A dull, dark, or black surface absorbs more of the radiant energy (IR) coming from the oven walls than a bright, shiny, or white surface, which reflects much of it. A black pan (carbon steel or a coated aluminum, for instance) will therefore become hotter and transmit heat more quickly than an otherwise identical uncoated stainless steel or aluminum pan in the same oven. This phenomenon explains why white suits and dresses are popular in hot, sunny weather. On the average, a shiny pan is 15F cooler in a 350F oven than its black equivalent, and that 15F can make a crucial difference. Because the shiny pan's temperature is lower, you must either extend the cooking time or increase the baking temperature. Neither of those two alternatives is totally satisfactory. No matter what the cooking temperature or how long the cooking time, chances are that either the exposed crust will receive too much heat or the crust that lines the pan will absorb too little heat. Shiny bakeware is not all that bad. It can be beneficial at times. Some delicate cookies require a very hot oven but are apt to burn on the bottom when baked on a dark, dull cookie sheet. A glistening cookie sheet, on the other hand, reduces the heat reaching the cookies' undersides - hence no burning. The parchment has no real effect on the pan's heat absorption because of its material and mass. It is likely mainly invisible to the IR radiation frequencies emitted by the burners in the oven. There is no mystery. It's just science! -Larry

• Reply