Oil Paint and the Northern Renaissance Surface

Egg tempera, the dominant medium before the 1400s, is egg yolk mixed with pigment. It dries almost instantly, so painters work in small, quick, opaque strokes and build form with hatching, not blending. Oil paint, pigment suspended in linseed or walnut oil, dries over days or weeks. That slowness is the whole advantage. A painter can blend wet paint smoothly, soften edges, and apply glazes: thin, transparent layers of oil and pigment laid over a dried underlayer. Light passes through each glaze, bounces off the layer below, and comes back through again, like looking through colored glass stacked on glass. Colors mixed this way have a depth and glow no single mixed-on-the-palette color can match, and the slow working time lets an artist pick out individual hairs in a fur collar or the exact glint on a pearl.

This technical shift happened in Flanders in the 1400s, with Jan van Eyck as its most celebrated practitioner. Oil-based paint already existed in Europe before him; what van Eyck and his contemporaries did was refine layered glazing into a controlled, repeatable method and show the world what it could do. His Arnolfini Portrait (1434) and the Merode Altarpiece use this technique to build interiors so convincing you can read fabric, metal, and reflected light as if looking through a window.

This sits beside Italian Renaissance developments like one point perspective: both are tools for constructing convincing illusionistic space, one through optics and geometry, the other through surface and light.