Definition
An aromatic hydrocarbon solvent (C8H10) used in aviation as a thinner and cleaning agent for dope, lacquers, paints, and certain adhesives applied to aircraft surfaces. It is also used as an additive to raise the octane rating of aviation gasoline.
Plain English
A strong, fast-evaporating liquid solvent used to thin paints and dopes, clean surfaces during finishing work, and boost the octane of aviation fuel.
Context Anchor
Seen in aircraft maintenance, paint and coating work, adhesive removal, cleaning procedures, and safety data sheets for shop chemicals.
Derivation
From the Greek 'xylon' meaning 'wood,' because xylene was first obtained by distilling wood. Knowing this hints at its origin as a distilled, oily liquid -- the same family of solvents used to thin wood and metal finishes.
Why Pilots Care
Xylene is flammable and its vapors are harmful to breathe, so any pilot, owner, or mechanic using it for touch-up work or fabric repair must handle it in a ventilated area away from ignition sources.
Intuition Check
Do not think of xylene as a normal aircraft fluid like fuel, oil, or hydraulic fluid. It is a shop chemical used for certain cleaning, thinning, or dissolving tasks.
Example Sentence 1
The mechanic used xylene to thin the dope before brushing it onto the fabric patch.
Example Sentence 2
Xylene thinned the paint so it would flow smoothly when lettering the aircraft's registration.