MIL-DTL-13924 Revision D:1999

This specification covers inorganic black coatings applied to ferrous metals (carbon,
low alloy, and corrosion resistant steels, and wrought iron). Inorganic black conversion coatings,
with or without a supplementary preservative treatment (see 3.11), may be used where a black
surface is required. Only limited corrosion protection, under mildly corrosive conditions, is
obtained as a result of black conversion coating (see 6.1). Black coatings are included in this
specification with limitations as noted in 1.2. Unless contraindicated by contract, chrome-free
finishes should be used in place of finishes containing hexavalent chromium, provided all
performance criteria herein has been met and documented as Objective Quality Evidence (OQE).