Lampworking is a type of glasswork that uses a gas fueled torch to melt rods and tubes of clear and colored glass. Once in a molten state, the glass is formed by blowing and shaping with a variety of tools and hand movements. It is also known as flameworking or torchworking, as the modern practice no longer uses oil-fueled lamps. Although the art form has been practiced since ancient times, it became widely practiced in Murano, Italy 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.

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 or natural gas, or in some countries butane, for the fuel gas, with either air or pure oxygen (which can be produced by an oxygen concentrator) as the oxidizer. It was not until the late 1960s that lampwork became recognized as a serious art form by German born lampwork glass artist Hans Godo Frabel who utilized his scientific glassblowing training to create relatively large pieces of lampwork glass art in borosilicate.

In addition to beads and artwork, lampworking is used to create scientific tools, particularly for chemistry.

Lampworking can be done with many types of glass, but the most common are soda-lime glass, sometimes called "soft glass" - and borosilicate 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.

Different colors of glass must be carefully 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. Different 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.

After designing a piece, a lampworker must carefully 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. 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 can shatter. Once finished the piece must be annealed in an oven to prevent cracking or shattering.

Annealing, 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.

Rod vs. sheet

Most lampworkers use rods 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 glass is usually not used, as it is not formulated for flameworking and there is little variation of color available.

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