Definition
An additive used in paint or finishing products to slow the drying or evaporation rate, allowing the coating more time to flow out smoothly before it sets.
Plain English
Something mixed into paint to make it dry slower, so the finish has time to settle evenly instead of drying with streaks or marks.
Context Anchor
Seen in aircraft fabric-covering and finishing work, especially when mixing or applying coatings in conditions where drying time matters.
Derivation
From the Latin retardare, meaning 'to delay or slow down.' In aviation finishing, the additive does exactly that — it delays drying so the paint can level out properly.
Why Pilots Care
A properly applied finish helps protect fabric-covered aircraft surfaces. If coatings dry too fast or are mixed incorrectly, the finish can come out uneven or defective and may need to be corrected before the aircraft is returned to service.
Intuition Check
Do not think of a retarder here as a brake or a control in the aircraft. In this maintenance context, it is a liquid additive that slows the drying of a coating.
Example Sentence 1
On a hot day in the hangar, the painter added a retarder to the topcoat to keep it from drying before it could level out.
Example Sentence 2
They mixed retarder into the enamel before spraying the control surfaces on a warm day.