Before carrying out most conservation work, an understanding of both original and subsequent materials is essential, and often dictates the course of treatment, both passive and active. In order to evaluate the potential factors of decay, it is essential to understand the nature of the original materials, together with any later additions (for example, consolidants, varnishes and waxes), and products of alteration and deterioration of the original materials.

Paint analysis:

To determine paint characteristics, pigment and media type UV fluorescence and polarized light microscopy is employed together with staining, micro-chemical, solubility and flame tests in order to establish the characteristics and composition of various organic and inorganic materials within paint and plaster samples.

Plaster analysis:

Plaster analysis is undertaken in order to determine the mix ratios of the various constituents, the aggregate characteristics and mode and, most essentially, the type of binder. Titrimetric, volumetric and gravimetric techniques are generally employed to determine the constituents and their relative proportions in plasters and mortars. Once established this enables the replication of suitable repair mortars and materials to be formulated. Analysis of later plaster repairs should also be undertaken, to identify repair mixes and potential hazards they may pose to the significant fabric.

Salt analysis:

Salts and salt migration cycles can have a severely detrimental impact on the content and fabric of a building. Analysis of the types of salts present can help to identify possible sources, and indicate optimum environmental conditions to prevent the cycle of deliquescence and crystallisation.

For the purpose of analysis, salts may be directly removed from pockets of efflorescence or extracted from plaster substrates. Standard anion analysis can be undertaken at Hirst Conservation’s laboratories, to establish whether concentrations of salts are significant. Should salt levels be significant, sophisticated techniques such as SEM, FTIR analysis and ion chromatography may be recommended to identify salt types and characteristics conclusively.

 The results of this analysis can be correlated with the hygrometric parameters within the building environment and the hydrodynamics within the walls, as well as indicate the possible source/s of salts and their significance regarding mechanisms of deterioration.