The process of soldering is actually nothing more than gluing two pieces of metal together, with the solder being the glue. Because brass is a metal that offers both beauty and durability, it has many uses. Brass contains both copper and zinc and has a high melting point between 900 and 940 degrees Fahrenheit. When you use a simple solder, such as one containing 60 percent tin and 40 percent lead, with a melting point of only 365 degrees Fahrenheit, you won't have to worry about melting the brass. Some lead-free solders have even lower melting points.
In order to get two pieces of brass to hold together, it is first necessary to clean both pieces thoroughly. To clean the brass, you will need to use a very fine grit emery cloth to polish both of the sides that will be joined together. Sand both parts and wipe away any grit and dust with a damp, soft cloth to help the parts stick together and provide a strong joint.
Next, use soldering flux, which not only cleans brass parts, but will also help the solder to flow into position. Use a small solder brush or cotton swab to brush solder onto both pieces that are to be joined. A light coating of flux will be enough; too much flux might burn and leave a hard-to-clean residue on the joint.
Cut a piece of wire solder and hold the tip next to the joint, and then heat it with a propane torch. As soon as the solder begins to melt, remove the heat source and allow the solder to flow into place. The solder will flow to all areas that were coated with flux. Remove the solder wire as soon as you can see that the joint has sealed.
Removing Excess Solder
If there are any clusters or solder drips on the brass, use solder wick to absorb them. Heat the excess solder until it is just starting to melt and then place a piece of solder wick over it, and the wick will absorb the unwanted run.
Finish the Job
Complete your soldering job by using brown jeweler's rouge on a soft buffing wheel and buff off any remaining unwanted solder and burned areas. Buff the joint a second time using white jeweler's rouge. Areas that cannot be reached with the buffing wheel can be buffed with jeweler's rouge on a soft cloth. To keep the area from tarnishing, spray lightly with clear lacquer.