Folding is a specialized technique for combining two ingredients or mixtures, one of which usually has been aerated, such as whipped cream or egg whites. It is best done by placing the airy mixture on top of the other and with a rubber spatula, gently but quickly cutting through to the bottom and turning the ingredients over with a rolling motion. The bowl is rotated a quarter turn each time and the process repeated until the mixtures are combined, with as little loss in volume as possible. Care must be taken not to stir, beat or overmix. Fruit pieces, chips or nuts may be folded into an airy mixture using the same technique.