i) Select and evaluate methods of assessing the surface condition of stone work and determine the need for the application of surface treatments.

It is proposed to survey the available methods and test them (a) in the laboratory and (b) in the field. The criteria for assessment are that methods must provide unambiguous data which may be collated to the condition of the stone surface and at the same time be economic and practical.

ii) Examine the efficacy or re-treating a previously treated and subsequently weathered stone surface.

Re-treatment will not necessarily be as effective as treatment of weathered stone in the first place. Moreover, the best results may not necessarily be obtained for the same materials. Some of the best materials will be used for the re-treatment and new materials will be developed.


The project will include the following research tasks:

- Methods to assess the sate of treated and weathered stone work

- Preparation of stone samples having first treatment and weathering

- Assessment of first weathered treatments

- Re-treatment of stone samples and evaluation (by different treatments)

- Preparation of conclusions and recommendations.

Factors that have to be considered include preparatory cleaning of the weathered surfaces and interaction with the re-treatment material. The tests will be evaluated in two stages. Initial tests will be on specially prepared samples in the laboratory, to establish fundamental aspects of the equipments' performance. The equipment will then be evaluated against an old structure in the field, to establish its practicality.

Samples of old and weathered stone will be treated and artificially weathered. Materials used for the treatments will be an ethyl ester and an altoxy an altoxy silane, typical of those used a fifteen years ago and now coming to the time when they require attention. The state of the weathering will be evaluated. The samples will then be cleaned and re-treated using (a) the best materials developed in recent research, and (b) water based and solvent based materials to be specially developed in the present project.