Average Mark
Retrobike Rider
Righto. Anodising is the process of creating a controlled aluminium oxide film on aluminium. Alu is actually highly reactive and would do this naturally, in fact after cleaning alu we have to "de-ox" it to remove the film. The coating itself is a kind of honeycomb structure extending from the substrate, this is specced to a specific thickness. Usually for hard your looking at 25um, soft around 20 but it is controllable. Rule of thumb is a 50/50 split in this dimension, with 50% being growth and 50% being into the substrate. The oxide film stops the reactive substrate from forming a cell and continuing to corrode. The sealing of the film plays a very important part in the corrosion resistance provided. Nickel Acetate, Hot water and Di-chromate are 3 of the most readily available. You will get a dimensional change in the parts being anodised, but you would need a really bad plated to affect the strength to any noticeable affect.
