Lime Plastering a Cob Oven

Part Four shows how to apply a lime plaster to your cob oven. Lime plaster is made with 3 parts mason's sand and one part lime putty. I use Mississippi vertical hydrate lime, purchased as a powder, and I let it soak in water for a minimum of 6 weeks, until it is the consistency of sour cream. The longer it sits in water, the creamier and nicer to work with it becomes. LIME IS CAUSTIC! So be sure to wear protective clothing and gloves. Never touch it directly! My lime plaster bible is the book "Building with Lime" by Stafford Holmes and Michael Wingate.

You can also keep your oven dry with a roof or with clay plaster. Clay plaster will perform better in weather if it has wheat paste or manure added to it. Either way, plan to spend an hour or two repairing the clay plaster once a year.