Kings Blue Deep

PW6—Synthetic mineral - titanium dioxide, first produced as a pigment in the early 20th century. Titanium white arrived too late for the Old Masters, who worked in lead. It became the dominant white from the mid-20th century - think of the crisp, opaque highlights in Lucian Freud’s flesh, or the brilliant whites of modern abstraction. The modern painter’s workhorse - the brightest, most opaque white available, and non-toxic. It overtook lead white through the 20th century and now anchors nearly every palette, prized for covering power and clean tints.

PW4—Synthetic mineral - zinc oxide, introduced as a painter’s white c.1780. A late arrival, zinc white was taken up by the Impressionists for clean, non-toxic tints and by 19th-century watercolourists; Turner was among the early adopters. Valued for transparency, slow drying and a lack of yellowing - the white of choice for pale tints and delicate glazes.

PB29—Synthetic - a replica of the lapis lazuli mineral, first made commercially by Guimet in 1828. Natural ultramarine, ground from Afghan lapis, was the most prized pigment of the Renaissance - reserved for the Virgin’s robes in Giotto, Titian and Vermeer. After 1828 the synthetic version democratised that blue; the Impressionists built their skies and shadows on it. From the most expensive pigment in the medieval palette to a staple of every painter’s box - ultramarine remains the definitive warm, stable blue.