In our last Gazette we supplied the labels provided at the University of Southern Indiana for its summer Carder Steuben glass exhibit. The piece described and pictured was a Blue Aurene cut to Yellow Jade vase in the Azalea pattern. The labels referred to the piece have both Blue and Gold Aurene appearances. The piece looks like it has Gold Aurene features even though it may be Blue because of the strong coloring of the underlying strong yellow jade color. At the same time the picture shows a Blue Aurene color as well. Keith Trippi of Grand Island, New York clarifies the fact that it either is Gold or Blue, but not a combination of the two.

Dear Alan,

The written material you identified this morning as “exhibit piece label notes from Susan Colaricci Sauls” appear to contain an error and an omission.

The error is that the vase identified does not have both a gold and blue Aurene casing. The body of the vase was rendered in yellow jade and has a homogeneous blue Aurene over-casing in which both the rim decoration and the bird/azalea pattern were etched.

The omission lies in the description of the manufacturing technique for Aurene. The process described is that for manufacturing a simple iridescent glass such as Verre de Soie, where the glass is sprayed with a solution of tin chloride as part of the finishing process prior to annealing. The manufacture of Aurene was far more involved. The following discussion in the September 2007 journal of The Minerals, Metals & Materials Society, Vol.59, No.9, p.16-20, in an article titled “Artistry, Chemistry, Secrecy,” may help elucidate this distinction:
“[Corning Inc. scientist and Carder Steuben club member Greg Merkel] found that both Tiffany and Carder employed similar techniques to achieve their effects. The key, he said, was to incorporate silver ions dissolved in the glass, subsequently reduce the glass to form metallic silver at the surface, and then spray the glass with a solution of tin salt to form a thin iridescent layer of tin oxide.

“Nash, in his notebooks, reported that the silver surface required heating the glass object, while still on the punty, in the glory hole “with the oil “turned up until the flame appears green.” The effect, he wrote, was “to produce a reducing atmosphere.” The work is plunged in and out of this flame until a silver mirror appears on the surface.” Then, Nash wrote, came the spray with a solution of proto chloride tin, dissolved in water, on the hot glass surface. The method was developed after years of testing, according to Nash.

“’AJN (Arthur J. Nash) made literally thousands of experiments before obtaining a silver luster and then a copper luster. The spray of tin solution turned the silver into a delicate gold or bluish luster.’

“Merkel said the reducing flame ‘would strip oxygen atoms off the surface of the glass. Something in the glass has to change its charge to compensate, and silver is most ready to reduce its charge. The silver precipitates out of the glass as silver metal,’ he said. When the surface is sprayed with the tin solution and reheated multiple times, the mirrorlike surface buckles, he said, forming a kind of matte, satiny surface.

“Merkel said no one is sure who invented the process, but, if it was Arthur Nash, working for Tiffany, Merkel believes he should have patented his iridescent glassmaking technique.”

The mere appearance that the collar of the vase exhibited at the University of Southern Indiana is made of gold Aurene, as compared to the fact that it more realistically was made with blue Aurene, stems in part from the reheating process Dr. Merkel referred to. As evidence of this, consider the first attached photo of another Carder Steuben yellow jade vase with a homogeneous blue Aurene over-casing. Note how the top collar of the vase appears to be more “gold” in appearance as compared to the more predominantly blue foot.

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