Explanations: Aircraft Finishes Flashcards
What is retarder?
a special type of thinner that dries slowly. It is used in dope and lacquer to slow its drying time. The slower drying time prevents blushing and provides a smoother finish.
What is wash primer?
a two-part primer that contains phosphoric acid to etch the surface of the metal to improve the bond between the surface and the topcoats.
What is polyurathane noted for?
Its chemical resistance and for its famous “wet look” that is caused by its slow flow-out time.
Describe aluminum-pigmented dope.
contains tiny flakes of aluminum metal that spread out to form a solid, lightproof film over the coats of clear dope.
What is acetone?
a fast-evaporating dope solvent that is suitable for removing grease from fabric prior to doping.
It is also used for cleaning paint spray guns and as an ingredient in paint and varnish removers.
What must you first do before dry sanding a fabric covered surface?
Be sure to electrically ground it to a cold water pipe or some other good electrical ground.
The process of sanding may create a spark that ignites the highly flammable fumes inside the structure.
Why can unhydrated wash primer create corrosion when applied to an unpainted aluminum surface?
Wash primer requires moisture to convert the phosphoric acid into a protective film on the surface of the metal. If unhydrated wash primer, primer without enough water to effect the cure, is applied, and within 30 to 40 minutes it is covered with a dense film of a finish such as polyurethane, there is a good chance that filiform corrosion will form under the coat.
What is blushing?
a condition in dope or lacquer finishes in which moisture from the atmosphere condenses on the surface and causes some of the cellulose to precipitate from the finish.
Blushing leaves a porous, dull, and weak finish.
What causes blushing?
it may be caused by the temperature being too low, the humidity being too high, by drafts, or sudden changes in temperature.
Old wash primer coats may be overcoated directly with epoxy finishes, under what necessary condition?
that a second coat of wash primer be applied to the surface if an acrylic finish is to be applied.
