owens888, spongiform, and I took a glass flameworking class at The Crucible. In flameworking you burn propane with oxygen (from a gas cylinder, not just the O2 in the air) to heat glass tubing and rods to thousands of degrees, melt them into blobs of color and pattern, and shape these blobs into marbles, pendants, figurines, vessels, and paper weights. It was much fun. Class ran 10a-6p Saturday and Sunday (a so-called "intensive" session) during which we three, and four other students, were taught by two glass faculty (Jay Bridgland and Tara Murray). The faculty to student ratio is great: we each had lots of attention from the instructors and we could easily get questions answered. Much of the time was free flameworking time, during which we could work on anything we wanted, with breaks for instruction and demonstrations of several fundamentals. From memory, these are my notes:Safety: the flame is 5500F. Don't touch. Really; not even for a split second. Glass is hot, too. Burn salves and bandaids are in the first aid kit. If you blow glass too thinly then blow it out, it will turn into a fine glass dust that's pretty bad to inhale. Don't do this. If you do, Tara will water spritz the space above your work area to reduce the floating glass, then make you clean everything up.
Melting glass. Always rotate glass in the flame, to keep the heat even across the piece. Uneven heat causes things to bend and slump in unattractive ways. When you're working on a piece of glass you may need a handle on the end. This is called a punty. Heat the end of the punty and the glass, touch the two together outside the flame, wait a moment, and you're done - handle'd. To cut glass, heat it in the flame, and either (a) pull it apart in the flame, briskly, or (b) rotate the two pieces apart from each other like bicycle pedals, winding up the extra glass as you go. Do this in the flame.
Gravity marble. Attach a punty to a 5/8" rod stock. Flame cut the thick glass 2-3" from the punty. Begin heating the end and rolling the punty for even heat. This glass will become slumpy soft and begin to ball up. Move the heat along toward the punty, building up the ball. Too egglike? Hold the punty down. Too mushroom-like? Hold the punty up. Use gravity as your free tool, your third hand. Eventually, you have a ball. Make a cold seal: let the ball cool a little, heat another punty, then just touch it to the other side of the ball. It's a cold seal b/c the work is colder than the punty. Don't worry, it'll hold. Now, flame cut the original punty off right at the end of the ball. You can remove extra glass: heat, touch a cold punty to the hot glass out of the flame, pull, then flame cut the thin strands left. Repeat. With the extra glass removed, continue shaping the marble, using gravity to assist. Do not get the flame on the cold seal. When you're done, set the marble in the graphite mold, just so the marble doesn't roll. Hold the punty up, tap it with a tool near the seal, and it should come right off. Heat the marble side of the seal to smooth out any flat lump left by the cold seal, and you're done. Don't touch the marble, it's still hot.
The torch. The torch has two hoses and two knobs, one for propane (on top, in red) and one for oxygen (side, green or silver). The propane is the first gas on and the last gas off -- don't ever run the oxygen without propane. A little propane, flint spark to light, then add oxygen. You can make three types of flame: neutral, reducing (more propane than oxygen; not all the propane burns), and oxidizing (more oxygen than propane; hotter).
More, next post.
