The smell of turpentine used to be inseparable from oil painting. For studio work, ventilation makes solvent use manageable. Outdoors, you'd think the open air solves the problem entirely — but carrying flammable solvents on a hike, spilling them on natural ground, and breathing fumes while you paint in the sun creates a different set of issues.
A growing number of plein air painters have moved to solvent-minimal or completely solvent-free workflows, for entirely practical reasons. Less weight, fewer leakage risks, simpler cleanup, and paint that behaves more predictably in the field.
Why Solvent Is Less Necessary Than You Think
Solvent does two things in traditional oil painting: it thins paint for the initial lay-in, and it cleans brushes between color changes. Both of these can be accomplished with alternatives that work just as well outdoors.
For thinning, a painting medium like linseed oil, walnut oil, or a commercial alkyd medium serves the same purpose without the evaporation and toxicity issues. The paint handles slightly differently — it stays wetter longer and has a smoother feel — but most painters adapt within a session or two.
For cleaning, oil itself is the most effective brush cleaner. A brush swirled in walnut oil or safflower oil releases pigment just as effectively as one swirled in mineral spirits. The difference is that oil doesn't evaporate, doesn't smell, and doesn't damage your skin.
The Solvent-Free Brush Cleaning Method
Quick answer: Dip your brush in walnut oil, wipe firmly on a rag, and repeat two or three times. The brush is clean enough for the next color. A proper oil-then-soap cleaning at home returns brushes to new condition.
This is the core technique that makes the whole workflow possible:
Keep a small container of walnut oil or safflower oil on your pochade box rack. When you need to switch colors, dip your brush in the oil and wipe it firmly on a rag or paper towel. Repeat two or three times until the color stops transferring to the towel. The brush is now clean enough for the next color.
For a deeper clean between major color shifts — say, moving from a dark passage to a light sky, use two wipes: first in the oil, then on a dry section of your rag. You won't get the brush perfectly pristine, but you'll get it clean enough that the residual color doesn't contaminate your next mix.
At the end of the session, a proper oil-then-soap cleaning in the studio returns your brushes to new condition. The small amount of walnut oil left in the bristles actually conditions them between sessions.
Choosing the Right Medium
Your painting medium replaces solvent for thinning and can also serve as your brush cleaning oil, simplifying your kit further.
Walnut oil is the most popular choice for solvent-free plein air work. It dries slower than linseed oil, giving you more open time outdoors — useful when sun and wind are already accelerating dry time. It doesn't yellow, it's food-grade safe, and it doubles as your brush cleaning medium.
Linseed oil dries faster than walnut oil and creates a tougher film. Good if you're painting in cool or humid conditions where slow drying would be a problem. The trade-off is less working time on the palette.
Alkyd mediums (like Liquin or Galkyd) accelerate drying significantly. Useful if you want touch-dry paintings by the next day, but they reduce open time on the palette, which can be challenging in hot or windy conditions.
For most plein air situations, walnut oil strikes the best balance between working time, safety, and versatility.
Palette Management Without Solvent
Without solvent to strip your palette clean between mixtures, you need a slightly different approach to palette management.
Squeeze out clean piles of paint along the edge of your palette at the start of each session. Mix in the center area, pulling from the clean piles as needed. When the mixing area gets crowded or muddy, scrape it clean with a palette knife before continuing. The scraped paint goes onto a rag or paper towel — not back into the clean piles.
An aluminum palette makes this easier than a wooden one. Paint scrapes off aluminum cleanly with a palette knife, and the surface can be wiped with oil and a rag for a fresh start without solvent. The Walnut Art Easel Box includes a flexible aluminum palette that can be lifted out for hand-held mixing or placed flat , both useful for managing a solvent-free workflow.
Keeping Paint Workable in the Field
One of solvent's hidden benefits is that it evaporates, keeping the paint surface from skinning over during a session. Without solvent, oil paint exposed to sun and wind can develop a skin faster than you'd like.
Squeeze out paint in slightly larger piles than you normally would. The center of a generous pile stays wet even when the edges begin to set up. You lose a little paint to waste, but you gain uninterrupted working time.
If your pochade box has a rubber-sealed lid, you can close it during breaks — even a fifteen-minute lunch — and the sealed environment slows the oxidation process. Some painters report keeping palette paint workable overnight this way, allowing them to continue the next morning without remixing.
On extremely hot days, move your palette into shade if possible. Direct sun on a metal palette creates surface temperatures well above air temperature, and hot oil paint becomes runny and unpredictable.
Simplifying Your Field Kit
Quick answer: Remove solvent containers and secondary brush washers from your kit. Add one 2-oz bottle of walnut oil and extra paper towels. The net result is lighter weight, less spill risk, and no flammable materials.
A solvent-free workflow naturally reduces what you carry. Here's what changes:
Remove from your kit: solvent container, secondary brush washer for solvent, disposal rags soaked in turpentine (fire hazard).
Add to your kit: one small container of walnut oil (2 oz is plenty for a full day), extra paper towels or rags for wiping.
The net result is lighter weight, less spill risk, and no flammable materials in your pack. For painters who hike to remote spots, this simplification is meaningful — both for weight and for environmental responsibility.
The Transition Period
If you're switching from a solvent-based workflow, expect a short adjustment period. The first session or two will feel different — brushes don't get as clinically clean, paint mixes feel oilier, and your instinct will be to reach for the turpentine jar that isn't there.
By the third session, the new workflow becomes automatic. Most painters who make the switch report that they don't miss solvent at all, and some say their color mixing actually improved because they stopped over-thinning their paint with spirits.
The quality of the paintings doesn't change. What changes is the experience of making them — less chemical exposure, simpler logistics, and a process that feels more aligned with what drew you to painting outdoors in the first place.
Have you tried a solvent-free workflow? Share your experience and favorite alternatives in the comments.
Frequently Asked Questions
Can you oil paint outdoors without solvents?
Yes. Walnut oil or safflower oil replaces solvent for both thinning paint and cleaning brushes. Dip your brush in oil, wipe firmly on a rag, and repeat two or three times. Most painters who make the switch report that they don't miss solvent and that their color mixing actually improves.
What is the best painting medium for solvent-free plein air work?
Walnut oil is the most popular choice. It dries slower than linseed oil (giving you more open time outdoors), doesn't yellow, is food-grade safe, and doubles as your brush cleaning medium. One 2-ounce bottle serves both purposes for a full day of painting.
How do I clean oil paint brushes without turpentine?
Swirl the brush in a small container of walnut oil, then wipe firmly on a rag or paper towel. Repeat two or three times until the color stops transferring. At the end of the session, a proper oil-then-soap cleaning at home returns brushes to new condition. The residual walnut oil actually conditions the bristles between sessions.
