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Brightening Process

These stages of the process brightening chemistry: chemical brightening, among the working phases, takes place after the pickling or greasing of the material and before the anodization.
These are the steps followed during the chemical brighning process:

Preparation of material

  • Most of the material that undergoes the treatment of chemical brightening must be pre-treated mechanically, in order to erase the biggest surface imperfections.
    Depending on mechanical processing, the following pre-treatments could be necessary:
    – Glazing chemistry;
    – Alkaline degreasing.

Acid neutralization

  • The material is immersed in a bath of nitric acid to neutralize the basicity of the previous treatments.

Chemical brightening

  • The material is immersed in a tank containing a solution of sulfuric acid, nitric acid and phosphoric acid at about 100° C, the various types of brilliance are a result of the adjustment of the timing of immersion.
  • Entry cab brightening
    Entry cab brightening
  • Immersion in acid
    Immersion in acid


  • An important part in the success of the process is the first rinse after brightening; times transition from the brightening tank to the rinse tank should be minimized to ensure a successful product.
  • Rinse: immersion
    Rinse: immersion
  • Rinse: exit from the tank
    Rinse: exit from the tank


  • The material is dipped into a "decoppering" solution to remove the film of aluminum oxide produced during brightening.
  • Decoppering: immersion
    Decoppering: immersion
  • Decoppering: exit from the tank
    Decoppering: exit from the tan


  • Procedure used to form the thickness of the surface of aluminium oxide by immersion in tanks containing a solution of Sulphuric Acid in 19 - 20 deg. C. The material is connected to the positive (anode) generators current (rectifiers).
    The rectifiers are equipped with APC (Anodizing Process Computer), a device supervision and control of process parameters which (through an automatic calculation of surface to anodize), allows the setting of the number of microns of oxide enough to maintain a constant density of the necessary current.
    During this process the APC controls the value of total output current by indicating on a display the data for processing. At the end of the process, moreover, it automatically prints all the parameters previously monitored.

Colour (possible)

  • Inorganic Colour: based on the principle of precipitation of metal compounds (such as potassium permanganate and Cobalt acetate), dissolved in tanks within the pores the use of aluminium.
    Organic Colour: based on the principle of formation of chemical bonds between various kinds of azo dyes dissolved in tanks, and the layer of the aluminum oxide.


  • It is the final phase of the process, in order to "fix" the layer of anodic oxid by dipping the material in tanks with demineralized water at a temperature of about 100 deg. C with anti-dust products; during this treatment ("hot fixing") the pores of the anodic oxid are closed.


  • After the processing material is dried in an oven (dual position, variable temperature). This makes possible the immediate discharge of material from workstations and the subsequent packaging.
  • Drying treatment
    Drying treatment
  • Drying treatment
    Drying treatment


  • The material, during its brightening process, is continuously washed by immersion in many tanks filled with water, static or running.