What Causes Pit Marks on Aluminum Bakeware?

Coatings

• Aluminum bakeware cooks food efficiently because aluminum conducts heat evenly and quickly. When one part of an aluminum pan heats, the energy flows to all other parts of the pan, preventing hot or cold spots. Coatings compensate for disadvantages of aluminum cookware, including pitting and scarring. Manufacturers protect some types of aluminum bakeware with hard anodizing, a process that deposits a thick layer of hard aluminum oxide on the surface of the pan. Heat-resistant teflon coatings also provide a slick cooking surface and protection from corrosion. As long as their coating remains flawless, aluminum baking pans won't pit.

Accessories

• Literature accompanying your bakeware specifies what types of cleaning tools and cooking utensils match the surface of the pots and pans. In general, use utensils made from either wood or nylon when working with coated aluminum bakeware. Scrape baked food out of the pans carefully, as rough treatment can damage the finish. Loosening baked-on food by soaking causes fewer problems than scraping, but use soft plastic or nylon scrubbers to clean the pan instead of scouring pads or steel wool. Unless the manufacturer notes otherwise, plastic finishes will safely endure dishwashers. The high heat and harsh cleansers of dishwashers might damage aluminum oxide coatings.

Damaging Foods

• Some types of food create pits in bare aluminum if left in contact with the metal for extended periods. Storing very acidic foods such as tomato sauce in aluminum containers leaches aluminum from the container walls. Any undissolved salt crystals left in the bottom of an aluminum pan corrode pits in the metal. Pickling lime severely corrodes aluminum, giving foods such as pickled garlic a greenish color if prepared in aluminum pans, according to the National Center for Home Food Preservation. Natural acids found in nutritious leafy greens such as kale and turnip greens can also pit aluminum.

Proper Care

• Many foods and cleaning agents only discolor aluminum and do no serious harm. Iron and sulfur in boiled eggs or potatoes boiled in their peels darkens an aluminum surface. Leaving an aluminum pan to soak in a detergent solution can permanently discolor the metal. Washing aluminum bakeware by hand saves the finish from dishwasher damage, and small scratches in plastic coatings might seal if sprayed with a repair compound that matches the original surface. Aluminum leaching into food from pitted cookware presents no health hazard, but the pits themselves harbor food residues and bacteria. If you can't clean food from deep pits, replace the pan.