[Tatu Salmela]

Untreated aluminium tends to oxidise with spit, creating a white foam which is not healthy. Motorcycle shops and hobbyists are helpful with anodising, it needs some equipment and good ventilation. You can do some small-scale anodising in a well-ventilated workshop or garage, but you need a large container of non-reactive material which can stand heat (glass or ceramic perhaps), and I haven’t found a 50 cm tall glass jar yet.