Try this Royal Icing Recipe recipe, or contribute your own.
Royal icing achieves its characteristic hard-set finish through the structural transformation of dried albumin proteins rather than the evaporation of moisture alone. Confectioners' sugar provides the bulk sucrose, while meringue powder introduces dried egg whites containing water-soluble proteins that unfold during agitation and trap air bubbles. When combined with six tablespoons of warm water, these components hydrate rapidly to form a stable colloidal suspension that cures into a rigid lattice upon exposure to air. Maintaining strict sanitation of mixing bowls is critical, as any microscopic trace of residual fat will coat the protein strands and prevent proper mechanical aeration.
Controlling moisture levels dictates the working properties of the frosting. For precise outlining work, reduce the liquid volume by one tablespoon to yield a stiffer paste that holds sharp peaks without sagging. Conversely, incorporating water incrementally by the teaspoon transforms the mixture into a self-leveling consistency suitable for flooding surfaces. Because this formulation contains no dairy or animal fats, it accommodates vegan and vegetarian dietary requirements naturally when using certified plant-derived colorants. Stored properly in an airtight container lined with plastic wrap pressed directly against the surface, the mixture remains viable under refrigeration for at least thirty days.