When I was young, I used to irritate my father by throwing pennies into the fireplace to see if they would melt. Of course they didn't; a normal hearth fire isn't nearly hot enough to melt copper or any other metal used for coins. But the tremendous heat that can be generated by electrical currents, lasers, and burning gases can melt metal. Many techniques employed in the craft of welding use that kind of heat to take metal and plastic pieces apart or to bond them together. If you're mechanically inclined, you like assembling and disassembling things, you're physically fit with no back problems, and enjoy the thought of being within a few inches of temperatures in excess of 1000 degrees Fahrenheit, you might want to think about studying welding, either as a career or as a useful skill to have.

Welding is a process in which metal parts are joined by melting their surfaces together. This creates much stronger bonds than bolts, glue, etc., and if it's done right, the bond is impermeable to air and water and other fluids. To make a standard weld, you apply enough heat to liquefy the matching surfaces of parts you want to join and introduce molten filler material to fill the gap between them. The materials will flow into each other and then resolidify. (It's very important to have a "barrier" to keep oxygen out of the joint, so that it doesn't oxidize and weaken. Some welding processes use an antioxidant coating on the filler called a "flux" as a barrier; others form a barrier by surrounding the welding point with a chemically nonreactive gas.) Welding is extremely important to many industrial processes, including construction and the manufacture of metallic equipment. In particular, vehicle assembly -- whether the vehicle is a car, ship, plane, or space shuttle -- depends on it.

A number of companies will teach you welding as part of their on-the-job training, but you can study welding in many other places too.

• Some traditional colleges and universities, especially community colleges, have welding courses that you can take as part of a certificate or degree program. Examples include Anne Arundel Community College in Maryland; Tennessee Tech University, which teaches welding technology and advanced welding as part of their industrial technology program; Ohio State University, which has a welding engineering program; and Ferris State University in Michigan, which confers associate and bachelor's degrees through the teaching of their Welding Engineering Technology Department.
• Welding is one of many specialized courses of study available at career schools such as Vatterott College (with campuses throughout the midwest) and Texas State Technical College; you can receive diplomas and certificates (and sometimes degrees) from these schools.
• You can learn the trade at a dedicated welding school such as the Lincoln Electric Welding School in Ohio; Cal-Trade Welding School in California; the Missouri Welding Institute; GRB College of Welding in Alberta, Canada; or the New Zealand Welding School with several campuses in that country. (Texas State Technical College maintains a good list of links to welding schools, career information, and other resources.)
• There are also welding specialty schools. For example, Plastic Welding School in Portsmouth, RI, offers certification in the welding of plastics, and Divers Academy International in Camden, NJ, will train you in the difficult but rewarding field of underwater welding.

Here are some of the different techniques you might learn if you study welding.

• Gas welding burns a gas such as hydrogen or acetylene to melt a flux-coated filler rod and the surfaces being welded. It's an older, dated technology, but is still used in low-end applications.
• Basic arc welding creates a high-temperature electrical arc to melt the flux-coated filler rod and surfaces. This is probably the most widely used welding method today.
• Metal inert gas (MIG) welding also relies on electrical arcs, but does away with flux coatings, which can produce toxic fumes. Instead, a spool of filler-metal wire is fed into the weld, and oxygen is kept out with a barrier of relatively nonreactive gas such as carbon dioxide or argon. Tungsten inert gas (TIG) welding is similar, but uses a tungsten electrode for very fine control; it can be used to weld very thin metal pieces and challenging materials such as stainless steel.
• Resistance welding, widely used in car manufacturing and repair, calls for connecting electrodes to overlapping surfaces that you want to weld and running electric power through them; the materials resist the current, causing them to heat up (in the same way a light-bulb filament does) until they melt together.
• Laser welding uses beams of extremely hot laser light to melt the surfaces being welded (or even momentarily boil them, for deep weld penetration). Because the laser light can be passed through fiberoptic cable, it can be aimed flexibly and yet very precisely. Laser welding is usually done with robots or automated equipment rather than manually, but you can learn to operate the machines that do it.
• Electron-beam welding is much like laser welding, but uses beams of electrons rather than light. It doesn't require a barrier because it's done in a vacuum chamber. The process is normally automated, but you can learn to run the machines.
• The various types of pressure welding use pressure rather than externally applied heat to join surfaces. Cold-press welding simply crushes parts together at such amazing pressures that the materials deform and fuse. Friction welding rotates one part against another at high speed; the parts join at much lower pressures than the cold-press process. Ultrasonic welding joins surfaces by bombarding them with ultrasonic vibrations, which requires even less pressure.
• Brazing is similar to welding, but only the filler is melted, not the work surface, to produce bonds that don't need to be as strong as welds.
• When only relatively weak bonds are required, soldering can do the job. Again, only the filler is melted, at even lower temperatures than brazing requires.
• Where welding, brazing, and soldering join things, cutting separates pieces from each other by melting or vaporizing thin slices between them. This is most often done with "plasma cutters," torches that use an electric arc to turn a stream of air into superhot ionized plasma.

According to the U.S. Department of Labor's Bureau of Labor Statistics, 521,000 people were employed in the U.S. in welding, soldering, and brazing jobs in the year 2000. Three-quarters of those jobs were in either manufacturing (most involving transportation equipment, industrial machinery, and metal fabrication) and services (mostly for repair shops and as contracted temp welders). Note that welding-related jobs will sometimes require heavy lifting, as well as working in unusual positions or cramped spaces in order to reach the area you're welding; many employers now insist that candidates have a full back X-ray done prior to hiring, for their protection and yours. Nevertheless, a welding-school education can help prepare you for lots of interesting careers, including:

• Welders join and cut whatever their employer requires, be it on a factory floor, in an aircraft hangar, or against the piling of an oil platform 200 feet below the ocean surface.
• Welding-machine operators work with robots and other automated welding equipment: maintaining it, configuring it for the requirements of different jobs, or even programming it.
• Machinists use many welding tools and techniques to machine (shape, grind, polish, etc.) metal and plastic parts.
• Machine assemblers put together engines and other complex mechanisms using welds and whatever other methods are required.
• Tool & die makers use welding and machining to create the special tools and dies (molds) that will be required for factory production of custom parts.
• Pipefitters join and seal pipe and pipeline sections to within extremely close tolerances; this is extremely important when the pipes need to carry high-pressure or hazardous fluids.
• Boilermakers do a lot of welding as they mount, install, move, and maintain boilers, vats, and other industrial containers over their decades-long service lifetimes (and you thought somebody made up the nickname of the Purdue Boilermakers sports teams...)
• Metalsmiths use some welding tools and techniques to form precious metals such as gold and silver into jewelry, decorative art, or more useful implements.
• Metallurgists work with metals and alloys in order to solve problems such as, "We want to use alloys X and Y for this product. Can they be welded? If so, what's the best way to do it? If not, what materials or joining process can we substitute?"

It's been estimated that over 50% of the gross national product of the world's developed countries is associated in some way with welded or bonded products. If you want to be one of the people who provides this vital service, step up and turn on the heat...or the light, or the ultrasound. A welding education will teach you how to harness these forces and use them well.