Mortar may be made from burnt limestone, clay or a mixture of both as the bulk material. To that a sand or sometime grog filler is added. The amount and sorting of the added filler vary. In addition, mortar often contains different kinds of pollutions inherent from the limestone or introduced during the burning of the lime which may have a profound influence on the quality and functionality of the
mortar – i.e. a hydraulic mortar which is clay-polluted and behaves like concrete. The degree of homogenization of the filler in the mortar and the distribution and sizes of cavities and crack systems reflects the quality of the masonry.

In many ways, mortar is similar to pottery in complexity and compositional idea which means that the same analytic methods are applicable. Microscope analysis of thin sections is the most important method as the structure, functionality and actual function (draining rain water and other moisture).

The most common and most established research question regarding mortar analysis concerns the synchronization of different building phases in a multi-period construction. Concurrent building work in different places will tend to use the same raw materials and probably the same mixture of the mortar. Provenance determinations for the limestone have been discussed using different analytical methods including chemical. However, historical information on production locations and trade has often proven to be the most important source for establishing provenance. For restoration work, a mortar analysis provides important information that enables the production of new mortar with the original composition.