Blue Verditer

PB28—Synthetic mineral - discovered by Thénard in 1802. A favourite of the Impressionists and Post-Impressionists - Monet and Renoir used it for skies and shadows where ultramarine read too warm. A clean, reliable, mid blue - stable in all conditions, though it requires care because of its cobalt content.

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.

PB36—Synthetic mineral - a cobalt-chromium variant. A 20th-century addition with no Old Master pedigree, cobalt turquoise gives contemporary painters a cool, mineral sky-and-water blue. A permanent, granular turquoise for seas, skies and cool greens - the cool end of the cobalt family.