Brown sugar is a sucrose sugar product with a distinctive brown color due to the presence of molasses. It is either an unrefined or partially refined soft sugar consisting of sugar crystals with some residual molasses content or produced by the addition of molasses to refined white sugar. Brown sugar contains from 3.5% molasses (light brown sugar) to 6.5% molasses (dark brown sugar). The product is naturally moist from the hygroscopic nature of the molasses and is often labelled as "soft." The product may undergo processing to give a product that flows better for industrial handling. The addition of dyes and/or other chemicals may be permitted in some areas or for industrial products. Particle size is variable but generally less than granulated white sugar. Products for industrial use (e.g. the industrial production of cakes) may be based on caster sugar which has crystals of approximately 0.35 mm.