How To Anodize Aluminum Black. Some aluminum will be deposited at the cathode but it can be removed easily. 4 grams of naoh in 196 ml of tap water.
This is done through a secondary operation with either an organic or inorganic coloring. After hard anodize, the part may be machined, ground, honed, lapped or stripped to remove areas of the coating. Don't let it touch the aluminium part at the anode.
Those spots will not be shown before anodizing;
We are looking to coat the inside of a optical cavity. Make a 2% (dilute) solution of sodium hydroxide (drain cleaner, naoh) if you desire an etched surface prior to anodizing. An agitator (optional) safety gear; You can see it only after anodizing process.