And stone visible lesions and classification
All of the stone, if exposed to the atmosphere, there will be disease. In order to better protect historical and cultural heritage, in particular for the protection of good and natural stone-related historical and cultural heritage and modern architecture, Italy research institutions in accordance with the definition of NORMAL 1/85 specification, based on the role of various lesions on the stone, natural stone lesions that appear on the following categories and indicate the definition of every form of disease.
1 conditions did not worsen class
(1) color change (chromatic alteration): decided to natural changes in the composition of the stone in the color parameter. Will expand to the whole rock, if the change is localized, is known as color spots (Macchia).
(2) the stain (staining, chromatic alteration): the specific nature of the material components (pyrite concentrate in marble) or external materials (water, oxidation of metallic materials, organic compounds, coatings) in relevant local colouring.
(3) in Pseudomonas aeruginosa (Patina): independent of the particular phenomenon of natural variation, and let people feel that the original color of the material changes.
Category 2 material loss
(1) erosion (surface erosion, surfacereduction, roughening): most of the material removed is the density of the surface.
(2) differences in erosion (differential erosion]): evident in stone constituted or typical structural heterogeneity.
(3) the pitting, erosion (pitting): formation of adjacent blind holes. Holes are mainly hemispherical, maximum a few millimeters in diameter.
(4) the corrosion pit, cellular decay (alveolization, honeycomb, cavernous decay): form hollow trough-shaped, size small, also known as the small bubble nest, often connected, is unevenly distributed.
3 profile damaged class
(1) breakdown (disaggregation, granular disintegration, crumbling): material formed powder or tiny crumbs fall off and peeling.
(2) exfoliation, scale off (exfoliation, contour scaling, flaking): formed one or more slices, the thickness is very small.
(3) skin (scaling, spalling): is often as original material decomposing, irregular, uneven thickness of sheet separation.
(4) separation (detachment): material between the surface layer or decomposition between upper and lower, are generally indicates these layers will fall off. On the stone, and separation of the part based on the characteristics of structure and texture often have specific shapes, such as spalling, scale off, crusts.
(5) loss, deletion (loss): three dimensional components missing (such as the arm of the statue, Roman ears fine jug ears, relief-decorated fragments, etc).
(6) the cavity, pore (lacuna): mainly with the development of two-dimension the missing parts (such as part-timbered and part paint part or part of a mortar or ceramic finishes, mosaic inlays, etc).