BLOCKX watercolours are made from rare, light-resistant pigments that are very finely ground and coated in gum arabic and honey. On a quest for excellence, Jacques Blockx IV developed 72 shades of watercolour with the addition of honey to increase the resistance of the colours over time and lend them greater brilliance and luminosity. BLOCKX Watercolours are made using only lightfast pigments to ensure stability because watercolour is a naturally fragile medium. The most intense and brilliant pigments, which always can be diluted but never improved. Made by hand in Belgium. 15ml tube. 452 Cobalt Blue. Series 4. Pigment code PB28. Transparent pigment opacity.