Notice catalographique « Development of an evaluation methodology for cleaning damage assessment : final report »
- Titre
- Development of an evaluation methodology for cleaning damage assessment : final report
- Auteur ou éditeur
- Charola, A. Elena
- Smithsonian Institution. Conservation Analytical Laboratory
- National Park Service
- Maison d'édition
- Smithsonian Institute. Conservation Analytical Laboratory
- Date de publication
- 1996
- Collation
- 154 p. : ill. ; 28 cm.
- Résumé
- The aim of the project was to determine an appropriate methodology for evaluation of damage induced during cleaning of masonry materials. Of the techniques used for the evaluation of surface changes, measurement of roughness appeared to be most promising. After a literature survey was conducted, a number of methods were explored, including white light interferometry, thermographic imaging, reflectometry, laser triangulation profilometry, stylus profilometry, and reflected light image analysis. This was followed by careful evaluation of the last three techniques on a set of three samples prepared in the laboratory: polished marble, sawn limestone, and a brick paver. Portions of each sample were abraded with glass beads or alumina powder, and silicone rubber replicas were prepared for laser triangulation profilometry (LTP) and reflected light image analysis (RLIA). Results of testing these samples showed that stylus profilometry and RLIA gave results consistent with LTP, which seemed the most accurate technique except on polished surfaces, but was unavailable for further tests. These two techniques were then used on a second, larger set of samples (polished marble, sawn marble, polished granite, flame finished granite, sawn limestone, sawn sandstone, quarry tile and glazed tile) blasted with water or powdered materials (walnut shells, glass beads, Black Beauty slag) at two pressures. In addition, reflectometry was used for evaluation of gloss on polished surfaces. To gain further insight about changes, a microdrop absorption test was used on porous surfaces, and visual and touch evaluations were also carried out. Results showed that none of the instrumental techniques is ideal for assessing changes in roughness of masonry materials induced by blasting. Stylus profilometry, as measured with a portable instrument, cannot be used to measure very rough surfaces. RLIA has the advantage that large surfaces can be evaluated, but interpretation of results is complex and use of replicas is mandatory. Microdrop absorption tests confirmed damaged induced by the harshest abrasives. Touch and especially visual evaluation of surfaces showed that if the appropriate standards were available, consisting of a range of samles for each type of stone, these methods could be applied successfully to evaluate change in roughness. Surface roughness of masonry materials is in general irregular because of inhomogeneities in the material itself and inconsistent application of surface finishes. Finally, the evaluation of roughness does not necessarily reflect the damage that abrasive cleaning methods can induce on stone.
- Langue
- English = Anglais
- Sujet
- Masonry - Conservation and restoration
- Masonry - Testing
- Maçonnerie - Conservation et resatauration
- Maçonnerie - Essais
- Pays
- United States
- Type de document
- Monograph = Monographie
- Localisation
- TH 3411 C43 1996
- Clé
- 17580
- Collection
- Catalogue