Litharge (Massicot) Pigment

WARNING! Contains Lead. Read the SDS for cautionary statements.

Rublev Litharge is made by a modern process of direct oxidation of lead, wielding a finely divided yellow-orange powder of high purity. Litharge is monoxide of lead and usually contains about 93 percent of lead and 7 percent of oxygen. It is not used as a pigment in oil painting but in manuscript illumination (egg tempera and watercolor) and infrequently in fresco painting.

Origin and History

Both massicot and litharge are often terms used for the same pigment, but more correctly, each is a lead monoxide derived from different sources. Massicot is the unfused monoxide of lead made by gently roasting white lead at 300° C. The heat causes the white lead to give off carbon monoxide and water, leaving a soft, sulfurous yellow powder that is massicot. Litharge is the fused and crystalline oxide formed from the direct oxidation of molten metallic lead. Litharge is more orange compared to massicot due to the content of some red lead (lead tetraoxide). Litharge is rarely used as a pigment compared to massicot but was more commonly employed in varnishes and glazes. The manufacture of yellow lead monoxide has been known since Ancient times and is found in Egypt, Europe, and North and South America.

The name massicot is derived from early Arabic, through the Spanish mazacote and the French name for oxide of lead.

Source

Lead monoxide exists in two modifications: litharge and massicot. Litharge, or alpha lead monoxide, is a red or reddish-yellow solid, has a tetragonal crystal structure, and is stable at temperatures below 488° C (910° F). Massicot, or beta lead monoxide, is a yellow solid with an orthorhombic crystal structure; it is stable above 488° C. Massicot is the orthorhombic variety of PbO. The tetragonal variety is the mineral litharge. Both minerals have the same chemistry, PbO, but different structures. Because of this, they are called dimorphs (“di” means “two,” and “morph” means “shape”). Two other much more famous dimorphs are diamond and graphite, which are composed of carbon. Litharge is similar to the more common massicot, but the tetragonal structure is lighter than massicot’s structure. Litharge is also more orange in color. The two minerals are easily distinguished in petrographic microscopes due to optical differences. It has been found that many crystals of massicot have a fringe of litharge.

Litharge, produced by the oxidation of lead, is the most important commercial compound of lead; it is used in large amounts directly and as the starting material for preparing other lead compounds. Containing roughly 93 percent lead and seven percent oxygen by weight, it is manufactured by oxidizing metallic lead in various processes, each resulting in a distinctive variation in physical properties. Hence, it is available in many particle sizes and two crystal forms.

Permanence and Compatibility

The color appears permanent in all mediums, but due to its siccative effect on oil, it cannot be used as a pigment in this vehicle. Litharge is an effective drier in linseed, poppy seed, walnut, and safflower oil.

Uses in Oil Painting Mediums and Varnishes

The following are directions from Mackenzie’s Five Thousand Receipts in All the Useful and Domestic Arts by Colin MacKenzie:

“When painters wish to obtain a common colour of the ochrey kind, and have no boiled oil with them, they may paint with linseed oil, not freed from its greasy particles, by mixing with the colour about two or three parts of litharge, ground on piece of porphyry with water, dried, and reduced to fine powder, for 16 parts of oil. The colour has a great deal of body, and dries as speedily as if mixed with drying oil.”

How to Make Drying Oil

The following are directions from Mackenzie’s Five Thousand Receipts in All the Useful and Domestic Arts by Colin MacKenzie:

“Boil together for two hours on a slow and equal fire, half an ounce of litharge, as much calcined ceruse [Note: Substitute calcined ceruse with litharge], and the same of terre d’ombre [Nd’ombreber] and talc [Note: hydrated magnesium silicate], with one pound of linseed oil, carefully stirring the whole time. It must be carefully skimmed and clarified. The older it grows, the better it is. A quarter of a pint of this dryer is required to every pound of colour.”

Italian Medium

Another source describes the following recipe as a method of preparing a drying oil painting medium with litharge and wax, essentially making a “black oil.“ Jacques Maroger first described this medium on page 164 of his book Secret Formulas and Techniques of the Masters. It is made in the following way (all measurements are given by weight):

Raw linseed oil ...........................10 parts
Litharge ........................................ 1 part
Beeswax ....................................... 1 part

“It is advisable to grind the litharge with a little of the oil before mixing it with the rest of the oil. The mixture is then heated to 250° C., and when it turns black, the product is finished. Upon cooling, it thickens into a paste.“

“In actual usage, the results are very close to the true Italian medium. This paste has the advantage that anybody can make it without difficulty. It is mixed (by means of the palette knife) into each color on the palette, including the white. There can be no definite prescription for its use, as it is a matter of individual taste; the use may vary with different subjects. It can be thinned with raw oil or, preferably, with gum turpentine. This can be worked into it with the palette knife for use on the palette or kept in the oil cup for further dilution of the colors.“

Oil Absorption and Grinding

Litharge is not used as a pigment in oil painting because of its siccative effect on oil. It can be used with aqueous media such as egg tempera, gum Arabic (watercolor), and animal glue. It can also be used in the encaustic (wax) technique and in the true fresco technique.

Toxicity

Litharge is toxic if inhaled as dust or if ingested. Using pigment to make paint or dry oil can be hazardous, so protective clothing and work hygiene must be used to ensure safe use. The sale of lead compounds in some countries has been prohibited. Painters may suffer from “painters’ plumism“  if they are careless using it. Care should be used when handling the dry powder pigment so as not to inhale the dust. Do not smoke, eat, or drink while using the pigment in any form, including in a paint binder.

Rublev Colours Pigment: Litharge (Massicot)