Anodizing is NOT a topic suitable to be covered on a yoyo board… it’s an inherently dangerous process using electricity and strong acid… there is now way in … that I’m going to have kids thinking this is easy/safe or a good idea to do at home.
I will give a brief overview of what happens though.
The metal is stripped of all oil, dirt, grease, fingerprints, everything. Usually a strong ‘degreasing’ compound is used.
The part is immediately put into an an acid bath and electrified. This causes the surface of the aluminum to build an oxide layer. That layer forms tiny microscopic little tubes. At this point the part still looks silver/gray. You are basically making aluminum into a porous surface that can hold dye.
The part goes into a dye bath… this is where the color comes from. The dye isn’t all that dissimilar from RIT dye you’d find at the grocery story, just stronger.
If you are doing a splash, you would do it just like any other splash dye job… you dye a color, mask off an area, dye a darker color, mask off, dye another color, etc.
If you are doing a fade you dye part of the yoyo by only partially submerging it, then you slowly remove it to create a transition area, then do another color the opposite. The longer the part stays in the dye, the darker the color will get, so by removing it slowly you create a fade out effect.
The part is sealed to trap the color in the oxide layer.
You sell the part for some overly inflated price.