Lampworking
Encyclopedia
Murano
Murano is a series of islands linked by bridges in the Venetian Lagoon, northern Italy. It lies about 1.5 km north of Venice and measures about across with a population of just over 5,000 . It is famous for its glass making, particularly lampworking...
, Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
in the 14th century. In the mid 19th century lampwork technique was extended to the production of paperweights, primarily in France, where it became a popular art form, still collected today. Lampworking differs from glassblowing in that glassblowing uses a blowpipe to inflate a glass blob known as a gob or gather, whereas lampworking manipulates glass either by the use of tools, gravity, or by blowing directly into the end of a glass tube.
Early lampworking was done in the flame of an oil lamp, with the artist blowing air into the flame through a pipe. Most artists today use torches that burn either propane
Propane
Propane is a three-carbon alkane with the molecular formula , normally a gas, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used as a fuel for engines, oxy-gas torches, barbecues, portable stoves, and residential central...
or natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
, or in some countries butane
Butane
Butane is a gas with the formula C4H10 that is an alkane with four carbon atoms. The term may refer to any of two structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, butane refers only to the unbranched n-butane isomer; the other one being called "methylpropane" or...
, for the fuel gas, with either air or pure oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
(which can be produced by an oxygen concentrator
Oxygen concentrator
An oxygen concentrator is a device providing oxygen therapy to a patient at minimally to substantially higher concentrations than available in ambient air. They are used as a safer, less expensive, and more convenient alternative to tanks of compressed oxygen. Common models retail at around US$800...
) as the oxidizer. Many hobbyists use MAPP gas
MAPP gas
MAPP gas is a trademarked name belonging to Linde Group, previously to Dow, for a fuel gas based on a stabilized mixture of methylacetylene and propadiene. The name comes from the original chemical composition: methylacetylene-propadiene propane...
in portable canisters for fuel.
Lampworking is used to create artwork, including figurines, trinkets, curios, Christmas tree ornaments, beads and much more. It is also used to create scientific instruments as well as glass models of animal and botanical subjects.
Glass selection
Lampworking can be done with many types of glassGlass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
, but the most common are soda-lime glass
Soda-lime glass
Soda-lime glass, also called soda-lime-silica glass, is the most prevalent type of glass, used for windowpanes, and glass containers for beverages, food, and some commodity items...
, sometimes called "soft glass," and borosilicate glass
Borosilicate glass
Borosilicate glass is a type of glass with the main glass-forming constituents silica and boron oxide. Borosilicate glasses are known for having very low coefficients of thermal expansion , making them resistant to thermal shock, more so than any other common glass...
, often called "hard glass." Leaded glass tubing was commonly used in the manufacture of neon signs, although its use has been fading due to environmental concerns and health risks.
Soft glass is sometimes useful because it melts at lower temperatures, however it does not react well to temperature changes like borosilicate glass does. Because soft glass expands a lot more than hard glass when heated, and contracts more when cooled, along with its brittle nature, during cooling or even while working it, soft glass is more prone to cracking due to thermal shock than borosilicate. If a piece cools too quickly in one spot, such as if cold water touches a thin piece of soft glass, that part would solidify immediately, and cause a crack. However, hard glass or borosilicate, would be more resilient. Borosilicate is just like regular glass, SiO2 , but it has a more flexible molecular structure from being doped with boron.
The colors of the glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
must be selected for compatibility with each other, both chemically (more of a concern with soft glass than borosilicate) and in terms of coefficient of thermal expansion (COE) [CTE is also used for Coefficient of Thermal Expansion.] Glass with incompatible COE, mixed together, can create powerful stresses within a finished piece as it cools, cracking or violently shattering the piece. Major types of glass, e.g., borosilicate and soda-lime glass, are not compatible with each other. Chemically, some colors can react with each other when melted together. This may cause desirable effects in coloration, metallic sheen, or result in an aesthetically pleasing "web effect". It also can cause undesirable effects such as unattractive discoloration, bubbling, or devitrification.
Borosilicate glass is considered more forgiving to work with, as its lower COE makes it less apt to crack during flameworking than soda-lime glass. However, it has a narrower working temperature range than soda-lime glass, has fewer available colors, and is considerably more expensive. Also, its working range is at higher temperatures than soda-lime glass, requiring larger torches and the use of oxygen instead of air. In addition to producing a hotter flame, the use of pure oxygen allows more control over the flame's oxidizing or reducing properties, which is necessary because some coloring chemicals in borosilicate glass react with any remaining oxygen in the flame either to produce the desired final color or to discolor if extra oxygen is present.
Tools
Tools for lampworking are similar to those used in glassblowingGlassblowing
Glassblowing is a glassforming technique that involves inflating molten glass into a bubble, or parison, with the aid of a blowpipe, or blow tube...
. Marvers - flat surfaces used to roll glass upon in order to shape, smooth or consolidate applied decoration, typically made of graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
or steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
, rods, and other shapes are used to marver or shape the glass. Brass
Brass
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.In comparison, bronze is principally an alloy of copper and tin...
, graphite, or wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
en molds (usually of apple or cherry wood) can be used to mold the hot glass. Tungsten
Tungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
picks can be used to drag glass around on the surface, or to bore a hole through a piece. Steel jacks, usually coated with beeswax
Beeswax
Beeswax is a natural wax produced in the bee hive of honey bees of the genus Apis. It is mainly esters of fatty acids and various long chain alcohols...
, are used to neck down or cut off a piece. The importance of graphite in glassblowing is due to its very low density and thus its ability to absorb heat, this allows the graphite to touch the molten glass with minimal temperature contrast between the metal and glass. The graphite absorbs the heat energy so there is minimal shock to the glass, which is the ultimate goal. There is a wide array of glass blowing tools made of graphite for this reason.
General methods of beadmaking
After designing a piece, a lampworker must plan how to construct it. Once ready to begin, the lampworker slowly introduces glass rod or tubing into the flame to prevent cracking from thermal shock. The glass is heated until molten, wound around a specially-coated steel mandrel, forming the base bead. The coating is an anti-fluxing bead release that will allow the bead to be easily removed from the mandrel. It can then be embellished or decorated using a variety of techniques and materials. All parts of the workpiece must be kept at similar temperatures lest they shatter. Once finished the piece must be annealed in an oven to prevent cracking or shattering.Annealing
Annealing (glass)
Annealing is a process of slowly cooling glass to relieve internal stresses after it was formed. The process may be carried out in a temperature-controlled kiln known as a Lehr. Glass which has not been annealed is liable to crack or shatter when subjected to a relatively small temperature change...
, in glass terms, is heating a piece until its temperature reaches a stress-relief point, that is, a temperature at which the glass is still too hard to deform, but is soft enough for internal stresses to ease. The piece is then allowed to heat-soak until its temperature is uniform throughout. The time necessary for this depends on the type of glass and thickness of the thickest section. The piece is then slowly cooled at a predetermined rate until its temperature is below a critical point, at which it can't generate internal stresses, and then can safely be dropped to room temperature. This relieves the internal stresses, resulting in a piece which should last for many years. Glass which has not been annealed may crack or shatter due to a seemingly minor temperature change or other shock.
Types of Glass
Rod vs. sheetMost lampworkers use rod
Rod (geometry)
In geometry, a rod is a three-dimensional, solid cylinder....
s of glass 7–8 mm in diameter, though pre-made stringers are available in 1–3 mm sizes, or rods of 15 mm or more. Sheet glass can be cut with tools into strips, though it is easier to manipulate if attached to a rod first. Glass is also available in particles of various sizes (frit or powder), which is typically used for surface decorations in lampworked beads. Many manufacturers who once only sold their glass in sheet or very thick rod now provide rods for lampworking use. Window
Window
A window is a transparent or translucent opening in a wall or door that allows the passage of light and, if not closed or sealed, air and sound. Windows are usually glazed or covered in some other transparent or translucent material like float glass. Windows are held in place by frames, which...
glass is usually not used, as it is not formulated for flameworking and there is little variation of color available.
Soda lime glass
The most popular glass for lampworking is soda-lime glass, which is available pre-colored. Soda-lime glass is the traditional mix used in blown furnace glass, and lampworking glass rods were originally hand-drawn from the furnace and allowed to cool for use by lampworkers. Today soda-lime, or "soft" glass is manufactured globally, including Italy, Germany, Czech Republic, China and America.
Lead
In addition to soda lime glass, lampworkers can use lead glass
Lead glass
Lead glass is a variety of glass in which lead replaces the calcium content of a typical potash glass. Lead glass contains typically 18–40 weight% lead oxide , while modern lead crystal, historically also known as flint glass due to the original silica source, contains a minimum of 24% PbO...
. Lead glasses are distinguished by their lower viscosity, heavier weight, and somewhat greater tolerance for COE mismatches.
Borosilicate
Lampworkers can use borosilicate glass, a very hard glass requiring greater heat. Borosilicate originated as laboratory glass, but it is now available in color to the studio artist as a result of a number of new colored borosilicate companies. At one time, soft (soda lime and lead) and hard (borosilicate) glasses had distinctly different looking palettes, but demand by soft-glass artists for the silver strike colors, and the development of the bright, cadmium based `crayon colors' by Glass Alchemy in the boro line, has diminished the distinctions between them.
Basic "Wound Bead" technique
- Preparing the mandrel - The beadmaker starts by dipping a mandrelMandrelA mandrel is one of the following:* an object used to shape machined work.* a tool component that grips or clamps materials to be machined.* a tool component that can be used to grip other moving tool components.- Variants :...
, or wire (stainless steel welding wire, cut into lengths) into a clay based substance (commonly referred to as "bead release") and letting it dry.
- Heating rod and mandrel - The flameworker selects rods of glass to heat in the flame of the torchTorchA torch is a fire source, usually a rod-shaped piece of wood with a rag soaked in pitch and/or some other flammable material wrapped around one end. Torches were often supported in sconces by brackets high up on walls, to throw light over corridors in stone structures such as castles or crypts...
. When both glass and mandrel are sufficiently warm, the beadmaker starts rotating the mandrel while allowing the glass to wind upon it.
- Shaping the bead - Beads are shaped using a combination of heat, gravity and tools such as graphite paddles, mashers, tweezers, and picks. Presses to create shapes and indent patterns into the glass are also used.
- Decorating the bead - Beads can be decorated by melting stringers, or fibers of glass on the surface, creating dots or lines. With a sharp pointed tool, feathers, hearts or other designs may be produced. Metal decorations of copper, silver, gold, palladium and platinum are applied as metal leaf, wire, mesh or fuming.
- Striking - If silver based colors are used (striking colors), the bead must be heated for a few moments in the torch flame or kiln to allow crystals to reform in the glass. This temperature is slightly above the stress relief point.
- Annealing - Once completed, beads should be heated to 940º-1050°F (depending on glass type), until the piece reaches its "stress relief point", held at that temp for a short time, then slowly cooled to avoid thermal shock.
- Cold working - The cooled bead can be further decorated. Standard cold working techniques can be employed such as sandblasting, faceting and polishing. Etching the finished piece with acid leaves a matte finish.
Additional techniques for lampworked beads
Beads can be sandblasted, or they can be faceted, using lapidaryLapidary
A lapidary is an artist or artisan who forms stone, mineral, gemstones, and other suitably durable materials into decorative items such as engraved gems, including cameos, or cabochons, and faceted designs...
techniques. "Furnace glass" beads, more elaborate versions of the old seed bead technique described above, are also being made. Chevron bead
Chevron bead
Chevron beads are special glass beads, the first specimens of this type were created by glass bead makers in Venice and Murano, Italy, towards the end of the 14th century. They may also be referred to as Rosetta, or star beads...
s are multi-layer beads once exclusively made using hot-shop techniques to produce the original tubing; but now some lampworkers make similar designs on their torches before lapping the ends to reveal the various layered colors. As torches get bigger and more powerful, the cross-over between lampworking and furnace glass continues to increase.
Fuming is a technique that has been developed in the past 15 years and was popularized by Bob Snodgrass. Fuming consists of heating silver or gold in the flame, so that the metals vaporize or "fume" microscopically thin layers of particles onto the glass. These particle stick to the hot glass surface changing its color with interesting effects. Silver turns clear glass into a yellowish color, giving shades of blues and greens when backed with a dark color, while gold turns clear glass shades of pinks and reds. The precious metal coating becomes increasingly visible the more the glass is fumed.
Brief history of modern lampworked beads
Lampworked beads (with the exception of Asian and African beadmaking) have generally been the provenance of Italian, and, later, Bohemian lampworkers for the last four hundred years or so who kept the techniques secret. Thirty or so years ago, some American artists started experimenting with the form. Their early efforts, by today's standards, were crude, as there was almost no documentation, and none of the modern tools. However, they shared their information, and some of them started small businesses developing tools, torches and other equipment.This group eventually formed the basis for the International Society of Glass Beadmakers.