Wash
Wash turns up in 2 fields: powder coating, lighting. Here is what it means to the people in each one.
Wash in powder coating
Line slang for the spray pretreatment washer, or for the pass a part makes through it.
On the floor, the whole multi-stage pretreatment system is simply the wash, and a part either went through the wash or got hand-wiped. Problems are blamed on the wash when water spots, flash rust or poor adhesion show up. The word covers everything from the cleaner tank to the dry-off oven exit.
"Run those back through the wash, they came out of the dry-off with water spots all over."
Wash in lighting
Broad, even light covering a whole stage area or surface, built from overlapping soft-edged fixtures.
A system of fixtures aimed and overlapped so that a performance area or surface is lit evenly in one color or direction, such as a front wash, a blue back wash or a cyc wash. Designers usually build several washes and combine them in cues. Fresnels, LED wash fixtures and softened ellipsoidals are typical tools, and smooth blending without dark gaps between areas is the measure of a good one.
"Front wash has a dark hole at center stage between areas 5 and 6, spread both units another couple of feet."