What was on the bronze?

Tests indicate that what was on the surfaces of the Tyler Davidson bronzes was some mixture of pigments and wax(es) applied by the Karkadoulias firm. The contents of the coating have not been revealed by the firm and some conservators attempting to remove their coatings from other sculptures were told that the formulas are secrets. Pigments in waxes are used by professional bronze conservators also but only as a last resort for the coloration of very badly deteriorated bronze, to obtain unusual colors, or rarely, as an inexpensive coloration method. When pigmented coatings are necessary, their use is made known to the owners for their approval beforehand, and the composition and application processes of the coatings are well documented.

What was wrong with the green coating on the bronzes?

For one, the coating on the bronzes had deteriorated. It had become stained with calcium and magnesium, some areas had darkened. Other areas no longer provided protection to the metal. But just as important, the thick, opaque, and dark green coating was not a patina which would have been considered historically correct for this sculpture. Such opaque, dark green surfaces were popular for a time beginning in the early part of the twentieth century after an acceptance of the formation of thick, dark green copper corrosion on outdoor bronze as "natural" and "beautiful.' But it was our modern, industrial atmosphere laden with sulfur dioxide which was responsible for aggressively turning bronze to greens and blacks. Before this time, such as in the mid-nineteenth century, artists and the public, in general, appreciated clean bronze perhaps with thin transparent oxides of brown and sometimes even a little green as desirable patinas. As our atmospheres increased in pollution, people were surprised to see the rapid formation of these green corrosion products on copper roofs and on sculpture and made efforts to study and eradicate their formation. The dark and opaque green on the Tyler Davidson bronzes then, represented a mistaken acceptance of what was actually active and damaging corrosion on bronze as a desirable patina.

What is a Patina?

Defining the meaning of "patina" is fraught with the complication of variations in historical usage. Simplistically, what is on the Tyler Davidson bronzes now is not a patina in the modern sense nor in the sensibility of much of the nineteenth century. A bronze patina is thought of nowadays and then as an attractive, desirable, formation of copper compounds (bronze is an alloy of copper with tin, zinc and lead) having various colors, most commonly translucent greens and browns. These will form over time on a bronze surface or can be artificially induced with chemicals. It is bronze metal where the bright new surface has mellowed with the formation of thin films from age. Heavy, opaque encrustations of various green and black copper compounds which develop in reaction to modern atmospheres' especially those laden with sulfur, are today, as in 1867, recognized to be corrosion rather than patina. This has not always been the definition of patina. It is thought that the ancient Greeks took efforts to maintain their bronzes as a bright metal. Later, the mellow brown oxide film which forms on bronze became a desired patina. The word "patina" as a weathered surface on bronze eventually became associated with the heavy, opaque greens of copper compounds in the late nineteenth and early twentieth centuries. At the turn of the century, an opaque black, which also forms naturally on bronze in sulfur polluted air, was desired. Currently, we accept both a variety of browns and greens, and even other unnatural colors, but prefer, as did those in the mid-nineteenth century, within the definition of "patina," a translucent effect which does not disguise the metal. Bronze will naturally and gradually attain these colors from reaction with the environment or similar colors can be quickly formed through chemical applications and reactions. We desire such naturally formed colors but not to the extent of thick encrustations. When these patina colors are desired as part of the aesthetics of a sculpture, they can be preserved through application of clear waxes and sometimes a synthetic resin. The result is both color and a rich translucency which gives the viewer a sense that there is bronze metal there; that is, that they are looking at the surface of a well cared-for but moderately weathered bronze. An 1892 manual Metal Colouring and Bronzing by Hiorns of London offers: "It should also be borne in mind that a metallic article is not like canvas or paper which has to be completely covered with paint of all colours ... but a material which must always assert its peculiar metallic character, so that there is never any doubt as to its real nature." The effect of imitating the natural formation of colored copper compounds through reaction of the bronze with chemicals is preferred over the effect of pigments applied to the surface of bronze. Heavy applications of pigments in wax as evident on the Tyler Davidson bronzes, can not achieve this look. Essentially, the "patina" on the Tyler Davidson bronzes is paint in imitation of severe corrosion and one is looking at paint in this case, not bronze. This is undesirable.

What will be the new finish on the restored bronze?

Testing repatination methods

How is the work done?

repatination

Other responsibilities of the Conservator

The conservator oversees and is integrally involved with all work impinging on the bronze such as any drilling, attachments, and the design and installation of a new stainless internal supporting structure. The conservator advises on water chemistry and aesthetic effects affecting historical preservation. The conservator, in collaboration with the general contractor, oversees electrical installation, plumbing installation, concrete and masonry work, and all rigging and movement of the bronze.