Working on getting these trucks & rocket cleaned up and ready to get anodized!
The anodizing process requires the aluminum to be completely rid of any oils or stains so that the ink can properly cling to the material. From what I understand, the metal actually absorbs the ink into itself, sort of like a sponge, but for this to work, it has to be in a chemical bath that charges the aluminum to want to suck things in. If you have any grit or grime on the part's surface, the ink can't enter through it and leave splotchy patches; this is why you have to thoroughly clean each part before anodizing it.
Some processes even go so far as to let it soak in an acid bath to eat away any oils, though it's not entirely necessary if you can clean the part properly.
The plates and trucks come right off the machines with a lot of coolant, so I need to swish them around in hot soapy water to remove the coolant, then rinse each part to make sure there isn't any soap residue leftover. Though we don't really need to do this as they get washed before getting anodized, it makes the later job much easier and ensures we have a better finish.