Although copper pans have been used by cooks for centuries, in the 1950s their use declined in favor of stainless steel pots and pans. Though home cooks' preference switched to stainless steel, professional chefs still used copper pans quite often, due to how well and evenly they conduct heat. With the rise in popularity of television cooking shows that feature the use of copper pans, they have come back into use by the home chef once again. With a bit of preparation, baking with copper pans is fairly easy.
Confirm your copper pan is lined on the inside--typically with tin, but it also can be lined with stainless steel and nickel. The acidic nature of copper can react with certain foods, such as tomatoes and citrus juices, creating copper oxides. Although not fatal, ingesting copper oxides will give you a stomach ache. To prevent this, copper pans are lined with various materials to separate the food from the copper.
Adjust the cooking time for recipes when baking in a copper pan. Because of how efficiently they conduct heat, food will bake faster in a copper pan, and you risk burning it if you fail to adjust your cooking time accordingly. For example, if a quick bread recipe calls for a baking time of 35 minutes in a standard pan, you should check the bread at 20 minutes in a copper pan to see if it's already done.
Remove food baked in a copper pan with a wooden spatula rather than a metal one to avoid scratching it. Loosen the edges of cakes baked in copper pans with a wooden dowel instead of running a metal knife along the edge of the pan.
Avoid storing food or allowing food to sit in a copper pan for more than 2 hours. The food will take on a metal taste if allowed to sit in a copper pan for several hours.