To beat or whip egg whites, the type of bowl you use is important. Avoid plastic bowls, which, despite washing, can retain a grease film. Unlined copper bowls are best for turning out stable, voluminous whites. If beating whites in a glass or stainless steel bowl, you can help stabilise them by adding a pinch of cream of tartar. Whites are best beaten with a balloon whisk. Beat just until the whites are stiff but not dry.
