The bassoon is an instrument that requires many pieces to be put together before it can be played. There are joints between the pieces, which help connect them together. These joints can be made of either cork or string. The cork joints require application of cork grease, as the name implies.

On the Other: Threaded Joints

Bassoons that are made with threaded (or string) joints do not require cork grease. In fact, applying cork grease to threaded joints can damage or ruin the instrument, requiring parts to be replaced. Some bassoon specialists, like James Laslie, say that using cork grease on threaded joints is acceptable only if instrument owners "start out with it in the beginning," but it is generally cautioned against.

Bottom Line

Most bassoons are made with cork joints, and for owners of such an instrument, it is important to apply cork grease to the bassoon before putting it together and playing. According to Yamaha, a well-known maker of musical instruments, it is also advised to apply cork grease to the cork joints again after playing, prior to putting the instrument away. It is only when a bassoon has threaded joints that the owner must avoid using cork grease lest it damages the instrument.

Source:

Yamaha: Caring for Oboes and Bassoons

International Double Reed Society: James Laslie-Bassoon Specialist