How a Bassoon is Made
Tuning during manufacture

Bassoons have various parts made of metal. These must be plated, but before this is done there is what could be described as a trial assembly, with the metal parts attached to the body of the bassoon, and their locations checked, before the instrument is tuned. After that, the metal parts are polished with a buffing tool and metal plated, and the locations where they come into direct contact with the instrument's body are padded with felt, cork or other materials.

The bottom of the double joint is covered with a protector cap, but this isn't attached with screws or similar fasteners, and instead is just pushed in. If the cap is too loose it may fall out, but conversely if it is too tight it will be impossible to insert fully. If red crayon is applied to the interior of the cap, the crayon gets rubbed onto the double joint at spots where the fit is too tight. This shows where it is necessary to make fine adjustments to the fit, by filing these areas away.