How do you clean aluminum?

Aluminum is a light-weight metal with a bright silvery luster. Small amounts of other metals are added to aluminum to make harder alloys for most uses. Its affinity for oxygen makes it resistant to corrosion and attack by most chemicals. Most aluminum used in visible parts of appliances is lacquered or otherwise coated, anodized or painted.
Aluminum reacts with air to grow its own thin oxide coating very fast. This hard, dark gray coating protects the metal. It's found on all bare aluminum surfaces, including utensils which, if rubbed on a counter or range top, or other material, makes a dark gray mark. If washed off the outside of the pan, it quickly forms again. A commercial process called "anodizing" thickens this coat and often colors it. Anodizing does not rub off. A special anodizing process produces a very hard, dark gray finish on professional type cookware.
Care depends on the product made from aluminum. Lacquers or waxes on products NOT used for food can protect aluminum against weathering and corrosion. Brighten aluminum utensils by cooking acid foods such as tomatoes, apples or rhubarb, or by boiling either 1 to 2 teaspoons cream of tartar per quart of water or 2 tablespoons vinegar per quart of water for 10 minutes in the pan. Prevent discoloration in the bottoms of double boilers or egg poachers by adding 1 teaspoon vinegar or 1/4 teaspoon cream of tartar to the water in the bottom pan. Remove stains from the outside of aluminum pans with silver polish, or mild, nonabrasive cleaner. Soap-filled steel wool pads scratch the outside surface, so use only when removing burned-on food or grease is more important to you than the scratched pan. Remove hard water mineral deposits (lime scale) from tea kettles where they have become crusted, boiling equal parts of vinegar and water for several minutes and letting stand an hour or so. The process may have to be repeated in severe cases. Rinse with plain water before using tea kettle.

Burned-on Food or Grease: Fill pan with hot water and let stand 1 hour. Scrape off as much food as possible with a dull item such as a wooden spoon or half of clothespin, or plastic spatula or plastic sponge. Complete removal with soap-filled steel wool pad. For grease build-up, soak in very hot water with detergent; then scour with soap-filled steel wool pad.
Use mild a detergent and warm water when possible. Alkalis, even baking soda, and especially stronger alkalis discolor aluminum. If trying a stronger cleaner, pre-test on a hidden place to be sure it cleans satisfactorily and does not damage the aluminum. Always follow directions on the product label for aluminum exactly. Be cautious about using abrasive cleaners (scouring powders, steel wool, abrasive polishes, etc.) as they may permanently scratch aluminum; painted or anodized aluminum surfaces will be permanently damaged. Do not clean aluminum when it is too hot to touch, or if temperatures go below 50 F.

On outdoor surfaces, remove bugs, sap, tree seeds, etc. as soon as possible, as they harden with exposure to sunlight and heat, and so are harder to get off. Suitable solvents will remove tar and similar substances. Test solvent first if the aluminum is painted to be sure it doesn't also remove the paint. Follow label precautions when using solvents. Make sure
theres no on spark or flame in the area and have sufficient ventilation.

Discolored Aluminum: Heat a solution of 1 tbs. vinegar per qt of water or 2 tsp. cream of tartar per qt of water in each pan until discoloration disappears.
Vinegar: To clean an aluminum coffeepot and remove lime deposits, boil equal pans of water and white vinegar. Boiling time depends upon how heavy deposits are.