Making Lead White (Flake White) — The Dutch Stack Process for the Most Important Pigment in Oil Painting History

MANDATORY SAFETY: Lead is a cumulative neurotoxin with NO safe exposure level. Before beginning, equip yourself with a P100 or FFP3 respirator (NOT a simple dust mask — lead particles are too fine), chemical splash goggles, and chemical-resistant gloves. Prepare your work area outdoors or in a dedicated, well-ventilated space that can be cleaned with wet wiping (never sweep — sweeping raises dust). Have wet rags available for immediate cleanup. Never eat, drink, or smoke in the work area. Keep all lead-containing materials WET whenever possible to suppress dust. Children and pregnant women must be excluded from the work area at all times.

Obtain pure lead ingots and cast or beat them into thin sheets approximately 1-2 mm thick. Cut the sheets into strips roughly 5 cm wide and 30 cm long. Roll or coil each strip loosely into a spiral, leaving gaps between the layers so that air and acetic acid vapour can reach the maximum surface area. The thinner the lead and the more surface area exposed, the faster and more complete the corrosion will be. You need approximately 1-2 kg of lead to produce a useful quantity of pigment — roughly 500 g of lead white per kg of lead consumed.

Use unglazed earthenware pots or ceramic jars with a narrow ledge or internal support about one-third of the way up from the bottom. Pour wine vinegar into the bottom of each pot to a depth of 3-5 cm (the vinegar must NOT touch the lead). Place the coiled lead strips on the ledge above the vinegar level. The vinegar provides acetic acid vapour, which initiates the corrosion — without it, the lead would simply oxidise to litharge (lead monoxide, PbO), which is yellow, not white. Close each pot loosely with an earthenware lid — the lid should not be airtight, as CO₂ must be able to enter.

Build a stack outdoors: lay a thick layer of fresh horse dung (15-20 cm), place a row of the loaded pots on top, cover with another layer of dung, then another row of pots, and so on. The stack should be covered on all sides with dung and protected from rain. The composting dung serves two critical chemical functions: (1) it generates gentle, steady warmth of 35-50°C as it decomposes, which accelerates the chemical reaction, and (2) the decomposition produces carbon dioxide (CO₂), which is the essential reagent that converts lead acetate into basic lead carbonate (the white pigment). Without the CO₂, only lead acetate would form — a soluble, non-pigment compound.

Leave the stack undisturbed for 4-12 weeks, checking the dung temperature periodically by inserting a hand. It should feel distinctly warm (35-50°C). If the dung cools and stops composting before the process is complete, add a fresh outer layer of dung to restart fermentation. After 6-8 weeks, open one test pot to check progress — the lead strips should be substantially or completely coated in a thick, white, flaky crust of basic lead carbonate. If significant metallic lead remains, re-seal and wait longer. Complete corrosion can take up to 12 weeks depending on temperature and ventilation.

Wearing full protective equipment (respirator, goggles, gloves), remove the pots and scrape the white corrosion crust from the lead strips. Any remaining metallic lead can be re-used in future batches. Wash the white flakes several times with clean water to remove residual vinegar and impurities. Keep the pigment WET at all times during handling to prevent dust. Grind the wet flakes on a glass muller with a small amount of water until smooth, then spread the paste to dry in a well-ventilated area away from foot traffic. Once dry, store in sealed glass jars, clearly labelled as toxic. Lead white is supremely opaque, warm-toned, and produces the most beautiful, buttery oil paint of any white pigment — but it must always be handled with extreme caution.