Chromate conversion process

This process offers a cost effective, non electrolytic method for coating aluminium. The end result forms a good pre-paint finish, corrosion resistance and adhesion qualities. The thickness of the coating is approximately 2um.

- Abacus finishers offers two chromate conversion processes; Alcrom 1000 and Alocrom 1200.

Alocrom 1000

- A chemical which produces a colourless protective coating, without significantly changing the surface. Paint adhesion to this coating is good, however it offers lower electrical resistance than Alocrom 1200. Please see summary table bellow for Alocrom 1000 properties.

Alocrom 1200

A chemical which forms a golden protective chromate coating which offers excellent electrical conductivity and corrosion resistance. This coating is ideal for all types of aluminium alloys, including high silicon pressure die-casting. It is recommended to be used on aluminium wherever maximum corrosion resistance and electrical conductivity are required. Please see summary table bellow for Alocrom 1200 properties

A summary table of the chromate conversion processes available at Abacus Finishers.


Colour Clear Gold
Conductivity +++ ++
Corrosion + ++
Lenght 1m x 1m 1 xm 1m x 1m 1 xm
Width 1m x 1m 1 xm 1m x 1m 1 xm
Depth 1m x 1m 1 xm 1m x 1m 1 xm

Defstan 03-18
Clear MIL-C_5541 Class 3

Defstan 03-18
MIL-C_5541 Class 1

Non chromate conversion coatings - Iridite NCP

- A state of the art new process which offers a high level of resistance to corrosion. The process has been tested up to 1000 hours on many alluminium alloys. It produces a clear surface coating which has high temperate resistance, as well as excellent adhesion to paints, sealants and adhesives.

Sulphuric acid anodising

- Sulphuric acid anodising is the most commonly used protective treatment for aluminium. The process forms a clear silver coloured coating , which can be subsequently dyed the desire colour.

- The process involves the oxidation of the aluminium surface. This forms a thin layer of aluminium oxide under controlled chemical conditions. This process also occurs naturally, however at much slower rate. Please note the process will not hide any surface imperfections on the aluminium substrate. It should be taken into account that the nature of the process will generally degrade the surface finish of the aluminum which should be considered when deciding the qualify of the surface material to be treated.

Being an elecrolityc process, an electrical contact point is required at all times during the treatment, therefore a very small set of jig marks will always appear after treatment.

This anodising process provides a coating of between 5-25 um whereby a thicker coating giving a greater corrosion resistance. Where colour dyeing is required a surface coating of 15-25um is recommended.

We mainly work to two specific standards;

DEF STAN 03-25 (formely DEF 151 TYpe1) BS 1615

Colour options available upon request.