ACID POLISHING: process where gray cuttings produced by abrasive wheel are smoothed and polished by acid immersion.

AIR BUBBLES: bubbles or seeds that arise when chemicals for making glass are mixed. 

AIR TWIST STEM: effect achieved by entrapping air bubbles in molten glass and stretching it with a twisting motion.

ANNEALING: process where the finished piece is reheated and gradually cooled to provide strength.

BEAD: rounded edge of a tumbler caused when excess glass is burned off.

BENT GLASS: flat pieces of glass reheated and allowed to sag into a decorative curved shape.

BLANK: undecorated piece.

BLOWN GLASS: technique of shaping glass by air pressure, with or without a mold.

BOBECHE: used to hold candlesticks and catch wax.

BOROSILICATE GLASS: glassware composition used in fire-proof and heat-proof glass baking and cooking items. Pyrex is borsilicate glass.

BOWL: the cup of the stemmed glass.

CARVED GLASS: sand-blasted glass where areas take on soft gray color.

CASED GLASS: one layer of glass is applied over another.

COLD PAINTING: decorative technique utilizing lacquer oil-based pigments with no subsequent firing.

COPPER WHEEL ENGRAVING: technique where a decoration is cut by a copper wheel.

CRACKLED WARE: surface is marked by a network of cracks. (Also used in ceramic decoration.)

CRYSTAL: abused term, referring to clear, colorless glass.

CUT GLASS: glass whose surface is decorated with cuttings applied by an abrasive wheel.

DECALCOMANIA: decorative technique of applying color decals of a plastic-like substance that comes off during firing to leave only the pigment on the surface.

ENGRAVING: decorative technique of cutting the surface with wheels or sharp pointed tools by hand.

ETCHING: decoration eaten into the ware by acid.

FACETING: decorative technique of cutting diamond-shaped or other patterns into surface.

FLASHED GLASS: clear glass covered with a thin second layer of colored glass that can be cut to produce various effects similar to cased glass.

FLINT GLASS: glass made of potash and lead oxide.

FOOT: base of the stem.

FROSTED GLASS: semi-opaque glass with a gray-textured surface.

FULL LEAD: glass with high lead content: 24 or 30%, usually.

GRAY CUTTING: glass decoration applied by abrasive wheel that leaves it gray and opaque.

IRIDESCENT GLASS: glass with special coating which, when struck by light, reflects a rainbow.

LACE GLASS: glass decorated with a maze of thread-like lines resembling lace fabric.

MILK GLASS: white opaque glass used mostly in reproduction of early decorative pieces.

MOLD-BLOWN/MOLD-PRESSED: glass manufactured by blowing molten glass into a mold. Mold pressured glass is the result of a mechanized process in which a gob of glass is forced into a mold and plunged into the center to form a hollow section.

OPAL GLASS: colored glass with a fired-on finish that imparts a milky iridescence.

OPTIC: decoration that yields swirls or ripples that are made by forming the glass in a mold.

OVERLAYING: decorative technique in which a second layer is applied to glass to achieve a two-tone effect.

PATTERN GLASS: pressed glassware originally produced in America between 1890 and 1940.

POLISHED CUTTING: glassware design cut by an abrasive wheel and then polished with acid or a buffing wheel.

PONTIL MARK: rough mark on the base made when the pontil (the iron rod used to handle hand-made glass) is removed. A true sign of hand-made, mouth-blown glass.

POTASH GLASS: glass containing potassium carbonate, usually resulting in a thickness suitable to cutting.

PRESSED GLASS: glassware formed in a mold.

ROCK CRYSTAL: quartz-like material resembling solid glass not used because of its rarity and high cost.

SAND BLASTING: or SAND ETCHING: technique in which sand or grit is forced through high pressure to  etch a pattern.

SANDWICH GLASS: early pressed glass from Sandwich, Massachusetts and prized by collectors today.

SCREEN PRINTING: decoration where stencil-like screens are used to apply colors.

SEAM: a ride on a piece of glass caused by the minute crack between two parts of the mold. Same as a mold mark.

SEEDS: small pieces of the glass batch which do not completely melt during the glass-making process.

SHAM BOTTOM: heavy solid base on tumblers to add weight and point up clarity or color of the glass.

SILVER DEPOSIT: decoration in which silver is bonded to the glass.

SODA LIME: same as lime glass. Not as brilliant as lead glass. Most widely produced type of glass.

STAINED GLASS: in tableware, glass that has been sprayed with a colored stain and then fired to fuse to the surface.

TANK: furnace used to make glass.

TEMPER: process used to increase the strength of glass by reheating it after its formed and then rapidly cooling.