Definitions of:   stretch glass - struck glass - threading - Tiffany glass - Tiffany glass fakes and forgeries -
vaseline glass - Victorian glass - vintage glass - whimsey

GLOSSARY OF GLASS TERMS

Str - Z

 A - B      Ca - Cz      D - E       F - L       M - Op       Ov - Pe       Pi - Pz       Q - R      Sa - Ste

Glossary Table of Contents
   

The purpose of this guide is to help buyers understand terms
commonly used by E-Bay sellers to describe old American glass (1850-1930).
Please leave feedback by pushing the button at the bottom of the page.

Many thanks to all the E-Bayers who
have contributed photos to this glossary!

Detail of onion-skin surface of stretch glass
photo courtesy of  lan5

Stretch glass:  a category of glass.  Stretch glass is characterized by soft iridescence and often has an onion-skin surface.  The glass may have stretch marks or a satin finish, and generally shows no pattern or very little pattern.  Stretch glass is made by pressing or blowing molten glass into a mold; next, the glass is removed and, while still hot, sprayed with metallic salts to give it surface iridescence; the glass is then reheated and "worked" a little like pie dough -- it is crimped or flared out or cupped inward.  Working the glass stretches the iridescent surface, creating the onion-skin effect.  Vintage stretch glass was manufactured in the United States between 1916 and the early 1930's, by nine companies:  Central, Diamond Glass-Ware, Fenton, Imperial, Jeannette, Lancaster, Northwood, U.S. Glass and Vineland Flint.   The footed bowl below is an example of Northwood's blue "Rainbow Ware," a variety of stretch glass that the company began making in 1916.  If you're interested in learning more about stretch glass, or need help in identifying pieces, we recommend that you look at the website of The Stretch Glass Society (stretchglasssociety.org), and at shetlarglass.com.  Additional examples of stretch glass can be found in our guide on Fenton's Topaz Stretch Glass .

A Northwood stretch glass footed bowl, circa 1916-1935
photo by *treasurehunter*

Struck glass:  striking is a glass-making technique.  Striking is defined in An Illustrated Dictionary of Glass as "the process of reheating glass after it has cooled, in order to develop a color or a opacifying agent".  Striking is a technique used in making heat sensitive glass such as gold ruby, Burmese, Peachblow and amberina glass.  All four of these types of glass contain gold chloride.  When the glass is molten, gold chloride is added.  The glass is allowed to cool, and then reheated.  The gold chloride content causes those parts of the glass that reach a specified temperature to take on a pink or red tone.  Making gold ruby, for example, requires a temperature of about 1300 degrees Fahrenheit, held for four hours.  If the glass is heated at too high a temperature, it turns brown, and if heated for too short a period, a purple rather than red tint results.  The process of striking glass correctly requires great skill, and heat-sensitive glasses such as gold ruby and Burmese are considered among the most difficult to work with and to produce.  Selenium ruby glass, and selenium-based amberina such as that used in Fenton carnival glass, are other examples of heat sensitive glass.  Both are made by a process similar to that described above:  a cadmium-selenium compound is added to molten glass, which is then cooled and then reheated to produce red glass with an orange cast.   See "amberina", "Burmese glass,"  "Peachblow" and "ruby glass" in this glossary. 

Swung Glass:  see "pulled glass" in this glossary.

Threading is a thin trail of glass wound around a glass object
to create the appearance of parallel lines
photo by curculiosglass

Threading.  threading is a glass-making technique.  The Corning Museum of Glass defines threading as "the process of winding a thin trail of glass around an object to create the appearance of parallel lines".  A "trail" is a strand of glass.  In 1876, W.J. Hodgetts of Stourbridge, England, patented a machine that produced closely-spaced glass threading; such threading is shown in the photographic detail of a threaded vase immediately above.  An Illustrated Dictionary of Glass notes that the term "threading" may be used in an additional sense, to refer to the process of drawing glass threads through molten glass as a means of decorating it with a design such as a zig-zag pattern.  The term "trailing" is sometimes used interchangeably with "threading".

      

An Art Nouveau Tiffany Favrile peacock-feather vase (left),
with a detail photo showing the exquisite texture
and iridescence of Tiffany's Favrile.

photo permission metmuseum.org

Tiffany glass:  Louis Comfort Tiffany (1848-1933) was a New York glass designer.  He first adapted the Art Nouveau style to glass in 1894, and his name has become synonymous with the Art Nouveau movement in America.  (See Art Nouveau in this glossary.)   Harold Newman's An Illustrated Dictionary of Glass defines "Tiffany glass" as "Glassware in a vast variety of forms and styles made by the successive companies of Louis Comfort Tiffany.  The ware, mostly in Art Nouveau style, was of colored cased glass and iridescent glass."  Newman writes that Tiffany glass was rarely enameled; instead, Tiffany sought to decorate his glassware through "the shape, texture and colors of the glassware itself and the luster finish".  Tiffany's best known pieces were his Favrile vases, which are prized for their soft and exquisitely textured iridescence.  According to Judith Miller, author of Twentieth Century Glass, Tiffany's Favrile glass was characterized by vibrant colors, often in shades of blue and gold; incorporated botanical Art Nouveau forms; and included such ware as vases with simplified peacock-feather designs (shown above), gooseneck vases, floriform vases with gently flared ruffled rims, and Jack-in the-pulpit vases.  An Illustrated Dictionary of Glass notes that all Favrile vases were signed with Tiffany's name or initials.  The name "Favrile," which appears on the bases of Favrile glassware, was registered in 1894 and is derived from the old English fabrile meaning "belonging to a craftsman or his craft".   Similar glassmakers:  Favrile was imitated by early 20th-century American glassworks such as Quezal and Durand (See "Quezal" and "Durand" in this glossary.)  Vases marketed under the name "Favrile" also have been issued by contemporary glass-makers.   Recommended resources on Tiffany glass:  If you wish to view genuine Tiffany glassware, including Favrile vases, we recommend the website of the Metropolitan Museum of Art (metmuseum.org/explore/Tiffany/menu.html).   Special Note:   Buyers should note that Favrile vases with forged Tiffany signatures and/or forged paper labels abound; please read information on Tiffany fakes and forgeries below. 

This paper label bearing the "L.C.T." monogram is a Tiffany forgery.
The label, made with black ink on white paper, is hand-cut with slightly irregular edges.
It is about the right size (3/4" in diameter).  Nevertheless, the label, which appears on an
unsigned vase and hides a rough pontil, fluoresces under a black light and is a forgery.

Tiffany glass fakes and forgeries:   E-Bay buyers should note that deceptive imitations of Tiffany glassware bearing forged signatures and fake paper labels are very common.  All genuine Favrile ware was signed -- and so, of course, any clever fake will be signed, too.  On genuine Tiffany Favrile vases, the signatures are engraved and usually are found in or around ground pontils.  Forged Tiffany marks, signatures and labels appear in many guises, according to Mark Chervenka, whose Guide to Fakes & Reproductions, 4th ed. (2007) bears helpful photographs of ingeniously faked Louis Tiffany signatures.  Like Tiffany's original glassware, forgeries may be signed with the initials L.C.T., the full name "L.C. Tiffany," and/or additional information such as false date marks and the annotation "Favrile".  Forged paper labels, imitating original Tiffany paper labels, are prevalent and simple to make using home computers and image-editing software.  Chervenka notes that the following are hallmarks of forgeries.  (1) Internal swirls and flaws are visible when glassware is held to a light.  (2) acid-etched "Tiffany" signatures or marks -- original Tiffany marks were not acid etched; they were engraved, and all acid-etched Tiffany marks are fake.  (Original Favrile vases were rotary-engraved; very rarely, on later ware such as Tiffany's pastel pieces, signatures were made with a diamond-tipped stylus.)  (3) Large lettering in forged signatures -- engraved words and numbers on the bases of  genuine Tiffany pieces are rarely taller than 1/4" and usually closer to 1/8" in height.  (4)  Open or rough pontils are usually a sign of forgery.  With very limited exceptions, pontils on genuine Tiffany vases are almost always ground  (see "pontil" in this glossary).  (5)  Forged paper "Tiffany" labels may have one or some of the following characteristics:  labels appear without an accompanying signature; are larger than 3/4" in diameter; fluoresce under a black light; or have poorly formed letters. (See above photo for example of a forged label.)  About Tiffany lamps:  This guide focusses on glassware, and thus Tiffany lamps and windows are outside of its general scope.  Buyers should note, however, that original Tiffany lamps were made by Tiffany Studios; Tiffany died in 1933, and all production of all Tiffany glass ended in 1938.  Companies such as "Dale Tiffany," "Meyda Tiffany" and "Robert Louis Tiffany" produce Tiffany imitations.  Many of their products are sold on E-Bay; while often quite appealing, they should not be confused with true Tiffany lamps and stained-glass windows -- which may run into the hundreds of thousands of dollars, and which thus often appear in museums and not on E-Bay.  Resources on forged Tiffany:  Prospective Tiffany glass buyers may find it helpful to familiarize themselves with watchdog Internet sites, such as Tiffany Fakes, which keep track of forged or misattributed Tiffany glassware sold on E-Bay and elsewhere.  (See, e.g., tiffanyfakes.com/index.htm and see ginforsodditiques.com/tiffanyfakes.html).  Much glassware sold as Tiffany Favrile on E-Bay is Bohemian glass that has been marred with forged signatures -- which is a shame, because old Bohemian glass is of historic value and is beautiful in its own right; information on Art Nouveau Bohemian glass can be found at Loetz.com.   Please note:   Listings that appear advertised in the right-hand margin of this glossary under the heading "Items from E-Bay Sellers" are posted by E-Bay, are not part of this glossary and may offer fake as well as genuine Tiffany glass.

Uranium Glass:  See "vaseline glass" below. 

This Victorian canary opalescent Twigs vase was made by Northwood in 1898.
Vaseline or canary glass is greenish yellow, as shown at left.
Under ultraviolet light, the glass glows bright green (right).

photo courtesy of 1912antiques

Vaseline Glass:  a category of glass.  Vaseline glass is yellow or greenish-yellow glass that contains uranium dioxide as a colorant, which makes the glass fluoresce (glow) bright green under an ultraviolet or "black" light.  Vaseline glass is a broad category that cuts across other glass categories:  it encompasses glass manufactured from 1835 onward and includes non-opaque glass, whether pressed or hand blown, made in a variety of forms such as transparent, opalescent, stretch, satin, cut and cased glass.  According to David A. Peterson, author of Vaseline Glass:  from Canary to Contemporary, the first vaseline glass was produced in 1835 by Bohemian glassmaker Joseph Riedel, who divided uranium-content glass into "Annagelb" (yellow) and "Annagrun" (yellow-green) varieties.  American glass companies began producing vaseline glass in 1840, and most high-quality American vaseline glass predates the late 1930's.  In 1942, following the advent of World War II, the United States government curtailed the liberal use of uranium by glassworks.  (In 1959, the ban was lifted, and since then companies such as Imperial, Fenton, Fostoria, Mosser, Summit, Boyd and Pairpoint have issued contemporary uranium-content vaseline glass.)  There is some disagreement among aficionados about what constitutes true vaseline glass.  The paramount vaseline glass organization, Vaseline Glass Collectors, Inc., holds that to be true "vaseline glass,"  glass must contain at least 2% uranium dioxide; be yellow or yellow-green by daylight; glow green under ultraviolet light; and be non-opaque.  The VGCI excludes these four kinds of glass from the category, although all contain uranium and glow green under a blacklight:  green Depression glass; yellowish-white custard glass, which is opaque; pink-and-yellow Burmese glass, which is also opaque; and fluorescent green and teal-colored glass.  Nevertheless, much glass advertised as "vaseline" glass on E-Bay is fluorescent green Depression glass.  Other names:  "Canary glass" is the name that glass makers called vaseline glass in the 1800's and the early 1900's:  thus, in listings for Victorian Era pieces, you'll see vaseline glass described as "canary" or "canary opalescent".   The British glass company, Davidson, used the terms "Primrose Pearline" and "Lemon Pearline" to describe its canary glass, and the term "lemonescent" is occasionally used to describe canary glass as well.  From 1920 onward, the Fenton Art Glass Company called its opalescent vaseline glass "Topaz" opalescent.   To complicate matters further, the British sometimes use the term "vaseline glass" differently from Americans.  In Great Britain, "vaseline" is  synonymous with "opalescent," and the preferred term for glass that contains uranium oxide is "uranium glass".  This name, however, is much broader in scope than the American "vaseline glass".  The term "uranium glass" encompasses any glass that contains uranium in any form;  for example, Sue Davis, author of Pictorial Guide to Vaseline Glass, uses the term to include vaseline glass, transparent and opalescent green uranium-content glass, and custard and Burmese glass.  When searching on E-Bay for vaseline glass, it's a good idea to plug three terms - vaseline, canary and uranium -- into the E-Bay search engine.  Please take note:  E-Bay sellers occasionally claim that glass that glows purple under a black light is "vaseline glass" -- this is an error.  Many white objects, including clean cotton undershirts, can glow purple under UV light.  Uranium-content glass fluoresces green.  If you're interested in learning more about vaseline glass, we recommend the website of Vaseline Glass Collectors, Inc. (vaselineglass.org).  Further information on vaseline glass also can be found in our guides on fluorescent glass.

Queen Victoria's rule extended from 1837-1901.
Victorian glass made during this period includes such categories
of American glass as early American pattern glass (EAPG),
American Brilliant Period cut-glass (ABP glass), American
Victorian art glass and 19th Century cranberry glass. 

Victorian glass:  The Victorian Era is the period of Queen Victoria's rule, from 1837 to 1901.  Many categories of American glass are referred to as "Victorian glass".  For example, you will find sellers using the terms "Victorian art glass" or "Victorian milk glass" or "Victorian custard glass"  when describing glassware made from the mid-1800's through as late as 1910.  American Brilliant Period glass (ABP glass), 19th Century American cranberry glass and early American pattern glass (EAPG) are all kinds of Victorian glass.  The Northwood Twigs vase shown above under "vaseline glass" is an example of Victorian opalescent pressed glass.

Vintage glass:  a very general, and often subjective category of glass.  "Vintage" is a term that means many different things to different people, and so you'll see this word used with contradictory meanings on E-Bay.  The primary definition of "vintage" in the American Heritage Dictionary is, simply, "old".  The Random House Unabridged Dictionary defines "vintage" a little more precisely, as "representing the high quality of a past time".  Both meanings are used by E-Bay sellers.  Many use "vintage" loosely and subjectively, to convey simply that a piece is "old".  Our favorite definition of "vintage," however, is from a veteran E-Bay seller and fairly similar to the usage embraced by the Random House Unabridged Dictionary:  "Vintage glass is glass manufactured at a specific place and time as a representation of the essence and style of that specific place and time."  Thus, for example, if "carnival glass" is defined as iridescent glass made from 1907 through the 1920's, a piece of carnival glass from that period is "vintage carnival".  A piece of iridescent glass manufactured in the 1980's, however, would not be "vintage carnival".  E-Bay defines "vintage" in yet another way -- in delineating glass sale categories, E-Bay limits the category "vintage glass" to glass made before 1940.

  

A Fenton Reverse Drapery bowl, circa 1908, and a vase whimsey
shaped from the same mold:  both have a 3 1/4-inch base.
photos courtesy of curculiosglass

Whimsey.  Pressed glass pieces like the bowl featured above left were made from metal molds.  Most pressed glass pieces made in a given mold were shaped into a predestined form -- that is, the pieces formed in bowl molds were destined to be bowls, while those shaped in dish molds were destined to be dishes, and so forth. Whimseys were glass pieces that were stretched and formed into a novel shape after being removed from the mold.  For example, the Reverse Drapery whimsey vase at above right was pulled from a bowl mold used to make the bowl at left.  Traditionally, whimseys are thought of as pieces that the individual glassworker made for himself as a display of his special skill or inventiveness, and which he intended to slip home with at the end of the work day.  Some whimsey shapes are one-of-a kind, while others became so popular that they went into limited production and were marketed directly by glass works.  Whimseys are sometimes referred to as "friggers," or as "end-of-day glass".

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            Many thanks to E-Bayers  1912antiques,  lan5 and  *treasurehunter*  for generously contributing their expertise and photographs to this page of the glass glossary.  Rights to all photos belong to the photographers, and pictures should not be used without their permission.  Text is (c) 2007 curculiosglass, all rights reserved.  To locate any E-Bay seller mentioned here,  just click on "Site Map" at the bottom of your E-Bay screen, and then click on "Feedback Forum" at the right top corner of the large menu that pops up.  Type or copy the seller's name into the Feedback Forum's search blank. 

           If you found this guide helpful, please leave feedback on the guide by pressing on the button below -- this helps the guide rise in the review index, so that buyers can find it more easily.   To read our guides on carnival and opalescent glass, click on GUIDE INDEX.