Rediscovering clay mortars

In areas where lime is in short supply, the most common substitute is the local clay which is found in pockets or as a major constituent of the subsoil over large areas of granite landscapes. When crushed and puddled with water, sand is added and the mortar begins to take shape. The mortars can be mixed with lime or animal slurry or manure to improve workability and the required texture. In a recent test, the mortars are likely allowing gradual water movement within masonry.