Ask Paul: Why are my baking pans warping?

Heat warps pans, and that’s nothing to worry about unless it’s impacting your baking. If that’s the case, I know a great place you can buy some pans.

Back to the question. Sheet pans are most prone to buckle due to the uneven expansion of the surfaces of the pan. Most sheet pans have turned-up continuous edges all around, so you have multiple surfaces, all expanding in the heat, with the greater the length the greater the amount of expansion.

The bottom of the sheet pan, being the longest of all, is trying to expand in an area that is restricted by the folded-up edges, resulting in the bottom buckling as it seeks to expand.

The loud popping sometimes heard in the oven is the pan suddenly giving in to the stress of the expansion. Once the pan is completely hot, the buckling will go away as the rest of pan catches up in expansion. The same thing can happen in reverse as the pan is moved into a much cooler area after baking.

Additionally, widely spaced food on a baking sheet creates varying temperatures across the metal, with some spots under the food shielded from heat and others fully exposed. These differences cause different contractions or expansions, which can cause buckling. This is inherent in the design of the pan and its heating method and no guarantee of freedom from this problem can be made.

However, this phenomenon is usually temporary and reversible, but sometimes these stresses are greater than the strength of the material, especially in thinner metal, which causes the pan to be permanently buckled or “warped.” Getting thicker pans helps some because the bottom becomes stronger and can begin to dominate the edge strength, but this alters the cooking.

If the oven has different top and bottom heat, or the pan is placed higher or lower in the oven, this will also alter the heat input, sometimes increasing and sometime reducing the difference, and can either make the buckling worse, or be used to reduce it.

A pan with only one folded edge does not suffer this condition, but now liquids cannot be contained.

So there you go. Pans can and will warp, especially sheet pans. Don’t worry unless it’s impacting baking. If it is, give us a call at 800-748-6251 or email us at sales@lloydpans.com.

Purchase your baking pans online today!