I was recently contacted by Camille Polkownik from the Hamilton Kerr Institute, University of Cambridge, asking if they could obtain a small amount of my Stack Lead White powder, to be analysed for research purposes (You can find their analysis results at the bottom of this page). Of course I obliged and in return I received a very favourable outcome on my handmade Stack Lead White.
There is something in the nature of the Old Masters oil paints–particularly in whites–which cannot be replicated with today’s paints because the modern method for making lead whites is not the way they were made during the time of the Old Masters. To recreate the actual white pigment that would have been familiar to artists such as Rembrandt, Titian and Vermeer, I researched lead white recipes and the old Dutch stack process.
The result is, today I make my lead pigment in small hand-made batches following the time-honoured Dutch stack lead procedure. The process starts with creating and collecting the raw materials known to the Old Masters.
Many scholars have noticed there is something different in the nature of Rembrandt’s oil paints, particularly his whites that cannot be simulated with modern made whites today. Prior to the industrial revolution lead whites were made roughly in the same way, by suspending lead over vinegar in a container and then burying under horse dung for the appropriate amount of time. Yes, that’s right its not a typo – horse dung is a key raw materials in making Stack Lead White! The chemistry that takes place is well understood and quite simple in broad terms. For more click here
From The Hamilton Kerr Investigation:
Using the Dutch stack historic technique, every pigment particle of Stack Lead White is unidentical. Therefore, every conglomeration of pigment particles on a nano-scale behaves differently. This is precisely the beauty of Stack Lead White. With industrially-made pigments, every particle is identical!
Using tests such as Polarised Light Microscope and X-ray Diffraction, the analysis Hamilton Kerr Institute, of University of Cambridge discovered;
“The product is pure and unadulterated, which indicates there are no extenders such as calcium carbonate (chalk), titanium white (titanium dioxide) or calcium sulfate (plaster). Extenders would make the product cheaper, but also weaken the qualities brought by the lead white, ie. opacity, particular handling properties (impasto, thixotropy), accelerated drying.”
“Consistent with other traditionally made lead white, and most importantly, that the pigment was pure and had not been cut with extenders to reduce cost, which would have had an impact on the handling and optical properties of the pigment.”
The paper is to be published in the 2018 Hamilton Kerr Bulletin under the title: “Lead White, How Variations in the Crystalline Phases Influence Handling and Optical Properties”.
You are welcome to view the results and article by clicking the link below;