Aluminum conducts heat only about half as well as copper. This is still quite fast, however, and unlike copper, aluminum is inexpensive. Like copper, aluminum reacts with food, especially acidic foods. It discolors fruit products and turns milk and egg mixtures an unattractive gray, limiting its use in stovetop cookware. Aluminum mixer attachments also present a problem with reactive foods, discoloring some products. Since aluminum is a soft metal, it is easily scratched and pitted.
Why does Marble Feel Cool to the Touch, Even in a Warm Bakeshop?
Touch a marble surface with one hand and a wood surface with the other, and the marble will feel noticeably cooler to the touch. Yet both the marble and the wood, if they have been in the same room for a while, are at room temperature. How can this be?
Marble has greater heat conductivity than wood, so heat transfers faster from your body to marble than it does to wood. Because the hand touching marble cools more quickly, the marble seems cooler to the touch (when, in actuality, the marble is now slightly warmer, because heat has transferred to it from the hand).
Repeat this demonstration by placing one hand on marble and the other on stainless steel or another metal. Because metals have greater heat conductivity than marble, the stainless steel surface will seem cooler than the marble surface. Again, it seems cooler because heat transfers faster from the hand touching stainless steel than from the one touching marble.
Because of marble’s good heat conductivity, marble surfaces are often used in bakeshops to quickly cool hot confectionery products. Why not use a stainless-steel surface instead? Generally, the answer has to do with the price: the cost of stainless steel would be prohibitive. Because a thick stainless-steel table is very expensive to construct, these tables are typically thin, and thus they heat up too quickly. However, special stainless-steel cooling tables are available to confectionery manufacturers. These tables are designed to allow cooling water to circulate within a sandwich of stainless steel. Heat is quickly conducted through the stainless-steel surface to the water, where it is carried away through conduction and convection.
