How a Tuba is Made
Bringing Out the Shine

Repeated polishing using many different techniques

There are a variety of ways to polish metal into a beautiful shine. Automated approaches are making progress, with the inner and outer surfaces of the bell polished by machine, robotic arms used to file the contours, and automatic polishers used to make large swoops around a tube fixed in place. Buffing is also an important process that has long been performed by very experienced technicians.

A large polishing machine using an array akin to a large set of mops

A large polishing machine using an array akin to a large set of mops

Before polishing, heat treatment is used on the inside of the instrument. Oxidation produces the bronze color.

Before polishing, heat treatment is used on the inside of the instrument. Oxidation produces the bronze color.

A bell that has been polished once (two more rounds await)

A bell that has been polished once (two more rounds await)

Are large instruments as challenging as they look?

Buffing is a process that is also used to polish many other brass instruments such as the trumpet and horn. Especially advanced skill is needed, however, to polish a large tuba and its parts. Since the diameter and hardness of the rotating part, as well as its openings, can vary, several machines are used depending on what is being polished and how much it is being polished.

Using different machines to polish different pieces of the tuba

Using different machines to polish different pieces of the tuba

Polishing the huge bell of the sousaphone

Polishing the huge bell of the sousaphone

Buffing the tuba with walnut shells?

Let's have a look at one more step in the finishing process-polishing the valves. A device called a barrel is filled with fine, brown powder from ground walnut shells. As the barrel slowly rolls, the powder polishes the surface of metal parts rolling around inside. Walnuts are well suited to this because of their oil content. In some cases, plastic powder may also be used.

Placing an instrument into the barrel

Placing an instrument into the barrel

The brown powder inside is the polishing agent

The brown powder inside is the polishing agent

When closed, the barrel is a huge hexagon

When closed, the barrel is a huge hexagon