05 / 03

Back to the Basics

Close up shows eggplant shaped multi-colored glass at an early stage that will be heated, expanded and worked into final shape. Photo, Denis Paiste, Materials Processing Center

Back to the Basics – Glass Vocabulary

New to the world of glass? Need a refresher on terminology? The Corning Museum of Glass  has a thorough dictionary of all things glass. This post will cover selected basic terminology including tools and fundamental techniques.

Lino has openly shared that no matter how creative of an artist you may be, you must get the basics right to produce great work.

Back when Lino conducted a master class for MIT Glass Lab instructors, he shared the following information with Denis Paiste of the Materials Processing Center: “A half-hour to an hour of concentration on these few basic things can help you realize where you are making mistakes, Taglipietra says. Holding the pipe too close, for example, is a mistake that can result in someone getting burned if someone bumps you. ‘You must move in the correct way,’ he says. ‘The balance, how you move it, you want kind of an elegant movement.'”

Lino at MIT

 

Bit

A mass of molten glass, usually small and freshly gathered from the furnace. In a team of glassworkers, the bit gatherer removes bits from the furnace, using a bit iron. Bits are also known as gobs.

Blowing

The technique of forming an object by inflating a gather or gob of molten glass on the end of a blowpipe. Traditionally and in modern furnace working, the gaffer blows through the tube, slightly inflating the gob, which is then manipulated into the required form by swinging it, rolling it on a marver, or shaping it with tools or in a mold. It is then inflated to the desired size. In flameworking, one end of the glass tube is heated and closed immediately, after which the worker blows into the other end and manipulates the hot glass.

Blowpipe

An iron or steel tube, usually four to five feet long, for blowing glass. Blowpipes have a mouthpiece at one end and are usually fitted at the other end with a metal ring that helps to retain the gather.

Clapper

A tool consisting of two rectangular pieces of wood joined at one end by a leather hinge. There is an aperture in one of the pieces of wood, and this holds the stem of a goblet or wineglass while it is being made. The clapper is used to squeeze a blob of glass in order to form the foot.

Cold Working

The collective term for the many techniques (such as copper-wheel engraving and cutting) used to alter or decorate glass when it is cold.

Dip Mold

A cylindrical or truncated conical one-piece mold with a patterned interior. The mold is open at the top so that a parison can be dipped into it and then inflated. It is also known as an optic mold.

Firing

The process of (1) heating the batch in order to fuse it into glass by exposing it to the required temperature in a crucible or pot, (2) reheating unfinished glassware while it is being worked, or (3) reheating glassware in a muffle to fuse enamel or gilding. The melting of the batch may require a temperature of about 2400°-2750°F (1300°-1500°C), whereas the muffle kiln may require a temperature of only about 950°- 1300°F (500°-700°C).

Frit

Batch ingredients such as sand and alkali, which have been partly reacted by heating but not completely melted. After cooling, frit is ground to a powder and melted. Fritting (or sintering) is the process of making frit.

Furnace

An enclosed structure for the production and application of heat. In glassmaking, furnaces are used for melting the batch, maintaining pots of glass in a molten state, and reheating partly formed objects at the glory hole.

Gaffer

The master craftsman in charge of a chair, or team, of hot-glass workers.

Gather

(Noun) A mass of molten glass (sometimes called a gob) collected on the end of a blowpipe, pontil, or gathering iron; (verb) to collect molten glass on the end of a tool.

Glory Hole

A hole in the side of a glass furnace, used to reheat glass that is being fashioned or decorated; a separate appliance for reheating glass.

Marver

A smooth, flat surface on which softened glass is rolled, when attached to a blowpipe or pontil, in order to smooth it or to consolidate applied decoration. (Verb) To roll softened glass on a marver.

Parison

A gather, on the end of a blowpipe, that is already partly inflated.

Pontil

The pontil, or punty, is a solid metal rod that is usually tipped with a wad of hot glass, then applied to the base of a vessel to hold it during manufacture. It often leaves an irregular or ring-shaped scar on the base when removed. This is called the “pontil mark.”

Shears

A tool used to trim excess hot glass from an object in the course of production. Many modern shears are embedded with chips of industrial diamonds.

Slumping

The process of reheating a blank until it becomes soft and gradually flows under its own weight over or into a former mold and eventually assumes the shape of the mold. Soda-lime glass becomes soft at about 1110°F (600°C).

Tool

Any instrument used by glassworkers to develop and shape an object. Glassworkers’ tools include the blowpipe, pontil, gathering iron, jacks, shears, clapper, pallet, block, pincers, battledore, lipper, and crimper.