[cprocess]

I agree with the recent reply of a solution of sodium hydroxide and water. However, this solution will also etch the aluminum, leaving a matte finish. Sodium Hydroxide can also aggressively attack aluminum if the concentration and/or the temperature is too high and the part is immersed too long. If the sodium hydroxide solution is your only choice, you should immerse the part for about 1 minute. If the part begins gassing excessively, remove and rinse immediately. You should use proper ventilation, since the reaction of sodium hydroxide with aluminum gives off hydrogen gas, which is explosive (remember the Hindenburg?)
If you want to strip the anodized coating and leave the surface of the aluminum unetched, you can use a solution of 3.5%/vol Phosphoric Acid + 2% by weight chromium trioxide + water to final volume. Since chromium trioxide forms chromic acid (hexavalent chrome) when mixed with water, you may want to contact a metal finishing facility to do this strip work for you.
Additionally, Nitric acid will not strip most anodized coatings.
Hope this information helps!
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