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Annodizing

Electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts

Steps

  1. Clean the aluminum
    • Use soap and water,
    • or a degreaser (if oil remains)
    • or a solvent such as acetone to clean the surface.
  2. Prepare the anodizing solution
    • Mix a solution of sulfuric acid and water
    • The concentration of the sulfuric acid == thickness of the anodized layer
      • A common ratio is 1 part sulfuric acid to 3 parts water
    • Be sure to add the acid to the water
  3. Set up the anodizing bath:
    • The anodizing bath should be set up in a plastic or glass container
      • acid can corrode metal containers.
    • Suspended part in the bath using a hanger or wire.
  4. Connect the power supply
    • Connect the positive lead of the power supply to the aluminum part
    • The negative lead to a piece of aluminum foil or another conductive material in the bath.
  5. Anodize the aluminum
    • The longer the part is left in the bath, the thicker the anodized layer will be.
    • Typically, anodizing times range from 30 minutes to 2 hours.
  6. Rinse the part
    • Rinse it thoroughly with water
    • Be sure to wear gloves and eye protection during this step.
  7. Color Part If Desired
    • While the anodizing process is going on, heat your dyes.
    • For most colors, 140° F works best for most colors
      • but some work better at cooler temperatures.
    • You’ll have to experiment with your brands and colors.
    • Prepare one tank of distilled water and another with your acid neutralizer
  8. Seal the anodized layer
    • Boiling the part in water
    • or using a commercial sealer
  9. improve the corrosion resistance
  10. Dry the part