High calcium quicklime (Calcium Oxide) for limewash and hot mortar mixes. Building limes have been used as binders in mortars and plasters for thousands of years.
The introduction of cement in the middle of the 19th century led to the decline in the use of lime, and it virtually disappeared by the mid 20th century. Later evidence emerged that cement mortars, modern plasters, and modern paints damage historic building fabric. This led to a revival in the use of lime in recent years, not only for conservation but also for new builds.
As as finish:Functional and beautiful, limewash is a breathable, weather resistant finish used external and internal plaster and masonry surfaces. It is easily maintainable, stable, and long-lasting. Ideal for use in cellars and barns, where lime's high pH makes it inhospitable to microbe growth. Oxide pigments can be added for colour.
Caution: Care must be taken when adding water to quicklime (slaking). An intense heat reaction occurs that can burn skin, eyes, etc. Wear appropriate protective clothing and mix in a steel bucket as the mixture can get very hot.
Mix to a thin cream consistency. There are many recipes and much advice in the historic conservation and natural building literature. Find a recipe and a method for application that suits your project needs.