Metal workers, jewelers, electronics technicians and roofers are all familiar with solder, a metal alloy with a low melting point that can be used to fuse two other pieces of metal. The soldering tools of choice for melting solder in these trades are a soldering iron, a soldering gun and a soldering pencil. These are basically handheld electric devices with pointed, heated tips. Plumbers also use solder to fuse copper pipes, but they usually use a torch, which heats a wider area more quickly than a soldering iron.
The composition of solder depends on the application. Tin is the prime component of the solder used in the electronics industry, while the solder jewelers use contains a large percentage of silver. Lead has traditionally been a primary component of solder, but because it constitutes a health hazard, it has largely been eliminated from solder used by plumbers, electronics technicians and home hobbyists. Roofers and sheet metal workers still use solder that contains equal amounts of lead and tin, however. It's known as 50-50 solder.
Because of its accuracy and the fact that it won't ignite materials around the joint being soldered, a soldering iron has more applications than a torch. Here's a list of 10 uses for a soldering iron, soldering gun or soldering pen.
Soldering in the Roofing Trades
Roofers use solder to fuse galvanized metal for flashing. They also use it to fuse components of copper roofs. Because accuracy is less important than it is in other trades, roofing soldering irons have broad tips that heat up quickly and the ability to retain heat in windy conditions. To this end, they're often gas-assisted.
Soldering Metal Gutters
If your home has metal gutters, the sections were joined by soldering. The tools and materials are similar to the ones roofers use to join metal flashing pieces. The solder joint is leakproof and permanent.
Soldering Stained Glass and Mosaics
Stained glass workers have traditionally used lead solder, but these days lead-free solders are more common for making stained glass windows and mosaic sculptures. The basic tool you need for this is a 100-watt soldering iron. Other supplies include safety glasses, a glass cutter, pliers, a glass grinder, copper tape and a solid wood work surface.
Using Soldering Tools for Circuit Boards
Solder guarantees contact between two wires to establish electrical continuity. In addition, solder "locks" the wiring down to the circuit board. Because solder joints are typically small, it's common to use a soldering pencil hooked up to a power station that allows the user to control the temperature.
Soldering for Electricians
Because it guarantees electrical continuity, electricians often use solder to splice wires when doing residential or commercial wiring. The also sometimes use solder to fuse wires to electrical terminals inside electrical devices or on control panels.
Solder in Auto Repair
Solder isn't strong enough to make engine repairs but is used to fill irregular cavities, smooth rough surfaces and tighten joints. It's also used to tin the edges of metal sheets, fill up holes and fuse metal panels when doing auto body repair.
Soldering Tools for Home Projects
Soldering pencils, guns and irons that are adequate for home use are made in abundance. Most are heated electrically and have tips that can be used with a propane torch. The proper tool depends on the project, but tasks like joining wires and circuit-board repairs may call for varying amounts of heat or more control. As with other soldering projects, tool tips must be kept clean at all times.
Soldering in the Jewelry Trades
Jewelers use soldering pens and soldering irons with interchangeable tips, and they also use accurate torches that burn propane or butane. The solder has a high percentage of silver, and jewelers typically use borax flux to reduce the metal oxides that form when you apply heat to metal. Flux is an important component of any soldering job.
Soldering Vacuum Tubes
Inexpensive vacuum switch tubes are soldered to form a sealant and to insulate housing parts in metal to ceramic connections. For example, copper parts can be soft-soldered to ceramic without risking the tube. Silver tin solder is placed on a pre-fab vacuum switch tube to form a corrugated ring with a cover that forms a tight vacuum on the circuitry board to which the tube is attached.
Uses of Soldering Tools in Plumbing
Plumbers use led-free solder to join copper plumbing pipes. Although they usually do this with a torch, there are instances of working in tight quarters when a soldering iron is safer. They'll typically use a roofer's soldering iron or a soldering gun, which heats up quickly when the trigger is depressed.
Chris Deziel is a contractor, builder and general fix-it pro who has been active in the construction trades for 40 years. He has degrees in science and humanities and years of teaching experience. An avid craftsman and musician, Deziel began writing on home improvement topics in 2010. He worked as an expert consultant with eHow Now and Pro Referral -- a Home Depot site. A DIYer by nature, Deziel regularly shares tips and tricks for a better home and garden at Hunker.com.