Comparative study of dark patinas on granitic outcrops and buildings

Biocidal effect of lichen secondary metabolites against rock-dwelling microcolonial fungi, cyanobacteria and green algae

“…Although the blackening of buildings and monuments can be also related to anthropogenic causes, as the deposition of gases and particles or sulphation mechanisms (Prieto et al, 2007), microorganisms as dematiaceous meristematic fungi, including microcolonial fungi (MCF), filamentous and coccoid cyanobacteria and, subordinately, green algae are also recognized as common agents of such threat to conservation (Gorbushina and Broughton, 2009;Macedo et al, 2009;Sterflinger, 2010). These organisms determine anaesthetic discoloration because of their dark pigments (Scheerer et al, 2009) and are often associated to physical and chemical deterioration processes because of their mechanical penetration and the release of acidic and chelating compounds (Macedo et al, 2009;Sterflinger, 2010;Favero-Longo et al, 2011).…”

“…In order to assay the potential applicability of the investigated LSM to control biological patinas on the stone cultural heritage, their interaction with a historical and culturally significant stone material (the white Carrara marble) was analysed with regard to the chromatic alteration, having a high relevance in stone conservation (Prieto et al, 2007;Tretiach et al, 2007). The necessity to perform further tests on the effects of LSM on other physico-chemical properties of stone materials and to assess their biocide effects in situ, i.e.…”

Biocidal Effect of Gamma Radiation on the Ecology of Filamentous Fungal Populations Associated with Stone Deterioration

“…This explains the direct effect of radiation, which is the dominant process when dry spores of microorganisms are irradiated [7]. The use of stone in the construction of monuments and sculptures has had some consequences over time, like the appearance of patinas [8] such as black films or biofilms [9]. These patinas have been identified in granite substrates [10][11][12], marble [13], all over the world, like Italian stone monuments [14] and historical monuments in Brazil [15][16][17].…”

“…In relation to block A (Fig. 3), the following elements were detected: 6 C, 8 O, 12 Mg, 13 Al, 14 Si, 20 Ca, 24 Cr, 25 Mn and 26 Fe. The analysis of block B showed the same chemical components, except for the absence of manganese: 6 C, 8 O, 12 Mg, 13 Al, 14 Si, 20 Ca, 24 Cr and 26 Fe.…”

Origen y efectos deteriorantes del yeso en monumentos graníticos del noroeste de España

“…El granito es una piedra polimineral, considerada poco noble como material arquitectónico y escultórico en épocas antiguas, por lo que se recubría con revestimientos, enlucidos o policromías. En un estudio reciente sobre pátinas negras desarrolladas sobre rocas graníticas (20), se encontró que en las ciudades de Santiago y La Coruña la mayoría de las pátinas poseen yeso como principal componente, tanto las que corresponden a monumentos como las que se encuentran en casas particulares sin ningún elemento escultórico; descartándose la procedencia de este mineral por contaminación atmosférica, se llegó a la conclusión de que, en estos casos, las pátinas se formaron a partir de antiguos revestimientos de las paredes que se fueron degradando, ensuciando y colonizando por microorganismos.…”