Every morning for 42 years, Piet Kempenaar has been scanning the Dutch sky, adjusting the sails to the force of the wind before releasing the brake and maneuvering the giant blades of his centuries-old mill. De Kat is the last windmill in the world to use wind power to turn rocks into paint pigments, as was done nearly 400 years ago. Driven by a system of wooden gears, ropes and pulleys, two huge millstones weighing ten tons in total grind a variety of hard rocks for hours, turning them into colorful dust.
Although he left most of the milling duties to his son Robert, the 73-year-old still has the gnarled figure and allure of a Dutch miller, with his blue worker’s jacket streaked with pigment dust, a fisherman’s cap and a pipe in his mouth. “I’m not interested in painting, but I’m obsessed with pigments,” he points out.
De Kat (the cat, in French), located on the picturesque but very touristy village of Zaanse Schans north of Amsterdam, began to transform rocks into pigments in 1646, he explains. The original mill burned down in 1782, and over the centuries has been rebuilt and refitted several times for different uses, before resuming its rock crushing duties in 1960.
Since 1981, Piet Kempenaar has praised De Kat to the local mills association for his pigment manufacturing business, which attracts thousands of buyers each year. The mill is now the last link to the original method of making paint, before the process was industrialized around 1850, experts say.
“Here we have the king of blue. It’s a half-diamond from Chile or Afghanistan,” explains Piet Kempenaar, pointing to a block of striking blue. “This is lapis lazuli, used by Johannes Vermeer,” he adds. Dozens of other types of pigments ground by De Kat are neatly stacked on shelves: Verona green earth, dark Cyprus umber or carmine red, a dye that comes from the grinding of female cochineals from the Canary Islands, between others.
“We grind pigments the old-fashioned way here. That’s why people from all over the world buy from us. It’s unique,” rejoices Piet Kempenaar. Many Dutch masters produced their most famous works during the Dutch Golden Age, in the 17th century. Many of the pigments they used almost certainly came from “paint mills”, scattered across the Dutch landscape at the time. Among them is the precious lapis lazuli, which was used to produce the ultramarine paint with which Vermeer colored The Milkmaid’s apron.
At the Rijksmuseum, art teacher Peter Pelkmans meticulously prepared a paste from lapis lazuli pigments mixed with linseed oil to make ultramarine blue paint. At the Tekenschool (drawing school) of the Amsterdam museum, thanks to De Kat pigments, amateurs and artists still have the chance to learn how to paint like in the time of the great Dutch masters.
“We give people the chance to go back in time,” says Peter Pelkmans, before mixing a burnt sienna, very dear to Rembrandt in particular. The Dutchman was, however, known to grind his own pigment in a giant iron mortar in his workshop, and used a cheaper pigment called ‘smalt’ as a substitute for the precious and expensive lapis lazuli pigments.
But this pigment used by Vermeer was almost certainly ground in a windmill, the expert believes. And “often the blue was the last part of a commissioned painting. The artist only added it once he had been fully paid,” he notes.