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How?... Flameworking, also known as lampworking, originated in Italy and is now worldwide like most everything. The basic concept is that the flameworker heats glass rods to melting temperature over a torch flame, molds them while hot and malleable, and then lets them cool and harden. Of course, it's not that simple. The torch flame that heats the glass is most commonly made from oxygen and propane. Some flameworkers use a "Hot Head" torch which uses only propane. The air is fed in through holes in the torch head. This torch has very limited settings and low heat, but is much cheaper. Glass is a very interesting medium and as it heats up and cools down it changes in mass. That means that when it is hot, it is a different size than when it is cool. Each glass has a different Coefficient of Expansion (COE) that determines exactly how much it expands when heated. If a glass of COE 33 is heated and mixed with a glass that is COE 104, upon cooling one will shrink more than the other and they will crack apart. The good news is that glass manufacturers all over the world have addressed this problem years ago. Glass is sold by the COE and there are a few standard ones. COE 104 glass is an extremely common one and is referred to as "soft glass" or "soda glass" because it both melts at a low temperature and is made with soda lime. COE 33 glass is also common and is known as "boro" which stands for borosilicate. Again, borosilicate is the substance used to create the glass (this glass is also known as Pyrex). Glass is available in other COE's like 90 and 96, however I use primarily 33 and 104. Now you might be wondering that if I heat up the end of a glass rod in the torch flame, why doesn't the heat difference between the tip and the rest of the rod make the tip crack off? The answer is, it does! Glass (especially soft glass) has to be eased into the flame to prevent the glass from popping off. A common mistake is to bring a thick rod of soft glass into the flame too quickly, which causes numerous flakes of glass to pop off the end of the rod. This is very uncomfortable to the flameworker because it's both very startling and it hurts when hot glass shards hit ones hand at high speeds. When the glass cools down, it cools very unevenly. A blob of glass (known as a gather) will cool from the outside to the inside in a regular environment. This causes stress in the glass, and something that cools unevenly like this will break very easily. To remove the stress in the glass, there is a process called annealing. The hot glass is placed into a kiln that is set to a certain temperature. As the glass sits inside the kiln, the temperature across the whole piece becomes the same. At this point, there is no stress, but the glass is still about 1000 degrees F. Kilns are extremely insulated, so when the flameworker turns the kiln off, or turns it to a lower setting, the time it takes for the kiln to cool off allows the glass pieces to cool very slowly. When they cool very slowly, the inside cools at about the same speed as the outside which leaves no stress in the glass. The glass used gets shipped in long rods, each about 6-7mm in diameter. The rods vary in color and transparency and each is labelled as to what COE it is and what color it is. In addition to glass, there are numerous tools used to model the glass. Tweezers are standard, shears are often helpful with sculptural things, graphite paddles are common (graphite will not combust, will not stick to the glass, and is a very poor heat sink so will not cool the glass very fast). This is all well and good, except the flameworker is dealing with glass at thousands of degrees, tanks of highly explosive gas, and of course, a very fragile and often sharp medium. There are many safety things to think about, but perhaps the most important one is eye protection. I'm not talking about shards of glass, it is important to protect against that too, but flameworkers wear special glasses that block the intense sodium flame. When glass burns it excites the sodium which is an extremely bright orange color in the flame and can damage ones eyes. The glasses cancel all light coming from that source protecting the wearer. If you would like to start doing this, I'd be happy to help out any way I can, this is a very basic description and I probably forgot half the things that should have been put in here. Feel free to email me if you have any other questions or if I left out something important. |