Sheet pans, baking trays or baking sheets are flat, rectangular metal pans used in an oven. They are often used for baking bread rolls, pastries and flat products such as cookies, sheet cakes, and swiss rolls.
These pans, like all bakeware, can be made of a variety of materials, but are primarily aluminum or stainless steel. The most basic sheet pan is literally a sheet of metal. Common additional features that may be found in sheet pans include a lip on one or more edges to prevent food from sliding off, handles to aid in placing the pan into the oven, and removing it again, or a layer of insulation or air (air bake pan) designed to protect delicate food from burning.
Some bakers prefer to use a lining, rather than bake directly on a sheet pan, particularly for delicate or sticky pastries. Sometimes using no lining is better, and for many reasons: the linings or wrappers may have chemicals that get into the cake; research has shown that it takes less time to cook without a lining.
Sheet pans may be coated with a glaze to prevent food from sticking to their surface. When purchased with a glaze, sheet pans are often straightened and/or re-coated with glaze.