Typical machines used to make cotton candy include a spinning head enclosing a small "sugar reserve" bowl into which a charge of granulated, colored sugar (or separate sugar and food coloring) is poured. Heaters near the rim of the head melt the sugar, which is squeezed out through tiny holes by centrifugal force. Colored sugar packaged specially for the process is milled with melting characteristics and a crystal size optimized for the head and heated holes; granulated sugar used in baking contains fine crystals which spin out unmelted, while rock sugar crystals are too large to properly contact the heater, slowing the production of cotton candy.