clean your brushes in a bucket of water instead of under running water in the sink.  Put a grid (like these) at the bottom of the bucket so that pigment falls through and, when you have a layer of pigment collected under the grid, let the water sit for a day until the sludge settles to the bottom.  Decant the clear water off the top for reuse, and scrape the pigment sludge into a separate, lidded container.

When this pigment container is full, label it as "Paint sludge, contains heavy metals/ cadmium" and bring it to your community's chemical collection site.  In my city, landfills and some fire halls accept chemicals.

Easy peasy!

**I detailed the same process for traditional oil painters to reclaim pigment from solvent a few years ago in this blog entry.

FYI: acrylic painters must do the same thing.  They use exactly the same toxic roster of pigments that oil painters use, and their paint water shouldn't go down the drain.

Golden Acrylics has information about capturing pigment from brush cleaning water here.  It requires 2 garden amendments that you can buy at hardware or garden stores which, when combined, will solidify the pigment so that you can save it for safe disposal.

So what do I think of water mixable oils, overall?

Given that neither should be put down the drain or in household garbage, I'd choose to use traditional  rather than water mixable oils.  WM oils have a sticky texture that's unpleasant to work with and I don't see any advantage to using them.

If you want to avoid inhaling solvents when you clean your brushes, you can clean in vegetable oil.  Just make sure to collect and dispose of that oil as hazardous waste.

It's my hope that this information reaches a lot of painters.  Please forward it to your painting buddies and let's all work with the long-term health of ourselves and the planet in mind.

Happy painting!  Really!


Cindy said…
Thanks for this Ingrid. I have used the filtering system you mentioned for acrylics (lime and aluminum sulphate) and all the paint is filtered leaving clear water. It works well and I can sleep at night :)
Cindy Bouwers
I'm so happy to hear from painters who are working responsibly, Cindy. It can be rather gloomy to contemplate our environmental impact so people like you make my day!

Happy painting!
Thanks for this post Ingrid. I do exactly that with my oils, but had never seen the information on acrylic water disposal. Love, love, love your peonies!!
Thanks, Sharon! These peonies were a journey!

I hope you'll spread the word about safe disposal to painters that you know.

Happy painting!
Les Gray said…
Big changes have taken place with W-S oils. I tried them twice over the past decade, and was disappointed. I recently brought two stray cats into the studio and decided to try them once more. On-line videos taught me I was using them wrong. Too much water in mixing. The brands have all improved. The biggest break-through was using Royal Talens "Cobra" brand water mixable oils. Briefly it is best to not mix water to thin most brands, use painting mediums to thin the paint. Who would have guessed.. With Cobra brand I can use water mixed with a little medium for thin washes. (they have several tutorials on-line that were very useful) Cobra oils are nearly the same feel as regular oils on the brush and canvas. My biggest thrill is clean-up. Brushes and palette clean so easy. Disposal is the same with any paint. (As an alternative Gamblin makes non-toxic painting mediums. I would say it reduces toxins but not to zero). Still prefer Cobra brand.
I feel this over-all use of W-S oils is so easy to use, and so much better in the studio for me and my two little friends who now share my studio. I have learned to use them properly and enjoy them just as much as the linseed based oils. I have been told mothers whose studio is in the home have found them to be oder free, and safer also. (by the way, I am not associated with Royal Talens) Just a guy who paints.
Hi Les,

I've never tried Cobra brand. It's interesting to read about your experience with them.
Thanks for sharing the information!

Happy painting!