Lake
A dye that has been turned into a pigment: precipitated onto a transparent inert powder so it can be suspended in oil instead of dissolved in water. Lakes gave European painting its most beautiful reds, and then took a good number of them back.
Where the word comes from
Nothing to do with a body of water. The word travels from Persian and Sanskrit lakh, the lac insect whose resinous secretion produced a red dye, through Italian lacca. The technique is chemical: dissolve the dye, add alum and an alkali, and the dye locks onto the particles of aluminium hydroxide that form. What settles out is a coloured powder that behaves like a pigment while keeping the transparency of a dye.
In the studio
That transparency is the point. A lake laid as a glaze over an opaque underlayer produces a red that no single opaque pigment can equal — the light goes through the glaze, hits the layer beneath, and comes back coloured twice. The standard trick was madder or cochineal glazed over vermilion: vermilion supplies the body and brightness, the lake supplies the depth. Painters bought lakes at several qualities, from the best cochineal down to scrapings recovered from the dyers' vats — literally the waste of the textile trade, sold on to the colour trade.
Why it matters
Most lakes are fugitive, and they are fugitive in a way that changes the meaning of a picture rather than just its surface. When the red glaze goes, a purple robe reads as blue, a pink sky reads as pale grey, flesh loses its warmth and turns waxy. Van Gogh is the best documented casualty: his roses and peonies were painted with a red lake that has faded almost completely, so canvases he composed as pink-and-green now hang as white-and-green, and the colour relationship he was actually working on no longer exists.
Today
The chemistry survives in the aluminium lakes used to colour sweets, tablets and printing inks, where the same precipitation trick makes a water-soluble dye behave as an insoluble particle. In artists' materials the fugitive lakes have mostly been replaced by quinacridones and other synthetics that offer the same transparency with lightfastness the nineteenth century could not buy at any price.
Pigments used: Madder and the red lakes · Alizarin crimson · Vermilion
Essays: Why old paintings look brown
See also: Vincent van Gogh · Titian · Johannes Vermeer