DIN 50938:2025-06

This document specifies requirements and test methods for black oxide coatings produced on ferrous metal components by a chemical reaction during an immersion process. Room-temperature blackening by means of acidic solutions containing heavy metals and other methods of producing black oxide coatings are not covered by this document. Black oxide coating provides iron and steel (namely cast iron, unalloyed and low-alloy steel) components with uniform black coatings to give the material a particular appearance while substantially retaining their dimensional accuracy. This document is not applicable to fasteners and semi-finished products. This document has been prepared by Working Committee NA 062-01-76 AA "Chemische und elektrochemische Überzüge" (“Chemical and electrochemical coatings”) at DIN Standards Committee Materials Testing (NMP).