Costco Customers Share This Warning About Its Popular Under-$20 Baking Sheet Set

We may receive a commission on purchases made from links.

If you're looking for affordable, long-lasting, restaurant-quality baking sheets that can keep up with your busy kitchen, Costco's the place to go. One of the warehouse chain's better buys right now is the Tramontina Aluminum Baking Sheet Pan set, which comes in a pack of three for just $15.99. And with an average 4.6-star rating based on 400 reviews, you know it's a great value. However, it's not without its faults.

Even though it has 325 five-star reviews, some of those acknowledge that these pans, like some other kitchen items, should never go in the dishwasher. Many customers complain that after putting them in the dishwasher, the pans became pitted, discolored, and essentially ruined. "I've had to buy them a few times because my family keeps putting them in the dishwasher, but they can only be hand-washed. Other than that, they are great and so inexpensive," states a five-star reviewer on Costco's website.

Despite many customers loving their smaller size (9.5 inches by 13 inches) and durability, some say they wish the pans could be loaded in the dishwasher for easier cleaning. "The only thing I would change would be to make them from stainless steel. That would make them dishwasher-friendly," states a four-star reviewer. While you could technically return them, especially since the product description doesn't make it clear it's not dishwasher-friendly, most reviewers agree they're a great deal as long as you're willing to stick to hand washing.

Now that you know a dishwasher could damage your baking sheet, it's time to find some solutions to keep them functional and spotless for years to come. Chemicals in dishwasher detergents are mortal enemies of natural, uncoated aluminum, like the Tramontina Aluminum Baking Sheets. Along with the prolonged exposure to hot water and strong jets, the harsh detergent can strip and damage aluminum's natural protective oxide coating.

Instead, it's best to hand-wash these pans with warm water, mild dish soap, and a soft sponge to help preserve the pan's finish. But keep in mind, abrasive cleaners and rough scrubbing pads can scratch the surface and wear the baking pans faster over time. Even leaving them to soak too long in soapy water can lead to oxidation and discoloration. 

If you do find that you have some discoloration, baking soda can help; just make sure to take caution when using baking soda to clean aluminum pans. Gently rubbing a paste made from baking soda and water with a soft material can help remove stains. For tougher stains, adding a bit of hydrogen peroxide to the mix may also help. A bit of Barkeeper's Friend, which you can find on Amazon starting at $15, can also do the job — just be sure to wipe it with a soft rag and don't leave it on for more than a couple of minutes. With the right care and a little regular maintenance, these affordable baking sheets can stay in great shape for years.