The colour of oxid layer on aluminium depends onkind of primary input.
The factors are the kind and the percentage of alloy components in primary imput and also the conditions of metal acquirement. The rule is the most homogenic coatings are attained on materials, which were mechanically deformed or were subjects to temperature homogenization. Totally colourless coatings can be get only in case of anodization of pure aluminium in solutions of sulphuric acid and moderate electric density. The use of high-alloyed material results in gray coatings and in case of high percentage of silicon - even black. Improper homogenization of alloys spurs occurrence of stains of various colour.
THE THICKNESS OF A COATING
The thickness of oxid coatings on aluminium depends on given conditions of anodization and also on the composition and structure of primary input. For low-alloy materials and those mede of pure aluminium we produce coatings of tickness ranging from 5 - 25 µm depending on Client's requirements. For products made from alloys of 7xxx series - to 20 µm and for alloys of 2xxx series - to15 µm.
In chart 1 we showed required thickness of coating depending on supposesed application.
HARDNESS OF COATING
The hardness of coating depends to a great extent on parameters of anodic process. The hardness of conventional coatings is of 100 to 300 kg/mm2 in Vickers scale and it diminishes as coating becomes thinner.
COATINGS' PRONENESS TO COLORING
The rule is that the easiest to colour are coatings made on pure aluminium (1xxx) or low-alloy materials (3xxx, 5xxx, 6xxx). Poor susceptibility to coloring is among alloys of high-copper (2xxx) and zinc (7xxx) and cast alloys with high silicon percentage (more than 3%).
CORROSIVE RESISTANCE
Corrosive resistance of oxid coatings depends on thickness of anodic coating, the quality of its tightness and also greatly upon the kind of used aluminium. And so the best corrosive resistance present coatings made of pure aluminium (1xxx) and low-alloy material (especially 5xxx). Far inferior anti-corrosive properties show high-copper (2xxx) and zinc (7xxx) coatings. Aiming at streamlining the choice of a kind of aluminium proper for You in chart 2 we present applicability of aluminium alloys to a given type of chemical and electrochemical treatement.
kind of primary input.
The factors are the kind and the percentage of alloy components in primary imput and also the conditions of metal acquirement. The rule is the most homogenic coatings are attained on materials, which were mechanically deformed or were subjects to temperature homogenization. Totally colourless coatings can be get only in case of anodization of pure aluminium in solutions of sulphuric acid and moderate electric density. The use of high-alloyed material results in gray coatings and in case of high percentage of silicon - even black. Improper homogenization of alloys spurs occurrence of stains of various colour. 
HARDNESS OF COATING 
CORROSIVE RESISTANCE