Valve oil

(The brass on the outside of a modern instrument is lacquered or plated to prevent corrosion.)

Even a minor binding of a valve affects the play-ability of the instrument and is at least very annoying.

However, woodwinds usually oil their keys only every few months, whereas some brass players lubricate their valves several times a week.

Accordingly, vendors sell different types of oil, including scented varieties.

Their characteristics include, but are not necessarily limited to, greater compatibility with other related oils without chemical reactions (some types of mineral based oils or their additives were known to react with each other, forming thick solids - this required disassembly and complete cleaning of the valves to restore operation), slow evaporation or total lack of evaporation resulting in fewer oilings required, and less dissipation on contact with moisture inside the valve.