The recent November James Julia auction of glass and lamps offered would-be glass collectors an opportunity to view many of these techniques revived in the late 19th and early 20th centuries. The catalog offered a learning experience, with photo examples of such techniques as cameo glass, patte-de-verre and enamelling.
It was the Egyptians and Romans who developed glass coloring into a fine art, along with the technique of adding glass to glass. Such additions are known as glass blobs, prunts and threading.
Another ancient technique, pate de verre (powdered glass made into a paste, then colored and molded) was rediscovered and used in a new way during the Art Nouveau period by the French art glass makers. When these pieces come to auction, prices are in the thousands of dollars.
Molded glass was popular with the Egyptians. What we know today as "Cire perdue" or the "lost wax process," was a process that began with an object modeled in wax, then covered with clay. After the wax melted, and was poured away, the space would be re-filled with molten glass. This process was revived during the Art Nouveau decades.
When the Romans conquered Egypt in 27 B.C. they introduced glass-blowing. By the second century, migrant craftsmen had carried their techniques for the same to the Roman Colonies.
Glass factories had opened by the end of the 1st century in Germany, Belgium and England. While most of the objects were utilitarian, decorative objects were slowly introduced.
Painted glass, involves yet another technique, that is divided into many other categories. Lustre-painting, first used in Egypt, consisted of films of color, painted onto the body of the piece, which turned lustrous when fired.
Enamelling dates back to the 15th century B.C. In this process, colors are fused to the piece by refiring. The enamel is made of a finely powdered metallic coloring agent, mixed with oil, painted on glass and fired.
Cold-painting, is done on glass with lacquer or oil-based pigments and not fired.
Decorating by cutting into the glass with different tools can be traced to 1st century B.C. Roman glass decorators. A rotating wheel or lathe first cut into the glass surface.
This created shallow depressions, facets and grooves. Another method called for the wheel and hand tools to cut into the outermost layer so that the decoration showed in relief. A different effect was achieved by grinding away a solid block of glass to create a high relief design. Intaglio cutting, created and incised, reverse relief effect.
Cut glass was skillfully done in the late 19th to early 20th century by America's top glass houses, such as Libbey.
Would-be-collectors need to seriously study, first hand, if possible, the various techniques and their makers. Be wary of so-called ancient Roman glass objects. They may have been recently made and "fluoresced." Also faked are Daum cameo shades.
Attend auction previews when possible and ask questions.