In burnishing or black oxidation, a thin, strongly adhering black oxide layer is created on the surface of low-alloy steels by means of an alkaline dipping process. The thickness of this iron oxide layer is approximately 1 µm which offers mild corrosion protection that is, for example, sufficient to protect the interior or against manual welding. This protection can be enhanced by adding oil or grease. Surfaces created by means of burnishing have a greater abrasion resistance and form a good adhesive surface for subsequent coatings.



Burnishing is used on machine parts, tools, furniture fittings or weapons. The decorative black appearance of the conversion layer makes it particularly attractive for visible parts.

G.W.P. offers the high-quality burnishing of steel in accordance with DIN 50938:


  • Low-alloy structural and tempering steel (such as C45, C60, 42CrMo4)
  • Decorative black surface
  • Layer thickness of approximately 1 µm
  • Sufficient corrosion protection
  • Enhanced abrasion resistance
  • Temperature resistant up to approximately 300°C
  • Good adhesive surface