Conservators who are involved in the restoration and preservation of Works Progress Administration (WPA) murals and those of close era may find the following recommendations and formula regarding lead white in varnish, of interest. A photostatic copy of the undated pamphlet described below is in our library.
A serious hazard and difficulty of mural conservators’ work when mural removal is necessary is dealing with the toxic and tough so-called “lead white adhesive.” This is usually a paste made of white lead carbonate and linseed oil. Lead carbonate accelerates the oxidation of linseed oil, hastening the hardening of the paste and producing a exceptionally hard and insoluble film. The following excerpt from a government WPA publication recommends, instead, the use of lead carbonate in resin for increased adhesion contributed by the tackiness of the resin but does not mention the role or benefit of the lead carbonate in this formula.
One of the divisions of the WPA Federal Art Project at 235 East 42nd St. in New York City was the Restoration, Installation and Technical Service Division headed by Raphael Doktor. The Mural Division at this time was headed by well-known artist Burgoyne Diller. Doktor wrote a technical pamphlet called “Canvas Adhesives” which was distributed by the Department of Information as the second title among the series “Technical problems of the Artist.”
Excerpts from pamphlet called “Canvas Adhesives”:
“It must be mentioned here that the WPA has investigated all proposed (adhesive) mediums and will continue to do so, but thus far nothing more satisfactory than the white lead-resin mixture has been evolved.
“In the Federal bulletin mentioned before, it is stated that ‘an oil adhesive, such as lead white with linseed oil, has a tendency in time to darken the painting.’ This is probably true, but such a mixture is not used in professional practice as the linseed oil does not have sufficient adhesion.
“We here recommend a white-lead-resin varnish mixture which is quite a different substance from the lead-oil mixture, both in physical and chemical properties.
“Commercial white lead – heavy paste—is basic lead carbonate containing 9% linseed oil, the medium for grinding into paste. This may be further reduced by drainage cuts after having set in the can. To this is added dammar varnish or venice turpentine, both resins.
“This mixture forms a strong adhesive which remains tacky for long working periods”.