Tips On Soldering Trumpets and Other Musical Instruments

By: JL Bowers, The Bandroom

Soldering is defined as the joining of metals by a fusion of alloys which have relatively low melting points. Soldering is tricky and intimidating, but easy to understand in theory. It takes many hours of practice before a skilled technician can acquire factory results.

Soldering is similar to gluing with molten metal. solders are usually 60% tin and 40% lead. Large brass bows are made stronger by using 50% tin and 50% lead. Solder is commonly mixed with flux, which helps the solder become more pure. Flux is actually an acid or a combination of two or more acids, perhaps diluted with water. Sometimes, flux is part of the alloy of the soldering wire, in an easy to use mixture the flux is in a semi-solid form inside the core of the flux wire. If you are going to use a liquid flux, it is a good idea to have a Hypodermic Needle Dispenser to apply the solder in a precise manner.

I will attempt to walk you through the delicate procedure of soldering musical instruments. In the following instructions, we will assume that we are using a 60% tin 40% lead solder and a liquid flux in a Hypodermic Needle dispenser. I will be explaining how to resolder a broken trumpet brace that attaches the leadpipe Near the receiver to the bell crook. My reasoning for choosing this particular brace is because this is the one brace that breaks when people attempt to remove a stuck trumpet mouthpiece without proper experience, tools or instruction.

 First, be sure to wear safety glasses and a charcoal breathing apparatus. Be sure the room/area you will be soldering in is well ventilated and there is a fresh air source.

 SOLDERING CAUSES VAPORS THAT CAN KILL YOU!

You will need to obtain a portable torch, or have access to a small acetylene torch. You will also need to use a pencil flame tip. A standard propane plumbers torch or cutting torch will burn far too much laquer from your horn, and the end result may be an extremely damaged instrument or even worse, a completely destroyed instrument.

  The first step in the actual soldering process is cleaning  both the surfaces (The brace feet and the area along the crook and receiver). If your soldering surfaces are not clean, the solder will simply not stick. Don't go crazy, but initially use your pencil flame and heat up excess solder using a touch-and-remove heating process until you see the solder is soft and gently wipe it away with a piece of tissue paper, not a paper towel. Toilet or other tissues usually have far less chemicals in them, than paper towels.

Once you have the excess removed, use some ragging strips with some medium grade buffing compound on them (tripoli or chrome compound). See-Saw the ragging strips across the crook surface area and the bell surface area lightly until the excess sodler is gone. Take care not to buff to big an area or your end result will be an eyesore. Heat the braceing feet with the torch and wipe away the excess solder from them as well. Finally, use a clean cloth with some cold cleaner or mineral spirits on it to clean off the buffing compound. Wipe the area with a clean piece of tissue paper to test the area for remaining compound.

Next, scuff the area to be soldered with some extra-fine grit sandpaper followed by "000" steel wool. Take two small pieces of steel wire Not copper or brass and wrap one piece around the foot on the bell side and around the bell itself. Twist the wire gently until the foot is relatively secure. Do the same thing to the opposing receiver side. Now you have your brace set where you need it to be and it is time to solder.

We will solder one side at a time, taking our time and using the least amount of heat possible to get the job done. Remember, heat travels and the further it travels the more laquer you are likely to burn. Start by heating the foot up for a few seconds. Once you feel it is fairly hot, apply two drops of flux in between the crack at the top of the joint. Step back and dont breathe the fumes. The flux will prepare the surface for soldering. Make sure you dont apply more than a few drops of flux. Otherwise the flux will run onto other parts of the horn. Keep in mind, FLUX IS ACID and when you heat it up more, it will BURN OFF THE LAQUER far worse than just heat alone. So use it sparingly.

Next, reheat the foot about twice as long as you did before. Once you get it really hot, simply touch the crack where you applied the flux with a very small piece of your soldering wire. Then quickly release the wire. Add more heat to the side opposite you are feeding the solder because the solder will follow the heat. Repeat this process until the crack all the way around the foot is filled with solder. Quench the work area well and wipe it dry. If you have a small amount of excess, simple heat it a little at a time until you can wipe it away with a tissue. Repeat this process on the opposing side.

Next, remove the securing wire taking care not to scratch the instrument. Use the ragging strips to buff the area you soldered and clean it again with your solvent. Once you have it cleaned, you can use the torch to touch-and -release the soldered area. If you look closely you will see that the brass will darken as you do this. This process will help you to match the brass to the laquer, making the repair less noticeable. Once the areas are completely cooled, spray several very thin coats of aerosol laquer over the area.

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