Your Brushes Are Fine. Your Drying Times Are Not.

You've been lied to about oil painting. The most repeated rule in the medium—'fat over lean'—is not a law of nature. It's a drying-time guideline, and if you follow it blindly you'll end up with a sticky, yellowed mess. I'll explain why in a minute. First, let's bust some myths and answer the questions you're actually asking.

But before that, a confession: I once ignored every drying rule in the book and painted a six-foot canvas in one weekend. It cracked within three months. Not a century. Three months. So when I say this stuff matters, I'm speaking from expensive experience.

Do you really need to follow 'fat over lean' in oil painting?

Yes, but not for the reason you think. The rule says each new layer should be more flexible and slower-drying than the one beneath it. That's not about some mystical property of oil—it's about oxidative polymerization. Oil paint doesn't dry by evaporation; it absorbs oxygen and cross-links into a solid film. If you put a fast-drying, brittle layer on top of a slow-drying, flexible one, the top layer cracks as the bottom moves. So the real rule is: slow-drying over fast-drying. That means your underpainting should use fast-drying pigments (like raw umber or lead white) and your final layers should use slower-drying ones (like cadmiums). If you ignore this, you'll get cracks within a year—not a century.

Here's the blunt advice: if you're painting alla prima (wet-into-wet in one session), 'fat over lean' is irrelevant. You're not layering. Stop worrying and just paint. The rule only matters when you build in distinct, dried layers. Winsor & Newton spells it out as 'fat over lean, thick over thin, slow-drying over fast-drying'—but they also assume you're working in layers. If you're not, ignore it.

Why do my oil paintings turn yellow and take forever to dry?

You're using too much oil and not enough solvent. Oil paint dries over one to three weeks or more—that's normal. But if you add extra linseed or walnut oil to make it 'flow,' you're slowing drying further and increasing yellowing. The fix: use a solvent like odorless mineral spirits for the first layers, and only add oil in the final layers. Or switch to alkyds, which dry in hours. And stop painting in a cold, humid room. Oxidation needs oxygen and moderate warmth.

Here's a number for you: if your studio is below 60°F (15°C), drying times can double. I learned that the hard way one winter. My studio hit 55°F and a painting that normally dried in four days took almost two weeks. So buy a thermometer. Seriously.

Can I use acrylics like oils?

No. Acrylics dry within minutes by water evaporation, not oxidation. That means you can't blend on the canvas the way you can with oils. You have two options: work fast and wet-into-wet with a retarder, or embrace the medium's strengths—crisp edges, layering, and glazing with acrylic mediums. Acrylics were developed in the late 1940s and popularized by Pop artists like Andy Warhol in the 1950s and 1960s. Warhol used them for silkscreens, not for subtle blending. If you want oil-like blending, use oils. If you want speed and permanence, use acrylics—but don't fight their nature.

One more thing: acrylics don't yellow. That's a huge advantage if you're painting something that needs to stay bright. But they also dry darker than they look when wet. So test your colors on a scrap canvas first. I keep a small 'swatch book' of dried acrylic samples next to my easel. It's saved me from more than one muddy mess.

Is watercolor really the hardest medium?

It's unforgiving, but not the hardest. Watercolor uses pigment bound with gum arabic and relies on the white of the paper for highlights. You can't paint over mistakes with opaque white—unless you add white pigment, which turns it into gouache. That transparency is the challenge. But here's the thing: you can lift color with a damp brush, and you can plan your lights. The hardest part is knowing when to stop. Egg tempera, by contrast, dries almost instantly and can't be reworked at all. So no, watercolor isn't the hardest—it's just the most public. Every mistake shows.

If you want to make watercolor easier, try this: tape your paper to a board and wet the entire sheet before you start. Then paint into the damp surface. You'll get soft edges and fewer hard lines. I do this for skies. It's almost foolproof. Almost.

What's the most overrated painting technique?

Impasto. Everyone loves thick, juicy strokes—Van Gogh's Starry Night is built from them. But impasto is not a shortcut to expression. It's a structural risk. Thick paint on a flexible canvas will crack if the underlying layers aren't dry and lean. Titian and Tintoretto used impasto sparingly; it only became extreme in the 20th century. If you slather on half an inch of titanium white, you're not making a masterpiece—you're making a future conservation problem. Use impasto deliberately, on a rigid support, and only in the final layer.

And if you must use impasto, do what I do: paint on a wooden panel, not canvas. Wood doesn't flex. Your paint won't crack. It's that simple.

What I'd actually do

If you're starting today, pick one medium and learn its drying chemistry. For oils, buy a tube of raw umber and a tube of lead white substitute (titanium white is non-toxic and lightfast). Paint a monochrome underpainting thinned with solvent. Let it dry for three days. Then paint your final layers with more oil. That's it. No glazing, no scumbling, no impasto. Just learn to control drying. For acrylics, buy a retarder and a spray bottle. Work on one small canvas—no larger than 16 by 20 inches—and finish it in one session. For watercolor, buy 140 lb cold-press paper and one round brush. Paint a single apple. Leave the white of the paper for the highlight. Do that ten times. You'll learn more than from any 'fat over lean' sermon.

And stop fetishizing paint tubes. Yes, John Goffe Rand's collapsible tin tube, patented in 1841, made plein air painting possible. Renoir said without tubes there'd be no Impressionism. But you're not Monet. You're painting in a studio with central heating. Use tubes—they're convenient—but don't confuse convenience with technique.

One last thing: your brushes are probably fine. It's your process that needs work. So stop buying new brushes and start paying attention to drying times. That's the real secret.

Sources

• EBSCO / Study Rocket (Painting) - https://www.ebsco.com/research-starters/history/painting
• Drying oil (EPFL GraphSearch) - https://graphsearch.epfl.ch/en/concept/752713
• Winsor & Newton - https://eu.winsornewton.com/en-row/blogs/guides/three-oil-painting-rules
• Impasto (Tate Art Terms) - https://www.tate.org.uk/art/art-terms/i/impasto
• Titanium white (WebExhibits) - https://www.webexhibits.org/pigments/indiv/history/tiwhite.html
• John Goffe Rand papers (Archives of American Art) - https://www.aaa.si.edu/collections/john-goffe-rand-papers-6737/biographical-note