Metal can be dyed colors after anodizing it.
Metal can have more color than simple silver or gold. Anodizing aluminum allows that metal to be dyed, giving car parts, paintball equipment, and other items a brightly colored appearance. The dye is translucent and the aluminum’s shine can be seen through it regardless of what color you choose. Splash anodizing takes the dye job a step further. Designs and patches in the item can be made by masking areas off before dying. You can even dye them more than once, creating customized designs for visible metal pieces.
1. Clean the aluminum piece with soap and water to remove dirt and dust. Use a solvent cleaner such as mineral spirits, lacquer thinner, or kerosene to remove grease and oil. Rinse the item well in hot water to remove solvent residue. Clean the item in a solution of chromic and phosphoric acids and water, if it has developed an oxide coating through previous anodizing. The acid cleaning will also remove any black film or corrosion, called smut. Rinse the item well, then buff it to the finish you want.
2. Set up the anodizing tank. You will need a power source, a cathode, an anode, and a metal or plastic tank. The power source is a manual battery charger or DC power supply capable of at least 12 volts and 6 amps of power. The cathode is a lead piece larger than the item being anodized. The anode is a piece of aluminum wire that touches the item. The tank can be a plastic container like a picnic cooler or a metal tank, but must be large enough to fit the cathode and the items to be anodized. You will also need a temperature gauge in the tank, and a cooling unit such as an air conditioner outside of it.
3. Fill the tank with a sulfuric acid solution, which consists of 15% pure sulfuric acid and 85% water. Battery acid in a 50/50 mix with water works as well. Connect the cathode to the negative charge of the power source and place it in the solution. Only the cathode should be in the anodizing bath; the connecting electrical wire must be completely outside it. Connect the anode to the positive charge on the power source, and secure the item to the anode. The item will not anodize or take dye where the anode wire touches it, so fasten it into an existing hole or an inconspicuous place.
4. Anodize the aluminum. Rig the item so it stays submerged and suspended in the tank without touching the tank or the cathode. Turn on the power source. Anodizing takes between 30 and 75 minutes. Low power, cold temperatures, or multiple items will take more time. Monitor the temperature and turn on the cooling unit if necessary. The temperature of the acid must remain between 65 and 75 degrees Fahrenheit. Rinse the item well in cold water.
5. Mask a design on the aluminum item. Masking is the process of blocking areas of the object so they do not take the dye. When the mask is removed, these areas will show the silver color of aluminum, and everything else will be the color of the dye. You can use lacquer, asphaltum, photo resists, special tapes for anodizing, or rubber cement to mask areas.
6. Mix a solution of water and anodizing dye in another tank. Anodizing dye is acid-based, and may be called electroplating dye. Heat the dye solution to 140 degrees Fahrenheit. Hang the item in the dye. Fifteen minutes will give it the richest color the dye can produce; for a lighter color, remove the item earlier. Masking can be removed with lacquer thinner or acetone, depending on what you use for a mask. Changing the masking and repeating this step with a solution using a different color of anodizing dye will create a multi-colored design on your metal.
7. Steam or boil the aluminum piece. The heat seals the dye on so it will not bleed away. Steam the item for 30 minutes, or boil it in plain water for 20. You can also use a Nickel Acetate sealer. Only seal the item after you are happy with the color; the piece will not take any dye after it has been sealed.