The Charles Hosmer - Morse Museum of American Art


Secrets of Tiffany Glassmaking

Ongoing

Louis Comfort Tiffany (1848–1933) began his work in glass with the same tools and ingredients that had been used by artisans for thousands of years before him. Tiffany took the science of glassmaking, however, and elevated it to an art form of new brilliance and beauty. Under his watch, teams of talented designers and craftspeople translated Tiffany’s all-encompassing vision into some of the most memorable glass creations of our time. Tiffany’s studio system was not a simple enterprise; he needed specialized employees—a hierarchy of artists and artisans—to accomplish his goals. This exhibition, updated and reinstalled on September 4, 2012, addresses the processes that Tiffany’s many companies used to produce everything from glass mosaics and molded buttons to leaded-glass lamps and windows.

Silica (most commonly sand), soda or potash, and lime are the three primary ingredients of glass. When mixed, these raw materials form what artisans refer to as batch. Color is created in various ways, but often by adding either metallic oxides to the batch or various ready-made forms of colored glass during other stages of the glassmaking process.

Blown Glass

Glassblowing is a team activity that employs the talents of many artisans. Typically, a supervisor known as a gaffer manages a group of seven people who comprise one shop. To create a blown-glass object, glass ingredients must first be heated to a molten state of 2,400 degrees Fahrenheit. These are the next steps:

Shaping: An artisan collects a gob of the hot, liquified glass, known as a gather, from the working furnace on the end of a metal blowpipe, a hollow rod, usually five-feet long. The molten glass is blown, rolled, pulled, and manipulated with various tools into the shape desired. During this phase, the object is taken frequently to a reheating furnace commonly referred to as a glory hole.

Finishing: The shaped object is transferred from the blowpipe to a pontil, a long, solid metal rod, for additional sculpting and added details.

Cooling: The completed glass object must be placed in an annealing oven to cool gradually over time. If glass objects are not annealed, they will crack or break.

Opalescent Glass

The glass made at Tiffany Studios was called opalescent glass or American glass. It was radically different from pot metal, a type of glass commonly used in Tiffany’s era. Pot metal was uniformly colored, translucent, and regular in every way. Craftspeople making pot metal windows often painted them with enamels—a glass paste—to create form and visual effects.

By contrast, opalescent glass was fabulously varied in color and texture—even within a single piece of glass. By careful selection, Tiffany could use his glass to mimic foliage, fabric, water, or a sunlit horizon. Tiffany, in a sense, was painting with glass, as opposed to painting on glass. He applied for and received patents for his modifications and improvements upon opalescent glass, although John La Farge (1835–1910) first patented the underlying process in 1879.

Tiffany used the word Favrile as a general trademark for his glass—and later for his pottery and metalwork. Favrile and “fabricate” have the same root, and Tiffany applied the name to his glass to suggest its handmade quality.

Tiffany glass was created in a variety of ways. Some glass pieces were cast in molds. Other types were rolled out onto a flat surface and manipulated. To create the cloth-like drapery glass artisans used hand tools to move and twist hot glass into folds. Mixing two or more colors of molten glass together created streaky or striated glass. Confetti glass was made by pouring molten glass on top of pieces of colored glass or by sprinkling pieces of colored glass into hot glass. Some of these terms for glass types are merely descriptive and were not necessarily used by Tiffany.

Leaded-glass Windows

The creation of a Tiffany stained-glass window began with a small sketch or drawing that was followed by a cartoon, a full-scale painting of the proposed window. Then the designer made two cutlines—tracings of the cartoon on which the planned glass cuts were carefully marked in thick black line. The first cutline served as the pattern for the window assembly. The second was cut into templates to be used to produce the many individual glass shapes and sizes required by the pattern. Next, glass for the window design was chosen from the thousands of colors and textures that were stored and coded in sheets. Once all of the glass for the window was selected and cut, the window was put together in one of two ways:

Leaded-glass technique: Artisans fit the cut glass into flexible lead cames, which are strips of lead shaped like construction “I-beams.” The glass pieces are placed on either side of the “I” and soldered and mitered at the joints.

Copper-foil technique: Lead cames were difficult to use for complex patterns requiring many small glass pieces. For these projects, especially the leaded-glass lampshades, artisans wrapped the edges of glass pieces with a thin copper foil before they were laid out and soldered together. This copper foil was treated with beeswax on one side and muriatic acid on the other. The beeswax permitted the foil to adhere to the glass, while the muriatic acid permitted solder to bond to the foil.

Leaded-glass Lampshades

The creation of a leaded-glass lampshade began with a color sketch on paper of the lamp design. Next, the design was copied using pencil, watercolor, and paint onto a plaster form in the shape of the shade so that it could be assessed as a three-dimensional object. The design was finally inscribed on a wooden form. Patterns for each individual piece of glass that made up the shade were created using the design on this mold, and the leaded-glass shade was assembled on it.

Standardization and bottom-line concerns governed lamps production. Often the patterns were fashioned out of brass, which lasted longer than other materials and could be used multiple times in filling orders for the same lampshade design.

When beginning the shade’s assembly, a brass ring was placed on top of the wood mold to create an aperture. The artisan then wrapped selected glass pieces—each cut using the brass patterns—in copper foil and positioned them on the mold with small nails. Starting at the top and working down, glass pieces were soldered first to the aperture ring and then one by one to each other. When this process was finished, the shade was removed from the mold and turned upside down to add a rim to the bottom edge and stabilize the shape. The shade was then soldered on the inside and “beaded” on the outside. Beading is a heavier application of solder to smooth and round out the line and to protect the copper-foiled edges. After soldering, the shade was patinated to change the color of the solder lines.

The design and production of lampshades was primarily accomplished within the Women’s Glass Cutting Department. Tiffany established the department at his studio in 1892, allowing women for the first time to cut and select glass for windows and mosaics along with the men. Tiffany employed six women at his glasshouse in Corona, New York, in 1892. By 1897, Tiffany had between forty and fifty young women employed in his glass workshop.

Clara Driscoll (1861–1944), supervisor of the department, designed many lampshades including the popular Dragonfly & Water shade that was awarded a medal at the 1900 Paris world’s fair.

 

RESOURCES:

  • Vase
  • Vase, 1905
  • This blown glass vessel was most likely created in two parts. The stemmed vessel and the foot would have been joined together while hot.
  • Vase
  • Vase, c. 1906-13.
  • This blown glass vase features colors that may have been applied with frit or glass rods.
  • Vase
  • Vase, c. 1898.
  • Tiffany’s Cypriote glass has the rough, irregular, and pitted surface, that was common in glass buried for centuries. Tiffany artisans likely reproduced this effect by rolling molten glass in crushed glass crumbs.
  • Tea stand
  • Tea stand, c. 1901.
  • Tiffany began experimenting with mosaics in the early 1870s. The glass pieces used for mosaics, often about one-quarter-inch square, are called tessarae and are cut from sheets of colored glass. This stand was designed by Clara Driscoll (1861–1944).
  • Tiffany Studios workshop
  • Tiffany Studios workshop, c. 1927.
  • Photograph from the collection of The Charles Hosmer Morse Museum of American Art.
  • Workers in the Tiffany Lamp Department
  • Workers in the Tiffany Lamp Department, c. 1898.
  • Photograph from Cosmopolitan, 1899.