Limewash bonds by soaking into a porous mineral surface. Latex and acrylic paints and bare drywall paper do not give it enough to grip, so the walls need the primer system the chosen product specifies. New drywall usually takes a drywall primer before a mineral or bonding primer; sound painted walls often need only the bonding coat. Some primers can be tinted toward the final color, so thin areas of limewash do not flash a stark white beneath.
Before priming, walls are washed of grease and dust, repairs are filled and sanded, and existing paint is checked for soundness. Glossy enamels may need sanding. Paint that is peeling or chalky has to be removed or stabilized, because the limewash is only as sound as the layer under it. Some limewash lines are made only for unpainted masonry and are not used on drywall at all.