Flake White (Lead Carbonate)by George O'Hanlon
Posted by Philip:
Flake white is most easily identified as genuine by the pigment number and the posionous labeling on the package. There are certain pigments such as arsenic based ones which are no longer commerically available because it is a controlled substance. Most of the posionous pigments can still be obtained through specialty pigment and paint manufacturers. I am not sure which pigment manufacturer it was that still supplies flake white, I will have to check next time.
Philip, I think we are miscommunicating on the subject of lead white. My point is that “Flake white” is a name that originally designated a basic lead carbonate pigment produced by the “Stack process” or “Dutch method.” There are no manufacturers today producing basic lead carbonate pigment using the “Stack process” on a commercial scale. I know of several individuals who are making lead white in this manner for their own use. Today, the number of manufacturers producing basic lead carbonate in the entire world could probably be counted on one hand. In the U.S., Halstab still produces basic lead carbonate but with another process that produces particles of a different shape and size distribution than obtain with the “Stack process.”
A few weeks ago, I was visited the conservation department at the Tate Britain, and Leslie Carlyle, head of conservation, showed me numerous ESM images of basic lead carbonate produced by different methods, all of which were significantly different from each other. What was most interesting was a scan of a slice of a lead white paint layer from a Rembrandt painting and slices of lead white paint layers made using different processes. Only the “stack process” lead white makes a layer that appears identical to Rembrandt’s lead white.
Natural Pigments has a lead corroding stack in process that should yield nearly half a ton of basic lead carbonate pigment. This pigment will be ready before the end of the year and also available as ready-made oil paint.