Definition
A fast-evaporating, colorless liquid solvent used in aircraft maintenance to clean surfaces, thin certain paints and dopes, and prepare materials for bonding or finishing. It dissolves oils, greases, resins, and many coatings, and is highly flammable with strong vapors that require good ventilation and skin/eye protection.
Plain English
A strong, quick-drying cleaning and thinning liquid used by mechanics to clean parts and prep surfaces before painting or gluing.
Context Anchor
Seen in aircraft maintenance procedures for cleaning parts, preparing surfaces, removing residue, and handling chemical materials in the shop or hangar.
Derivation
The name comes from its chemistry: a 'ketone' is a family of organic chemicals, and this one has a 'methyl' group and an 'ethyl' group attached. Knowing it's a ketone signals it's a powerful organic solvent — useful because that's why mechanics reach for it.
Why Pilots Care
Proper surface cleaning with MEK ensures paint and sealant adhesion, which directly affects structural integrity and corrosion protection.
Grounding Statement
Picture a technician wiping a small aircraft part with a clear liquid that flashes dry quickly but gives off fumes that must not be breathed or exposed to sparks.
Intuition Check
MEK is not just a general cleaner or brand name. It is a specific chemical solvent with serious fire, health, and material-compatibility risks.
Example Sentence 1
The technician wiped the bonding surface with MEK to remove any oil before applying the adhesive.
Example Sentence 2
MEK was used to remove residue from the fuselage joint prior to sealing.