•Gordon T Pearson, Conservation of Clay and Chalk Buildings, Donhead, Shaftesbury, 1992
•Gernot Minke, Earth Construction Handbook, WIT Press, Southampton, 2000
•Hubert Guillard and Hugo Houben, Earth Construction, Intermediate Technology Publications, London, 1994
scientific paper on clay plasters
Lowimpact.org plaster article(s)
If you are working with true clay plasters, there will be no VOC issues since you will not be using any. Molds grow in moist conditions, not the dry conditions needed for most clay and earthen plasters, which would limit where they could grow to exterior applications for the most part.
NOTE: it is possible to find clays that have toxic components such as lead, mercury and other heavy metals.
Redhawk