Give it to Me in Black and White

Lead white is one of the most well known and used pigments throughout history. It is discussed at length in ancient manuscripts and its origin as a pigment derived from lead is richly documented. However, the average person is unaware of how lead white pigment is made. Unless a person participates in the sport of fishing where lead weights are normally used to make the tackle sink. most people do not come into contact with the silver-gray metal that is the starting point for making this brilliant white pigment.

Lead must be transformed into a fine, dense, opaque white pigment by a chemical process. Today the pigment is only sold to artists and for industrial purposes. The largest use of lead today is for storage batteries as commonly found in automobiles. So how does one turn grey metal into white powder?

The modern processing of lead is a highly technical and relatively speedy process that transforms lead into pigment. In earlier times, the work required to turn lead into pigment was deceptively straightforward and required only a few materials at hand to make the transformation. Despite the appearance of simplicity, a complex chemical reaction took place to change lead into pigment. 

A thin sheet of lead was wrapped into a coil and placed in a clay pot with two chambers, the lower chamber containing acetic acid and the upper one to house the lead coil.  A hole passed through the floor of the two chambers to allow the fumes from the acetic acid to infiltrate the upper chamber containing the coiled lead. A cap was placed upon the pot to seal it. The pots were placed in a wooden shed and stacked upon each other. Fermentation of manure or tan (the bark of oaks or other trees that provide leather producers with tannin) was placed around the pots. The process of fermentation releases heat as a byproduct. The manure or tan and heat aided in converting the lead into lead hydroxide. The acetic acid in the lower chamber of the pot transformed the lead hydroxide to lead acetate. The carbonic acid in the manure or tan converted the lead acetate into basic lead carbonate that was scraped and beaten off the lead coils. The flaky white material was washed and then ground into a dry pigment.  

Black colors come from a variety of sources. While it would be assumed that all black pigment comes from a substance dug from the ground or processed from an already existing black colored material, black is far more complicated with regards to its source.  The raw products that are used to make black pigment are as varied and complex as the names that are associated with the finished paint product.

Some raw materials for black pigments may be “green.” Not a play on words or a suggestion that the underlying color has a green bias, but many of the products used to make black have no other useful life since they are byproducts from other industrial processes, thus making black pigment a recyclable and environmentally "green" material.

Bones from animals used for food production can find their way to being used to make bone black pigments. The same is true for fruit pits, grape vines, and wood scraps. Bear in mind that these materials are not set on fire and allowed to burn unregulated.  

Turning these materials into black pigment requires an incomplete oxidizing process that allows the substances to carbonize but not reduce them to ash as they would become if the burning process were open to the atmosphere. Special furnaces are designed to carbonize these materials. Other black pigments are made by the combustion of petroleum products.  Still other black pigments are derived from mineral and other mined sources.  

The hidden beauty of using a variety of materials to make black is in the undertones that are produced.  Also know as color bias, the intrigue of how black pigment looks cool or warm, can have a brown, blue or red undertone makes black an exciting part of a painter’s palette. Black can serve as a substitute for blue and painters like Rembrandt employed that knowledge when making works of art.  

Blue pigment was expensive but white mixed with black that had a cool bluish bias when surrounding by warm colors could appear to look very blue to a viewer’s eye.  

The next time you venture to an art material store look at all the names of the pigments that are black. In one case you are viewing remnants of history. Ivory black retains the name related to it when real elephant ivory was used to make the pigment. Bone Black, Mars Black, Carbon Black, Lamp Black, and many more provide artists with a wide variety of choices in one of the most basic colors made for artists.