Question

what is anodising?......​

Answer 1

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The layer of aluminium oxide on the surface of aluminium objects can be made thicker by electrolysis ( to give them even more protection from corrosion). This process is called anodising.

Answer 2

Anodising is an electrolytic process for producing thick oxide coatings, usually on aluminium and its alloys. The oxide layer is typically 5 to 30µm in thickness and is used to give improved surface resistance to wear and corrosion, or as a decorative layer.