At Lancaster Lime Works, we recommend using lime plaster primer before any plaster work. Prime your drywall, old plaster, and latex paint walls to ensure proper adhesion of lime plasters. Primer San Tommaso is to be used on porous and semi-porous surfaces. Primer Plus is for non porous surfaces such as super smooth plaster, gloss and semi gloss paints and insulating foam board. Contact us for more information on lime plaster primers and we will be happy to answer any of your questions!