Glossary of Glass Terms

Whether you have long been a glass collector and have hundreds of pieces or you’re just becoming a glass enthusiast, it’s useful to know some of the commonly used, sometimes confusing, terms in the glassmaking industry.

So, we’ve put together this A to Z glossary of glass terms, which will help define for you many of the terms frequently found in glass collector’s books, web sites, eBay and other online auction listings!

If you have other terms you think should be added or any here you believe should be changed, updated or expanded, please contact us or feel free to leave your additions as comments.

Acid Etching – process of cutting a design into glass using acid as the cutting agent. The pattern to be etched is transferred from an etching plate to the surface of the glass with an acid resist made of beeswax. The vessel is then exposed to hydrofluoric acid or acid fumes, which etch the unprotected surface areas, thus leaving a frosted design when the protective layer is removed. Some companies used a metal etching plate rather than a resist to protect the areas that were to remain unaffected.

Acid Finish – matte finish produced by exposing surface of a glass piece to acid fumes during finishing or, in some cases, with a mechanical grinding wheel (also see Satin).

Amberina – glass piece shaded from red at the top to amber at the base, produced by cooling and reheating the top portion of the piece.

Annealing – moving glass on a conveyor belt through a hot chamber and then a cooling tunnel to gradually cool hot glass and prevent stress fractures and breaking.

Applied – attaching a handle or other piece of molten glass to a glass vessel by hand, most commonly in hand or mold blown glass techniques, but also in early pressed glass pieces.

Appliquéd Glass – decorative glass featuring three-dimensional glass trim, applied to a piece by hand in a molten state after the piece itself has cooled, often in fruit or flowering vine patterns.

Aventurine – copper or other metal oxides suspended between a clear outer layer and colored inner casing of glass, forming crystals that reflect light, giving a glass object a shimmering appearance.

AOP or All Over Pattern – differentiation of Depression glass pieces within the same pattern but which have variations. An example would be a dish or tumbler with an AOP instead of just a decorative band on the rim.

Batch – a batch of materials used to form glass pieces, with silica, potash and soda ash being the primary ingredients used in glassmaking.

Butter Pat or Chip – small round or square dish used to hold butter on a Victorian table, only a few were produced in glass, notable cut glass.

Cameo Glass – ancient Roman technique, revived in England in the 19th century, using multi-layers of glass, with an opaque white outer surface carved by hand or acid etching to create designs by exposing the colored inner layer.

Cane – glass rod used in glassmaking to produce effects like stripes or twisted filigree.

Cased Glass – two layers of contrasting glass fused together, creating a single piece, with the inner layer sometimes blown into the outer layer, or a piece of one color dipped into molten glass another color while still hot. Cameo is one form of cased glass.

Cast Figure Mold – process perfected by Reuben Haley and used to create his unique Martele hand wrought glassware; a glass mold is cast from a sculpted model to transfer fine details without additional milling.

Chip Mold – glass mold technique in which a pattern is cut or chipped with hammer and chisel into an iron mold’s surface.

Chop Plate – a large, flat serving plate, also sometimes called a salver.

Cobalt – a very dark blue color produced by adding cobalt to a batch.

Comport or Compote – a small, open-bowl candy dish with a stem and base.

Console Set – a matched set usually containing a center bowl and a pair of candlesticks, popular in the 1920s and 30s, either mold blown or pressed.

Cracker Jar or Biscuit Jar – Victorian era equivalent of a modern day cookie jar, made with glass or china, usually barrel shaped, with a silver plate rim, cover and bail handle.

Crackle, Crackled or Craquelle – also called Iced Glass, a mold or hand blown glass object, while hot, is plunged into cold water before blowing to produce a finely crackled outer surface and smooth interior.

Cranberry – transparent, reddish-pink color of glass, produced by adding gold oxide to a batch, originated in the 1820s and popular through the 1880s.

Crimping – decorative ruffle or ribbon design around the rim of a vase or bowl, achieved by manipulating the shape with a tool while the piece is still hot.

Custard Glass – an opaque milk glass variation in colors varying from rich, creamy yellow to bone white with an opalescent finish; Uranium salts were added to batches used to produce antique custard glass, so that it will trigger a Geiger counter needle to move and also glows under a black light.

Domino Tray – named for the Domino Sugar Company, produced by Depression glassware makers in the later 1920s and 30s; a round tray with center ring designed to hold a creamer sugar cubes.

Enameled Decoration – decorative glass technique commonly used in Victorian art glass, hand painting glass decorative technique using white or colored enamel paints applied on a finished glass piece and re fired to bake the enamel finish.

Epergne – 19th century glass vessel with a tall, trumpeted vase fitted into a wide, shallow bowl base, foot or pedestal.

Etched Mold – glass mold technique with pattern etched into the surface, achieving very fine detail in pressed glass.

Etching – patterns or designs cut into glass either by acid etching or needle etching techniques.

Fired On – applying color to the surface of a glass piece, then baking it to permanently fuse the color to the piece.

Fire Polishing – technique in which glass is reheated to smooth mold seams without distorting the pattern on a mold blown or pressed glass piece.

Flashed On – highlighting crystal glass with colored stain, commonly amber or red, by reheating the piece to fuse or flash the color to the surface of the piece, tends to rub off more easily with use than color which is fired on.

Frog – fitted into a bowl or the neck of a vase, a Frog is a heavy glass disc with holes designed to hold a flower arrangement; Figural Frogs have a figurine in the center.

Gather – using a punty rod or blowpipe, a glassblower “gathers” molten glass on the end of the rod or pipe.

Grill Plate – popular in diners and grills in the 1920s and 30s; a plate with raised ridges dividing it into three sections to separate food.

Handkerchief Vase – style of 20th century Venetian glass vase with the sides pulled up and pleated into interesting shapes, giving it the appearance of a handkerchief.

Hot Metal Man – also called a Batch Man or Color Man, supervises the mixing of glass batches and formulates the recipes, which are often the hallmark of a glass company.

Iridescence – a type of multi-hued or rainbow colored finish which is achieved by spraying metal salts onto hot glass and then re-firing the piece.

Ice Lip – fold that is molded around the lip of a pitcher, preventing ice from pouring into a glass along with the water, iced tea or other liquid.

Jack-in-the-Pulpit Vase – a style of vase made to look like the flower by manipulating the rim to curl the back edge upward and the front edge downward.

Knop – refers to a knob or finial on the lid of a glass vessel or the bulbous part of the stem on a wineglass or goblet.

Lampwork or Lampworking – using a torch or small flame, called a lamp, to form delicate glass objects from canes.

Latticino – Italian term that refers to a technique developed by the Romans and used in Murano glassmaking in which spiraled threads of white or colored glass are embedded into a piece of clear crystal.

Lattimo – Italian term, meaning latte milk, refers to opaque white or milk glass.

Milk Glass – opaque white glass; early milk glass pieces are opalescent when held up to a light source.

Millefiori – meaning “thousand flowers” in Italian and also called Tessera, or tile work; a technique in which glass rods are cut into discs and placed into a mold to form a decorative pattern, then re-fired to fuse the pieces together.

Mold or Mould – a pattern is made using wood or plaster and used to produce a rough iron cast in a metal foundry, into which molten glass can then be poured to produce glass molded pieces, milled and shaped, and then the design etched or cut into the surface.

Mold Blown – molten glass is blown into a mold to produce a glass object with the pattern of the mold.

Mold Pressed or Press Molded – molten glass is poured into a mold, and then a plunger presses glass into the mold evenly to produce a glass object.

Murano Glass – refers to glass made in Murano, Italy or elsewhere using techniques like hand blowing and many others developed or refined over the centuries by glassmakers in Murano.

Nappy – refers to a bowl.

Needle Etching – technique developed in the 20th century; a hand held or mechanical needle is used to draw fine and sometimes ornate, repetitive designs on a glass piece.

Novelty – a small scale glass version of some larger object, like an animal, sword, ship, etc. and popular in the late 19th century as boxes, toothpick holders and similar items.

Opal – 19th century term; refers to what we now call milk glass.

Opalescent – meaning semi-translucent, refers to white colored glass that shows some orange or “fire” translucence when held up to a direct light source, usually around the edges of the piece, flowing into a different color of glass.

Ormolu – refers to decorative metal added to an object made of glass.

Overshot – achieved by rolling a gather over a steel plate on which small glass particles are placed, reheating the object to melt the sharp edges of these fragments, and then blowing the object to its final size and form, giving the object a rough texture and nicely speckled color.

Piedouche – French term referring to a paperweight which is raised up on a pedestal foot.

Pontil Mark – refers to the place on the base of a glass object where it is attached to the punty rod or pontil while the blower is shaping and finishing the piece, and then snapped off and polished smooth.

Punty Rod or Pontil Rod – refers to the metal rod a glassmaker attaches to hot glass so that it can be handled while hot as the piece is shaped and finished.

Rigaree – a form of appliquéd glass decoration in a crimped, a ribbon-like highlight on some Victorian art glass pieces.

Rose Bowl – popular 19th century bowl with edges curved inward and a small center opening, typically tri-footed and used to display small rosebuds or potpourri of rose petals.

Ruby Glass – refers to transparent, dark red colored glass.

Salver – also called a chop plate; serving plate, typically 11 to 13 inches in diameter, without handles.

Satin – refers to acid finish; use of hydrofluoric acid to produce a velvety, smooth glass surface.

Scalloping – refers to decorative ruffles or wavy shape given to the rim of bowls, vases and other glass items during the molding process versus crimping, which is hand done after molding.

Serrated – refers to a notched or sawtooth edge on the rim of a glass piece, usually found on cut glass pieces.

Shop – refers to a glassmaking crew that works together, hand making glass items and glass art pieces.

Silver Deposit or Silver Overlay – complex glassmaking technique that uses electrolysis to deposit a metallic silver design painted on a glass piece with a wash of borax, oxide of lead, sand, nitrate of potash, white arsenic and phosphate of lime mixed in turpentine, the piece is then fired, submerged in an electroplating bath to deposit the silver, and finally buffed and polished.

Sickness – refers to cloudy stains in glass vessels such as vases, decanters and bottles, caused by chemical reactions inside the vessel when liquid is left in it for a long period; can sometimes be cleaned or may required re-polishing the piece.

Spall – A shallow rounded flake on a glass object, generally near the rim of a piece.

Spatter – similar to Overshot, a technique producing spotted or multi-colored glass with white inner casing and clear outer casing by rolling a gather in tiny particles of glass; Spatter is cased, resulting in a smooth surface, whereas Overshot glass is left rough and uneven.

Stemware – refers to a drinking vessel with a bowl set on a slender pedestal or base with a stem.

Teardrop – refers to an inclusion caused by an air bubble, purposely created in a glass item for decorative effect to highlight a feature such as the stem of a goblet or the stopper of a decanter.

Tumble Up – long necked glass bottle that was often placed on a nightstand, having a small, upside-down tumbler seated on top so that the tumbler was used both as a stopper and drinking vessel.

Turn – refers to a shift worked by a shop and measuring output by how many pieces were produced rather than the number of hours worked.

Vesica – refers to a decorative, pointed oval design cut into a glass piece.

Water Set – a set of tableware containing a large pitcher and six or more goblets or tumblers, and sometimes also including a matched tray.

Whimsey – also known as Lunchpail Pieces, whimsies are pieces created by glassmakers as special gifts for loved ones or close friends, with special or unique features, rarely sold on the open market and fetching extremely high prices from collectors attracted to the work of a given shop.