Recently we have become aware of a trend to incorrectly label electroformed bronze bookends as copper. One antiques and collectibles site, Eureka, I Found It, states unequivocally that “Armor Bronze, Pompeian Bronze, and Marion Bronze” are zinc with a copper coating, produced by the “Electroformed” or “Galvano” method.
The Bookend Collector is always Interested in obtaining more information, and recognizing that actual analysis of metal on electroformed or plated bookends is often missing, we contacted the site and asked for supporting documentation for their statement. Their response was, “……bronze could not be electroplated so it must be copper.”
They are wrong. Bronze can be electroplated. Bronze, according to the Encyclopedia Brittanica, is traditionally an alloy composed of copper and tin, in varying proportions. In modern times bronze alloys have varied in composition and while bronze is primarily copper the alloy may include zinc, lead, manganese, aluminum. It’s hardness and strength is improved by the addition of a small amount of phosphorous. In the excellent treatment of Electroformed / Galvano Castings in Gerald P. McBride’s “A COLLECTOR’S GUIDE TO CAST METAL BOOKENDS,” after speaking to the owner of Marion Bronze, he writes ….“The process of electroforming was actually more detailed than it would first appear and required special attention to the amounts of electrical current used and the CHEMICAL COMPOSITION OF THE PLATING SOLUTIONS (my caps).”
So far as we know, the metal in electroformed bookends has never been analyzed, and, as yet, we’ve not found the formulas used by the various bookend foundries, so the identity of the metal is not certain. We do know that electroformed bookends are not plated on zinc, but are plated or electroformed on a composition material or on chalk, this is one difference between electroformed bookends and plated metal bookends. Additionally, in the electroformed bookends the plating or coating is thick enough to stand on it’s own if the matrix were removed. In plated metal bookends the plating is usually very thin and is often reduced or removed by dusting or heavy cleaning. Click here to read our earlier post on electroformed bookends. Also, there is a discussion of electroforming in BOOKENDS: Objects of Art and Fashion on page 159.
Companies that made electroformed bookends include Paul Mori, Armor Bronze, Marion Bronze, Kathodian Bronze Works (KBW). These foundries claim bronze and there is no reason to doubt them, so we will continue to regard the metal as bronze until proven otherwise.
Some companies that made 3-dimensional, plated metal bookends are Jennings Brothers, Weidman Brothers, …….. The plating may be copper or bronze or other metal on zinc or other gray metal.
A further observation regarding electroformed bookends versus 3-dimensional plated bookends: in electroformed bookends there are no seams as the plating is done over a matrix, in plated 3-dimensional metal bookends there are seams, usually polished off, where electrotyped pieces of the sculpture are joined. Click here to view an excellent video from the Metropolitan Museum of Art that shows the process employed in electrotyping – a process that mirrors how bookends from foundries such as Jennings Bros. would have been made.