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Deleted member 174758
Good quality screwdrivers are normally polished and chromium plated (for rust resistance). Shot blasting (they don't actually use sand) of the tips removes this plating and the tips are then chemically blacked so that the unchromed parts can be clearly seen. AFAIK this originated in the 1970s in products made for the aerospace industry where chromium chips from screwdriver tips can result in bearing failure or blocked jets - potentially catastrophic in a jet engine for exampleSometimes the tips are sandblasted to take the shine off (may look black) though a driver that fits correctly should not slip, even if polished. Especially PZ.
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