Engraving. The process of cutting a design into the surface of glass, either with a diamond, metal needle, or other sharp implement (including sand) or with a rotating wheel (Newman 1977, p. 107; Wilson 1994, p. 43).
Wheel Engraving. The process of decorating the surface of glass with pictorial or formal decorations or inscriptions by the grinding action wheels. Stone-wheel engraving, which is basically the same technique as that used in glass cutting and smoothing, uses a water-wet stone wheel and no abrasive mixture. Copper-wheel engraving, on the other hand, applies a mixture of oil and emery or oil and Carborumdum to its wheels which may be made of metals other than copper. (Newman 1977, p. 340; Wilson 1994, p. 43).
The following account of the copper-wheel engraving process is taken from an article, “The Dorflingers’ Contribution to the White House Glass,” written by David J. Dorflinger and published in The Acorn, Vol. 9, p. 42 . It concisely summarizes the engraver’s technique, in this case as applied to a set of tableware cut in the Russian patttern that was first ordered from C. Dorflinger & Sons in 1891, during the administration of President Benjamin Harrison. The seal referred to is a variation of the Great Seal of the United States which was engraved on each piece.
The engraving of the seal utilizes the use of a bench-mounted lathe with interchangeable spindles that have wheels made of copper mounted on the ends. These wheels vary in shape and size with diameters ranging from one-eighth to four inches. An engraver might have as many as 100 different size and shape wheels on hand to perform his artistry. Since the copper wheel cannot cut glass, an abrasive mixture of emery or corundum mixed with a light oil is applied to the wheel. The mixture abrades the surface of the glass and leaves a very fine gray finish that becomes part of the desired pattern. The engraver has to apply this mixture with a tiny brush or even his finger, and has to repeat the process after about 30 seconds. During that time every detail is painstakingly cut. In the case of the White House Seal, that would include the eagle’s plumage, arrows, olive branch, and motto, all executed in miniature. Each seal took an average of six hours to complete. The skill of the craftsman and the enormity of the task is best appreciated when the details are examined with a high-powered magnifying glass. [Good examples of the engraved seal can be found in Spillman (1989, p. 37) and (1996, p. 238). – JMH]
Intaglio Engraving. “The style of decoration created by engraving or cutting below the surface of the glass so that the apparent elevations of the design are hollowed out and an impression from the design yields an image in relief. The background is not cut away, but is left in the plane of the highest areas of the design.” (Newman 1977, p. 159) A lathe, equipped with small stone wheels, is used. For a more complete explanation, please see the “British Intaglio” section in the Engraving 6 file.
Acid Etching. “A chemical process using hydrofluoric acid (alone or in combination with sulphuric acid) to remove varying amounts of glass from the surface of an object. Depending on the type of glass, acid strength, the length of exposure, and the process (whether the glass is exposed to the fumes of the acid or is immersed in it), different surface textures are obtained, ranging from smooth to textured or frosted. Decorative patterns, often imitating [wheel] engraving, are achieved by applying an acid resist such as wax or asphaltum [bituminous hydrocarbon] to protect the surface that is to remain clear and then scratching through it to permit the acid to attack the unprotected surface. … Deeply etched decorations can be achieved by repeating applications of resist and exposures to the acid. Such decorations, often called acid cutback, appear on many vases designed by Frederick Carder at Steuben.” (Wilson 1994, p. 43)
Some References (Articles)
Dorflinger, D. J., 1996: The engraver: an addendum — copper vs. stone, The Hobstar, Vol. 19, No. 2, pp. 1, 6-7 (Oct 1996).
Farrar, E. S., 1977: The master engravers of Corning, New York, The Magazine Antiques, Oct 1977, pp. 726-31.
Fauster, C. U., 1975: Vaupel engraved masterpieces acquired by major museums, The Glass Club Bulletin, No. 113, pp. 1, 3-7 (Aug 1975).
Ferland, Donald, 1995/6: Elegant simplicity as created by Louis Friedrich Vaupel, master copper-wheel glass engraver, The Acorn, Vol. 6, pp. 91-116.
Fuchs, B. B. (editor), 1998: On the cover [Stevens and Williams “rock crystal”], The Glass Club Bulletin, No. 183, cover and p. 3 (fall 1998).
Kohut, John, 2004: Donated to ACGA: historically significant copper wheel lathe, The Hobstar, Vol. 27, No. 4, cover and pp. 4422-30.
Nicholson, Robin, 2003: Engraved Jacobite glasses, The Magazine Antiques, June 2003, pp. 80-85.
Rakow, J. K. and L. S. Rakow, 1991: Stuart and Sons’ cameo and English rock-crystal-cut glass, The Magazine Antiques, Feb 1991, pp. 382-7.