In contact with humidity, copper might oxidise. This oxidation is toxic; as a consequence, it is important to avoid any contact between food and copper during the cooking. This is why de Buyer utensils made of copper are, for most of them, lined with stainless steel, or tinned. Our Prima Matera, Inocuivre, Inocuivre VIP and Inocuivre First Classe cooking ranges are made of 90% outer copper and 10% inner stainless steel. This proportion is ideal and guarantees exceptional cooking properties.
Exception: copper is not harmful when it is used to beat eggs white or to cook sugar. As a result, egg-white hemispherical bowls, jam pans and sugar saucepans are neither tinned nor lined with stainless steel.