Nitric Acid Passivation and Reprocessing Instruments

A crucial part of instrument finishing is the Passivation Process, this is a Nitric Acid surface treatment to remove foreign bodies and oxidise the surface of the material to increase corrosion resistance. Passivation should only be performed by trained technicians, who have suitable protective equipment and knowhow.

The ability of surgical instruments to re-process through sterile services, without any problems i.e. rusting and corrosion, is a very good sign of its quality. This is particularly important, as most instruments are made from Martensitic Steels, and therefore have more chance of corrosion.

A copper sulphate test may be used to check for improper material selection and we may do this, if passivation indicates poor materials. This is also very useful, when we are processing repairs and refurbishing instrument trays, as it aids identification of poor quality steels, which may contaminate whole trays with rust. The test can also be used to check passivation has been carried out correctly, as it identified any free iron, remaining on the surface of the stainless steel, which would be a corrosion risk.