How a Trombone is Made
How the bell is made

High quality bells start with the same process, whether for trombones, saxophones, or trumpets. For 1-piece bells (made using the traditional method of forming the bell from a single sheet of metal), the ends are sintered together, heated, washed in acid, then hammered into shape with a wooden mallet.
A cored bar that has been specially prepared for each model is used to shape the bell. This is by no means an easy task and requires the advanced skills of a craftsperson.

There are two types of materials typically used to make bells. One is yellow brass, which is similar in color to a Japanese five-yen coin, and the other is gold brass, which is closer to the color of a Japanese ten-yen coin. Although both materials are brass, their compositions are different. Gold brass is 85% copper and 15% zinc, while yellow brass is 70% copper and 30% zinc. They also sound different. Yellow brass has a bright and forceful timbre, while gold brass has a shiny and gentle timbre. Players generally choose a material based on whichever sound they prefer.