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Metal Finishing Services

What is Passivation?

Passivation is a process that promotes great corrosion resistance in metal parts. Passivation is a process which promotes the build-up of an oxide layer proving protection from corrosion.

What is the Process?

Passivation is a non-electrolytic process which typically will use nitric or citric acid. With components made of stainless steel for example, the passivation process removes the free Iron from the surface, but leaves behind other components of the alloy such as Chromium and often Nickel. These remaining elements react with the oxygen to form the oxide layer which protects the steel from corrosion. In order to be carried out effectively, the part must be clean and quite often parts may need to undergo a Pickling process to remove impurities.

Passivation is quite often used in conjunction with other processes, as an example in Zinc Plating and also in conjunction with Pickling, but we also offer it as a process in its own right. In order to effectively carry out the Passivation Process, the part must be clean and free of any dirt or oils.

Range of Colours

Passivates are available in a range of colours including: Yellow, Black, Oliver Drab and Clear. Although it would be unusual to use a process like Passivation for decorative reasons, certainly by using a specific colour for your parts it will make them easier to identify. Trivalent Passivation has an iridescent blue colour. 

Specifications Offered:

ASTM A380, ASTM A967, AMS 2700, AMS-QQ-P-35, ASTM F86M, ASTM B600, BS EN 2516, MIL-STD-808A

What Silchrome Offer:

Silchrome can a full Passivation service for parts which may include pre-treatment through Pickling. We currently offer Passivation which uses both Hexavalent and Trivalent Chrome, but anticipate due to environmental restrictions, we may only be able to offer Trivalent based Passivation in the future.

Silchrome offer a wide range of colours including: Clear, Yellow, Olive Drab and Black.

All of our processes are carried in house at our production facility in Leeds and Silchrome Plating are IS0 9001 AND ISO 14001 approved. 


  • The official logo for the Surface Engineering Association.
  • The official logos for the ISOQAR and UKAS industry regulatory bodies.
  • The official logo for the Institute of Materials Finishing.
  • The official logos for the ISOQAR and UKAS industry regulatory bodies.