Our range of finishes include

  • Alocrom 1000 & 1200 (for Aluminium)
  • Iridite NCP (for Aluminium)
  • Chrome III Thick Film Trivalent Passivation
  • Hydrogen De-Embrittlement
  • Lacquering
  • Rogard Supreme Seal 500
  • Zinc Electroplating (Clear, Yellow & Olive Passivation)

Aluminium Conversion Coating

(Incorporating Alocrom 1000, 1200 and non-chromate Iridite NCP)

The Process


The component will firstly be thoroughly cleaned, degreased and mildly etched prior to this process commencing.

The treatment chosen is then applied by either brush or swab to localised areas or by immersion if required for the entire component. Once applied or immersed the process will take up to 5 mins to create a thin, clear or gold coloured, protective film across the component or area treated.

The component is then rinsed initially in cold clean running water for 30 seconds, followed by a hot rinse across within a weakened treatment solution for 15-30 seconds.

The technician will then make a final inspection to make sure the component or area treated has an even clear or gold coloured coating.

Please note


For customers that require a non-chromate conversion coating to satisfy the requirements of the RoHS and WEEE directives, we offer Iridite NCP which produces a clear surface coating with corrosion resistance of up to 1000 salt spray hours using ASTM B117. Iridite NCP is also temperature resistant making it suitable for high temperature operating environments such as automotive engine components and electronic heat sinks, as well as offering excellent adhesion to paints, sealants and adhesives.

Some industries are still unclear if the Alocrom process conforms fully to the legislation as some Alocrom treatments may contain Hexavalent Chromium. However, the manufacturer states that the resultant items meet the RoHS and W.E.E.E. directives.

The following extract from their Guidance Note [P/WRGN-1/1, December 2004] explains this in more detail:


Alocrom 1200 (Gold) and Alocrom 1000 (Clear) coatings have reaction mechanisms that utilise Hexavalent Chromium but the resultant items meet the Directives for the following reasons.

  1. The electrical conductivity of the conversions requires coating weights from about 40 to 300 mg/m2. with the hexavalent chromium component making up not more than 15% (IMDS data base reference 78342/3). The remainder of the conversion comprises trivalent chromium, aluminium, oxygen etc.


  2. For such conversions to be effective they must be fully integrated with the metal surface and so cannot be readily removed by either physical or chemical means except by using highly aggressive techniques, which will also remove the underlying substrate. Metal removal rates would need to be less than 17µ (significantly less than 1 thousandth of an inch) before the limit of 0.1% w/w might be exceeded - for the clear conversion, this figure would be much less.


  3. Sensitive tests on a random 12 examples of golden chromate conversion from actual production lines, using the classic spot test for hexavalent chromium, showed negative results in every case. The reduction of the hexavalent chromium, when the surface has been fully dried, Is such that none effectively remains.

In addition to the above, it must be appreciated that a large proportion of commerclal alloys contain significant amounts of both Cadmium (in Zinc) and Chromium (in Steels and Aluminium alloys). Extraction processes for analysis often easily digest these contaminants.
Further information can be obtained, if required, from Trimite Limited.