Why hard aluminum surface coatings are not always as consistent as we wish it would be!

What we all want is to get consistent results on our hard anodized parts every time we receive them from the surface finisher, so why do we sometimes get variations in the properties, such as corrosion resistance, hardness, color, thickness, wear resistance, a softer layer or even burned parts, which are totally useless?

There are several reasons for this and a lot of the times it is dependent on the alloy. If the parts are made of different alloys we will get different finishing results.

To get a better idea of what´s going wrong we need to explain how the hard anodized layer is formed.