Black oxide may be faster and more durable than paint for parts like springs.
The industrial process name is Oxide passivization.
It's similar to Bluing and Parkerizing on firearms. You're using a chemically produced oxide of Iron to provide corrosion protection.
Caswell sells kits that work well.
This guy uses dirty motor oil as a final step. I use clean motor oil.
I've used black oxide on threaded hardware and washers, Zinc plating with Chromium yellowing on carburetor bodies to mimic the original cadmium plating, and electroless copper and nickel on machine tool handwheels.
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1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8
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