Lime plastering is a traditional technique, composed of hydrated lime, sand, water, and sometimes finely chopped straw or hair for reinforcement. The ratio of material is 3 parts mason sand to 1 part lime and water to taste. Unlike earthen plasters lime is caustic so a trowel is the only way to apply the material to the wall. No hands! A hawk is a handy tool that holds the plaster as you spread it on the wall. Also, lime plasters get stronger over time and to assist in the process make sure the plaster dries at a slower rate by wetting the wall over a period of time. Once it’s dry, lime is more water resistant and durable than earth plaster, but still needs a suitable eave for protection. We lime plastered the future communal kitchen at Aprovecho. It went on gray but dried white, which makes for applying color a lot easier.