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Anodizing process colours

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  • The Creation of Colour

    This is the first process that Covit does on the "Baby Line" in the laboratory. Customers send a colour sample or provide a reference or Pantone value and the colour is matched to it for approval. Of course, even under varying conditions, Covit must be able to reproduce the same colour throughout production, agreeing upon acceptance limits.

    The time needed to develop a colour depends on the number of dyes needed. Complexity increases as more colours are added to achieve the correct colour.

  • DYE

  • The dye itself

    The dyes are purchased. Covit works with the only two suppliers in Europe who are able to meet the specific needs of the market.
    The prices of the colours can be ordered from smallest to largest, from 1 to 3. Reds and purples are usually the most expensive.

  • The Dye: in production

    For the production of each colour, the anodizing line features a container called the "colour bowl". In these containers the colours of the baths are prepared. The dye is the main component of each bath. To fill the capacity of the tanks, a certain amount of chemicals are needed (including dye).

    The ratio between the dye and other chemicals determines the outcome. This is called "concentration". In general, for dark colours, the concentration in the bath is high and therefore more expensive.
    The concentration does not remain constant throughout the process. Maintaining the colour of the bath has to be done with a certain frequency, at least once or twice a day. Maintenance entails restoring the original aspect ratio. To control the stability of the proportion, Covit uses spectrophotometers. The maintenance of darker colours, with a high concentration of dye, is obviously more expensive.


  • The Process: Anodizing

    The key process in anodizing is oxidation. In a specific bath a porous layer of aluminium oxide is created on the surface of the pieces. This layer can have different thicknesses.
    The cost of the oxidation process depends on the colour intensity. Light colours, with a low concentration of dye, are less expensive than dark colours with a high concentration of dye. Light colours require a thinner layer of aluminium oxide than darker colours.
    The combination of several parameters (time, temperature, power consumption and electrolyte concentration) determines the thickness of the layer and hence the cost of preparing and maintaining the oxidation bath.
    Processes that require special preparation costs and extraordinary controls are referred to as “Special Oxidation”.


    Covit boasts a very high anodizing capacity. The Covit line features 18 colour baths, meaning pieces can be anodized simultaneously in 18 different colours.
    The colours produced by the process of special oxidation need more frequent and thorough checks by technical personnel.
    The more complex colours, consisting of two or more dyes, also require more frequent monitoring and care. Black is also included in this group because it is very sensitive.

  • Examples