The Bernzomatic Company was founded by Otto Bernz in 1876 and has been manufacturing torches to the present day. Over the years, Bernzomatic has developed and refined torches to the point where, as of 2010, specialized torches are available that use different gases. One such torch is the Model ST250K butane-powered microtorch, which includes soldering iron tips. Knowing how to use a soldering iron correctly is the key to success in your soldering projects.
Use the Correct Tip
Sizing up the tip to the job is all-important. Three soldering iron tips are available in the ST250K microtorch kit: chisel point, large cone and fine rod–shaped. Use the chisel point for larger areas to be soldered, and use the large cone for large spot-soldering. Use the small pencil tip for fine, delicate soldering work, such as soldering components onto printed circuit boards.
Know the Limitations of the Tool
This microtorch is designed for small, very precise soldering jobs. It is not designed for soldering heavy plate steel or large plumbing applications. Trying to exceed the capabilities of the torch will result in a bad solder joint, since heavy items will draw heat away faster than the melting temperature of the solder. If you have to do a large soldering job, use a bigger soldering torch.
Heat the Base Metal First
This is the golden rule of soldering. Do not melt the solder with the tip. Rather, heat the metal you are soldering, and touch the solder to the metal so that the metal melts the solder. This results in a good solder joint. A good joint looks mirror shiny and has a very smooth surface. Not letting the base metal melt the solder will result in a "cold" solder joint, which looks dull and has a crinkled surface. A cold joint will not conduct electricity and is structurally unsound.
Tin Your Tip
Allow your iron to reach operating temperature. Have a damp sponge or rag handy. Melt a generous amount of rosin-core solder on the tip. Quickly wipe off the tip with the damp sponge. Be careful, since the excess solder can spatter. This removes all oxidation from the tip and allows for good heat conduction between the tip and the base metal. As you are soldering, when the tip becomes oxidized (dull brown spotting), repeat the process. Never use acid-core solder on electrical work, since the acid will corrode the metals. Acid-core solder should only be used on plumbing work.
Practice, Practice, Practice
Soldering is an art that developed into a science. You have to practice on scrap pieces of metal first to develop the right "feel." Too little solder, and the soldered joint will not be structurally sound, Too much solder, and the joint will become a cold joint. Timing of heat application and how much solder to use are huge variables, and you have to develop techniques to refine your skills.