Oil paint offered Renaissance artists something tempera couldn’t: slow drying times, rich color depth, and the ability to blend colors directly on the surface. These advantages were so significant that by the sixteenth century, oil had largely replaced egg tempera as the dominant painting medium across Europe. The shift wasn’t instantaneous, though. It unfolded over roughly a hundred years as painters discovered what the new medium could do.
Why Oil Paint Replaced Tempera
Until the fifteenth century, egg yolk was the most widely used binder for pigments. Tempera worked well for the flat, luminous panels of medieval and early Renaissance painting, but it came with real limitations. The water in the egg yolk (which makes up about 51% of yolk by weight) evaporated quickly, meaning the paint dried fast. That speed forced artists to work in small, careful strokes rather than broad, blended passages. You couldn’t easily go back and rework an area once it set.
Oil paint changed the pace entirely. Linseed oil doesn’t dry through evaporation at all. Instead, it undergoes a chemical reaction with oxygen, sometimes described as a form of “flameless combustion.” The unsaturated fatty acids in the oil slowly crosslink into a dense, tangled polymer network. This process takes four to six days just to become touch-dry, and the oil gains 15 to 20 percent in mass as it absorbs oxygen during that period. That extended working window let painters blend colors smoothly on the panel or canvas, make corrections, and build up layers over days or weeks.
Richer Color and Transparency
The optical difference between oil and tempera is striking. Linseed oil has a refractive index of about 1.48, which is close enough to many pigments that light passes through the paint film rather than scattering off the surface. This creates depth. Colors appear more saturated, shadows look deeper, and transparent glazes become possible. A painter could layer thin, translucent coats of oil paint over opaque ones, building up a glow that seemed to come from within the painting itself.
Tempera, by contrast, dries to a more opaque, matte finish. The egg proteins and water create a film that scatters light differently, producing bright but comparatively flat color. Tempera paintings have a chalky luminosity that’s beautiful in its own right, but the medium can’t achieve the same illusion of three-dimensional space that oil glazes produce. This is why early Netherlandish painters like Jan van Eyck were able to render textures so convincingly in oil: the sheen of armor, the transparency of water, the softness of fabric. Van Eyck’s work captured rippling water, moving clouds, and fine textural differences between materials in ways that tempera simply couldn’t replicate.
Blending and Corrections
The slow drying time of oil wasn’t just convenient. It fundamentally changed how painters could compose an image. With tempera, you had to plan every stroke in advance because the paint set within minutes. Colors were layered through hatching (fine parallel lines placed side by side) rather than blended smoothly into one another. Soft gradations from light to shadow required painstaking, methodical buildup.
Oil paint could be pushed around on the surface while still wet, creating seamless transitions between tones. An artist could model a face, soften the edge of a shadow, or adjust the curve of a hand hours after first applying the paint. This ability to work “wet-in-wet” made oil painting more forgiving and more responsive to an artist’s creative decisions in the moment. The longer drying time also allowed corrections. If something wasn’t right, you could scrape it off or paint over it before the layer cured.
The Transition Wasn’t Sudden
Oil as a paint binder existed before the fifteenth century, but it was the virtuoso handling of the medium by early Netherlandish painters like Jan van Eyck and Rogier van der Weyden that represented a turning point. Van Eyck was long (and incorrectly) credited with inventing oil painting, but what he actually did was demonstrate its full potential. His work was so impressive that when the Spanish artist Joan Reixach mentioned owning a painting by Van Eyck in his 1448 will, he specifically noted it was painted in oil, still a novelty in that part of Spain.
Many painters during this transitional period didn’t choose one medium exclusively. Research published in Nature Communications has shown that Old Masters frequently added egg yolk to their oil paints, creating a hybrid called “tempera grassa.” The egg yolk acted as an emulsifier, helping to stabilize the mixture of oil and water-based components. This combination could actually reduce some of oil paint’s drawbacks, including wrinkling, cracking, yellowing, and darkening. From a physical chemistry standpoint, the yolk’s lipoproteins spread across the surface of oil droplets, stabilizing the emulsion. These hybrid systems dried through a combination of water evaporation and the same oxidative crosslinking that pure oil paint undergoes.
Durability and Aging Tradeoffs
Oil paint forms an extremely durable film, but it isn’t without aging problems. Over centuries, the linseed oil binder yellows noticeably, especially in areas with heavy medium and less pigment. Fatty acids released from aging oil can react with certain white pigments to form metal soaps, which make the paint layers more transparent over time. This is why dark underlayers sometimes become visible in old oil paintings, altering the artist’s intended composition. Too much oil in the paint mixture also increases the risk of cracking and wrinkling, a problem Leonardo da Vinci himself encountered.
Tempera, on the other hand, ages differently. The egg protein film is relatively stable and doesn’t yellow the way oil does. Tempera paintings from the thirteenth and fourteenth centuries often retain remarkably bright, clear color. But the film is more brittle, and tempera panels are vulnerable to flaking if the underlying wood expands or contracts with humidity changes. Neither medium is perfectly permanent, but they fail in different ways over the centuries.
What Oil Made Possible
The practical advantages of oil paint map directly onto the artistic revolutions of the Renaissance and beyond. The ability to blend soft transitions enabled realistic modeling of the human form. Transparent glazes allowed painters to simulate the way light actually behaves, passing through skin or bouncing off polished metal. The slow working time encouraged a more spontaneous, exploratory approach to composition. And the rich, saturated color gave painters a wider effective range from their pigments, even when using the same mineral and earth colors available to tempera painters.
Tempera remained in use for specific purposes, particularly for underpaintings and for artists who preferred its crisp, precise line quality. But for the broad ambitions of European painting from the sixteenth century onward, oil became the standard because it removed constraints. It let painters work at the speed of thought rather than the speed of evaporation, and it produced results that looked, to contemporary eyes, closer to the visible world than anything that had come before.