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BLACK CRUST
BLACK CRUST

Sample

Montjuïc sandstone (silicic sandstone)

Capitals of the Northern wing of  Sant Pau del Camp Cloister. Barcelona. Spain.  XIII century.


Pathology Causes

Particle and environmental pollutants deposition on thin layers of plaster-lime applied on the building during the XIX century. The crust has reacted chemically with the whitewash.


Visual Image

Author: Cetec-patrimoni

Description: General image of the hard black crust in contrast to washed areas in the intrados of the arch. The layer is formed by crust and whitewash and is partially separated from the stone substrate by subflorescences.
The capitals and the columns received different undocumented restorations during the XX century in which most of the whitewash was removed.


Image detail / macro

BLACK CRUST
BLACK CRUST
Author: Cetec-patrimoni
Magnification: x40

Description: On the obverse of the sample can be seen different brown and black shades, whose tone depends on the degree of deposition of pollutants. On the reverse, can be distinguished the thin layers of whitewash of the XIX century and salt efflorescence.


Microscope Image

BLACK CRUST
Author: Cetec-patrimoni
Magnification:

Description: From left to right: the texture of the Montjuïc sandstone, two layers of whitewash and black crust.


Associated Pathologies

Salt efflorescence.

Flaking.


Bibliography

ICOMOS-ICS (2008). Illustrated glossary on stone deterioration pattern.

http://international.icomos.org/publications/monuments_and_sites/15/pdf/Monuments_and_Sites_15_ISCS_Glossary_Stone.pdf 

 

ORDAZ, J., & ESBERT, R. (1988). Glosario de términos relacionados con el deterioro de las piedras de construcción. Materiales de Construcción, 38 (209): 39-45. doi: 10.3989/mc.1988.v38.i209.847


Author

Manuel Iglesias Campos. manuel.iglesias@cetec-patrimoni.com

Restorer


Institution or Company

Universitat de Barcelona


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