Why Does Baking Sheet/Pan Warp in Oven?

by iupilon

Baking sheets are made with multiple layers of metal clumped and shaped into pans that can fit various ovens and microwaves. Even though baking sheets can withstand high temperatures, these pans have their limits—baking sheets buckle inside the oven for one particular reason: extreme heat.

Basic knowledge of physics and chemistry will describe why baking sheets warp in the oven. When bakeware made of metal is placed at high temperature, the atoms move quickly until it expands. The unevenness of the molecules produces a way for the metals to warp. This phenomenon is the same with the breaking of ceramics at high temperatures, too.

Why Does Baking Sheet Warp in Oven?

Baking involves precision and constant monitoring of your bakeware and your heat source. The baking sheet may be heat resistant, but it is not prone to bending and warping. If left unobserved, the extreme heat may cause the baking sheet to lose its natural shape. The multiple layers of metal are clumped differently, with the four raised edges expands the slowest.

As the surfaces start to expand, the pan’s bottom expands faster than the other parts of the oven. This is because the bottom pan is located directly into the heated surface, making the metal molecules prone to rapid expansion. This pulls the composition of the baking sheet farther from its original shape. In return, the empty spaces cause enough stress on the folded edges.

Scientifically speaking, every object has atomic composition. The more atoms, the more solid it is. Metal molecules have a solid atom structure. Intense heat could make the atoms move faster and clump away from the heat source. In the baking sheet, the heat is collected on the pan’s bottom, making the edges and the inner side the cooler side of the pan.

This is why the metal atoms move further to the bottom of the pan, releasing a “passageway” for the metal to lose its structural integrity. This commonly happens faster on thinner baking sheets. If you hear the metal sheet popping and cracking in the oven, it is an initial sign of a baking sheet about to warp.

Purchasing a thicker baking sheet and checking your oven’s temperature are just a few of the precautions to prevent the baking sheet from warping. 

How Do I Keep My Baking Sheet from Warping?

Baking sheets are warping out for several reasons, including the temperature, cookware size, and material. Some baking sheets bend because of sudden temperature changes. If you overheat the material, it can also warp your bakeware. If the pan is too big or too thin for the specific heat source, it may bend. Aluminum pans and single-ply baking sheets are more vulnerable to warping.

Thermal shock

When a baking sheet has to endure thermal shock, it may expand and contract in the process—causing the dreaded warping. Thermal shock happens when the baking sheets are placed in an environment with unbearably quick temperature changes. Heating or cooling your baking sheet will rapidly change the overall construction of the metal baking sheet. This effect is also why heated glassware and ceramics crazed and breaks when cold water is placed.

High temperatures

If you cook your food at extreme temperatures, it can also induce thermal shock. Preheating your oven before placing cold cuts will create an uneven temperature. But, heating your baking pan too fast can also warp the bakeware. Placing your pan at high temperatures or preheating your pan will unevenly expand the baking pan—causing it to warp. If you happen to use a low-quality pan, it may not conduct and retain heat efficiently.

Pan is too big

There are also some situations that your baking pan is too big for the burner. This means that if the pan can almost reach the oven’s sides, it can distribute heat abnormally. This makes the pan more accessible to the heat source, making it heat faster. Getting the pan’s right size (wherein there is about an inch of allowance on each side) will prevent the baking pan from overheating.

Pan is too thin

Pans with thin walls or with thinner layers of metal will make it more possible to warp. Having lesser material is less sufficient in conducting the heat more evenly. Uneven heating is one of the major reasons why baking pans warp. Thinner pans also have more noticeable heat and cold spots that could induce warping when heated at higher temperatures.

Aluminum-based pans warp faster

Pans made with aluminum are more likely to warp than those made with stainless steel. Materials like aluminum and copper are softer, which has a looser molecular structure than some other solids. This gives an avenue to expand and contract the baking pans more easily. Pans made with cast iron and stainless steel have a tighter molecular structure, making them more resistant to higher temperatures.

Single-ply bakeware warps faster

Several bakewares are constructed with multiple layers of metal. If your baking sheet is not coated or mixed with several elements—it is only single-ply. Single-ply bakeware is only made with one material and costs cheaper than multi-ply baking pans. Purchasing specialized bakeware may reduce the warping effect better.

How Do You Fix a Warped Pan?

If you accidentally warped your baking pan, there are still ways to fix it. The methods are based on how worst the warping is. If it looks like twisted metal, there is no other way of flattening the metal. If the warping appears like tiny bumps or could not lay flat on an even surface, you may still fix a warped pan.

The simplest way to fix your warped baking pan is through the towel method. After placing your warped pan on a flat surface, lay a towel along the warped surface. The towel will serve as padding to incur additional damage. Warm your pan for 7 to 10 minutes so it won’t be shocked by the heat. Using a rubber mallet, gently tap the warped pan until it flattens. Please do not hit the pan hard, or it will leave thinner layers which can damage the pan further.

The second method is through the wood method. The baking pan will be heated until it is malleable. Instead of placing the woodblock while the pan is heating, it will only be placed after the heating process. This method is better if the bumps are larger and requires harder hitting. Place the heated baking pan on the wooden block and struck it until it flattens. Do the same thing on the baking pan’s other side if you feel that it is still uneven.

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