What Is Oil Painting?
Oil painting is paint made by grinding pigment into a drying oil, usually linseed. Because the oil dries slowly, the artist can blend colors on the surface for hours, build up transparent layers, and create soft, deep, glowing effects that faster mediums cannot. It became the dominant way to paint in the West for over five hundred years.
It was not the first way to paint.
But it was the one that changed what painting could do.
Oil painting, the basics
What it is: pigment ground into a slow drying oil like linseed.
The gift: it stays wet, so you can blend and rework for hours.
The look: deep color, soft transitions, glowing layered light.
The shift: it replaced egg tempera as the main medium.
The pioneers: the early Netherlandish painters, above all van Eyck.
Why slow drying changed everything
The magic of oil is time.
Egg tempera, the medium oil replaced, dries almost instantly, so colors must be built in tiny separate strokes and cannot be blended on the panel. Oil stays wet for hours or days. Suddenly a painter could soften one tone into another, melt a shadow into a cheek, and wipe back and rework at will. The smoky, seamless transitions of later painting only became possible because the paint refused to dry in a hurry.
Slow paint gave artists time to think with the brush.
Layers and glazes
Oil also lets light travel through the paint.
Painters built pictures in layers: a monochrome underpainting to map the light, then thin transparent films of color called glazes laid over it. Light passes down through the glazes, bounces off the bright layers beneath, and comes back to your eye colored and deepened, the way light glows through stained glass. It is how old masters got reds and shadows that seem lit from within.
Oil does not just sit on the surface. It catches light inside itself.
From smooth to thick
Oil is also wonderfully physical.
Because it holds its shape, oil can be piled on thick, the raised, sculptural paint called impasto, or smoothed until no brushstroke shows at all. The same medium gives you the glassy polish of an Ingres and the loaded ridges of a Van Gogh. Few materials stretch so far between control and freedom.
One paint, two opposite kinds of beauty.
The invention that gets misremembered
There is a myth worth correcting.
Van Eyck is often called the inventor of oil painting. He was not. Oils had been used before him. What van Eyck and his fellow early Netherlandish painters did, in the 1400s, was perfect it: refining the recipes and layering until oil could render fur, jewels, skin and light with a realism the world had never seen. The Arnolfini Portrait is not the first oil painting, but it is the moment oil announced what it could do.
He did not invent the medium. He revealed it.
Two landmarks of oil hang in Europe. Van Eyck’s Arnolfini Portrait is in the National Gallery, and Leonardo’s Virgin of the Rocks in the Louvre.
The recipe that took centuries to crack
Oil paint sounds simple, pigment plus oil, but making it behave took generations of trial and error. The early Netherlandish painters around van Eyck worked out which oils dried well, how to layer thin glazes, and how to stop colors yellowing, and they guarded these recipes closely.
Later painters were not always so careful. Some of Joshua Reynolds’ pictures began cracking and fading within his own lifetime because of unstable mixtures, and certain bituminous browns never fully dried at all. The freedom of oil came with a chemistry that could betray you.
Out of the studio in a tube
For most of its history oil painting was chained to the studio, where colors were ground fresh and used fast. That changed in 1841, when the American painter John Goffe Rand patented the collapsible metal paint tube.
Suddenly ready oil color was portable and sealed, and painters could carry it into the fields. Without that small invention there would have been no Impressionism painted outdoors in front of the subject. A medium five centuries old was handed a second life by a piece of squeezable tin.
Oil let painters model skin and fur with a softness tempera never could, as you can see up close in Leonardo’s Lady with an Ermine.
Common questions about oil painting
What is oil painting? Paint made of pigment ground into a slow drying oil, usually linseed.
Why did it replace tempera? Because it dries slowly, oil can be blended and reworked, which tempera cannot.
What is a glaze? A thin transparent layer of oil color laid over another to deepen and enrich it.
Did van Eyck invent oil painting? No. He and other early Netherlandish painters perfected it, rather than inventing it.
Why is oil so versatile? It can be smoothed invisibly or piled on thick, giving everything from glassy polish to heavy texture.
The paint that let painting grow up
Almost everything we picture when we think great painting, the deep shadows, the glowing skin, the seamless light, came from one practical fact: oil dries slowly.
That single property handed artists time, and with time came blending, glazing, reworking and risk. For five centuries oil was not just a material. It was the freedom that let painters chase the look of real light and real flesh. The medium did not just record the masterpieces. It made most of them possible.