Lampworking (otherwise known as flame working and torch working) is a form of glassblowing which uses a compressed gas fuelled torch to melt tubes and rods of coloured and clear glass. When the glass is heated , it is then formed by blowing and shaping using tools and moving the glass in the hands. The art form has been practiced since ancient Syrian (1st Century BC) and was practiced in Italy in the 14th Century. Lampworking became popular primarily in France in the mid 19th Century where lampworking technique was extended to the production of paper weights.
In the early days, lampworking was done in the flame of an oil lamp, and air was blown into the flame by the artist to create the heat necessary to work the glass. In modern day torches, LPG or natural gas, and in some countries butane is burnt with air or oxygen to create the temperatures needed.
Lampworking is used to create sculpture, scientific apparatus, lighting, beads, wine glasses and all manner of functional and artistic glassware.
Lampworking can be done with a variety of different types of glass, the most common being soda-lime glass (soft glass) and borosilicate glass, often called hard glass. Leaded glass was used to manufacture neon signs though its use has faded due to health and environmental concerns.
The properties of soft glass are somewhat different than the properties of hard glass in that a soft glass will melt at lower temperatures and does not react well to temperature changes unlike borosilicate glass. Soft glass is more prone to cracking when cooling or being worked because it has what is known as a higher coefficient of expansion, than that of borosilicate glass.
Borosilicate glass is more forgiving to work, as its coefficient of expansion is lower and less likely to crack when heating and cooling. The nature of borosilicate allows it to be applied to so many different applications, making it a very versatile material to work with.