A car battery charger provides the power for anodizing.
Home anodizing is an excellent way to make aluminum parts harder and less likely to corrode. The anodizing process uses electricity to create an aluminum oxide coating. You can even add a touch of color. Many common aluminum products are anodized, from bicycle parts to cookware, but some require a custom process. Home anodizing is popular for auto and bike parts, paintball markers, telescopes and many other aluminum items. It’s safe and relatively simple to do, as long as you take a few precautions.
1. Clean all aluminum parts in a solution of nitric acid or lye. Combine 1 to 2 oz. of nitric acid with each gallon of water, or 3 tbsp. of lye with each gallon. Remember to add lye or acid to water, never the other way around. Adding water to lye or acid can cause a hazardous reaction. Place the aluminum parts to be anodized in the solution. The lye or acid should eat away oil and other contaminants that can interfere with the anodizing process.
2. Create the electrolyte–the solution through which the electricity will travel. An electrolyte is a substance that conducts electricity more effectively than just water. Mix one part battery acid with three parts water in a nonreactive container large enough to hold the aluminum part and the cathode.
3. Place the parts. Suspend an aluminum part in the electrolyte. Choose another aluminum object, such as a piece of scrap, to be the cathode–the negatively charged electrode. Suspend it in the electrolyte, but do not allow it to directly touch the part to be anodized.
4. Attach your power source. Clip the negative lead of your battery charger to the cathode and the positive lead to the aluminum part.
5. Turn on the power. Set the battery charger to a rate of 2 volts or more. Choose a higher voltage for faster anodizing. The cathode will produce a white fog or a stream of bubbles if power is flowing through the tank correctly.
6. Leave the parts in the electrolyte with power flowing until the surface of the aluminum part appears yellowish and dull. You may see fewer bubbles or a change in the flow of the bubbles. For small parts, this process takes about two hours. Larger parts may require more time or more current.
7. Turn off the power and remove the aluminum part from the electrolyte. Rinse thoroughly with distilled water.
8. Mix distilled water and fabric dye in a nonreactive pot. A higher concentration of dye will yield a darker color. Place the part in the dye solution at room temperature, then heat the mixture to 100 degrees Fahrenheit for about 15 minutes. Remove the aluminum part from the dye solution. Rinse thoroughly with distilled water, but do not scrub.
9. Fill another nonreactive pot that’s large enough to hold the aluminum part with distilled water and bring it to a boil. Place the part in the boiling water and leave it there for a half-hour to harden the finish.
10. Remove the part and allow it to dry. Cool the part to room temperature before using.