For icings and fondant coating, often water soluble dyes are used. Lakes may be used where stability against heat and light is required. For cake batter liquid dyes can be used as they give a uniform color. For the dry mixes fine powder of the dye can be added. Care should be taken while beating the mix to maintain uniformity.
The oil based coatings can be coloured by lakes when the coating is in liquid form. The lakes should be allowed to disperse in the vegetable oil before coating. For cookie filling, again lakes are better and dyes considered incompatible as the base is fat and lakes disperse better in this medium than dyes.