Solid stone – surface damage or deterioration
Listed under: Exterior, masonry, stone, cladding, walls, wall cladding, solid stone and stone veneer
Cause
Air-borne pollution, dust or dirt combined with rain causing acid attack on the stone – particularly susceptible are limestone and Oamaru stone
Repair
- if damage is severe or the appearance is unacceptable, contact the stone supplier for advice. Restoration of acid-damaged stone surfaces is possible but is best done by experts
- be aware that many stones are porous, and preventing damage or staining in the first place is a better idea than trying to clean or repair it after it has happened
- house and gutter design and maintenance must ensure that there are no localised high-level flows of rainwater being chanelled down any stone surface. Over time this can result in damage or staining that can be impossible to clean away
- stone walls should be washed once a year with water and mild detergent using a sponge or soft-bristled brush. A low-pressure garden hose can remove any detergent residue. Don't use chemicals, abrasive cleaners, hard brushes or high-pressure water blasters as they can potentially damage the stone surface
Cause
Oxidation of impurities in the stone
Repair
- as for the first repair above