Mortar Analysis of historic plasters renders or building mortars with mortar specification and on-site samples


It is often useful before starting on the conservation or restoration of a historic building, to understand what materials have been used originally and through the different phases of its life, for the construction, plastering, and rendering. No job is the same and we offer a range of mortar analysis techniques. Often, we will undertake dissolution analysis of the mortars used, and based upon years of interpretive experience, we will detail the type of binders and aggregates used and their ratios and grading. This together with our recommendation for a replacement pointing, building mortar or render/plaster will often be sufficient for many jobs on listed and non-listed buildings and structures.

However, when more detail is required to understand the structure within the mortar, and further precise information on its hydraulic and clinker content is needed, additional thermogravimetric and petrographic mortar analysis is carried out.

The most important element of all these investigations is the interpretation of these results and Mark Womersley has over 25 years’ experience of analysing mortars, but as importantly, also has many years’ experience in their subsequent specification and use. This ensures that you not only find out which mortars have been used on your building, but also which ones should be used in future conservation work, that will let the building’s fabric breathe, be flexible enough for the substrates and be durable enough for the buildings location and detailing.

We can also prepare sample panels, or advise your contractors on which mortars to use and what options they have for creating different finishes and textures.


M. Womersleys works with a local University using the state-of-the-art equipment and techniques.



Dissolution Mortar Analysis

This is a very simple but effective form of analysis when carried out by our experinced team. The sample is examined by eye and under a microscope. The sample is then: dried, crushed, the binder disolved in acid, the residue is washed and filter, dried again and put through a set of sand seives.

Our subsequent report will suggest what the mortar was originally composed of  and suggest a specfication for repair or replacement.

The Cost is £95 plus vat with discounts for multiple samples



Thermogravimetric Mortar Analysis

This is a technique in which the mass of a substance is monitored as a function of temperature or time as the sample specimen is subjected to a controlled temperature program in a controlled atmosphere.

It is a technique in which, upon heating a material, its weight increases or decreases. A sample pan is supported by a precision balance. That pan resides in a furnace and is heated or cooled during the experiment. The mass of the sample is monitored during the experiment.

We can undertake the test on very small samples of mortar and determine the percentage of
nonhydraulic and hydraulic binders and effects of some pozzolana. Results take around a week to process. The cost is £150.00 plus vat.


Petrographic Mortar Report - High-power microscopy is undertaken

The submitted sample / specimens are examined as received, and after careful washing to remove loose debris, using a stereomicroscope. The main purpose of the preliminary examination is to identify the degree of consistency or variability in the submitted sample / specimens and any superficial evidence of deterioration. This facilitates the selection of the most appropriate specimen(s) for a full petrographic examination when multiple specimens of the same material type are submitted.

Following preliminary examination, the selected specimen is cut in half parallel or perpendicular with its axis (to suit the objectives of the investigation). One half of a cut specimen may be carefully ground, finishing with #600 grit carborundum powder. At least one standard petrographic thin section is prepared from each selected specimen. The cut specimen, used for section preparation, is typically vacuum impregnated with a low viscosity epoxy resin containing a yellow fluorescent dye. A high resolution, low magnification digital image of each thin section is prepared using a film scanner. This type of image is useful for illustrating the mesostructure of the material. The thin section(s) may be examined in both plain and cross-polarised light, and reflected ultraviolet light creating secondary fluorescence. Photomicrographs are taken using a high-resolution digital camera.

A report is prepared to identify the aggregate, binder and the changes to the binder matrix and its components that have occurred over time. Cost from £300 plus vat.



Preparation of pointing samples on the building

 If required, we can prepare on site samples drawing from a wide range of limes and types of aggregate and natural pozzolanas. Cost from £250 plus vat.