Deterioration Patterns Wallpaintings: Difference between revisions

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Author: [[user:NRiedl|Nicole Riedl]]<br>
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English Translation by [[user:Hschwarz|Hans-Jürgen Schwarz]] and [[user:SLeithaeuser|Sandra Leithäuser]]<br>


Author: [[user:NRiedl|Nicole Riedl]]<br><br>
back to [[Deterioration Patterns]]
back to [[Decay Pattern]]


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== Examples of damage by salt progression ==
== Examples of damage by salt crystallization ==


== Lime sinter crusts ==
== Calcareous concretions (sinter crusts) ==
[[file:Nehren Kalksinterkruste.jpg|thumb|300px|left| lime sinter crust,Roman wall-painting, Grave chamber, Nehren]]
[[file:Nehren Kalksinterkruste.jpg|thumb|300px|left| Calcareous concretion, Roman wall-painting, grave chamber, Nehren]]
[[file:Kalksinterkruste NWW Nehren.jpg|thumb|300px|right|lime sinter crust,Roman wall-painting, Grave chamber Nehren]]
[[file:Kalksinterkruste NWW Nehren.jpg|thumb|300px|right| Calcareous concretion, Roman wall-painting, grave chamber Nehren]]
Repeated precipitation of calcium carbonate formed on the surface of wall paintings a white, dense lime sinter crust. It is characterized by a high stability and strong bond with the painting. The vapour permeability of the wall painting is reduced and the crustal layers affect the aesthetic appearance considerably.
Precipitation of calcium carbonate on the surface of wall paintings generally begins by the formation of a fine white veil and may continue to form a white, dense calcareous concretion. It is characterized by its high stability and strong bonding with the painting. The water vapor permeability of the wall painting is reduced with the negative consequences that this may induce and the layered crust deposit(s) considerably affects their aesthetic appearance.
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== Cauliflower crust ==
== Framboidal efflorescence (cauliflower crust) ==
[[file:Blumenkohlkruste Nehren NWW Detail.jpg|thumb|300px|left|Cauliflower crust, Grave chamber Nehren]]
[[file:Blumenkohlkruste Nehren NWW Detail.jpg|thumb|300px|left|Framboidal efflorescence, grave chamber Nehren]]
[[file:Blumenkohlkruste Nehren NWW.jpg|thumb|300px|right|Blumenkohlkruste, Grave chamber Nehren]]
[[file:Blumenkohlkruste Nehren NWW.jpg|thumb|300px|right|Framboial efflorescence, grave chamber Nehren]]
Characteristic is the formation of firmly adhering Pustel?? and stable crusts. The composition may consist of calcium carbonate and calcium sulphate. Depending on the contaminants carried the cauliflower crust appear whitish, yellowish, reddish or brownish. Biogenic rests can be stored in the crustal layers.
The formation of firmly adhering framboidal efflorescence is characteristic for some conditions. The composition may consist of calcite (calcium carbonate) or gypsum (calcium sulfate dihydrate). Depending on the contaminants present, the efflorescence may appear whitish, yellowish, reddish or brownish. Biogenic material may be included within the crust deposits as they form.
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== Hygroscopic salts ==
== Hygroscopic salts ==
[[file:Gipskruste Hygroskopisch.jpg|thumb|300px|left|Gipskruste, hygroskopisch, Grabkammer Nehren]]
[[file:Gipskruste Hygroskopisch.jpg|thumb|300px|left|Gypsum crust and hygroscopic salts, grave chamber Nehren]]
[[file:Salzkruste Hygroskopisch Nehren.jpg|thumb|300px|right|Gipskruste, hygroskopisch, Grabkammer Nehren]]
[[file:Salzkruste Hygroskopisch Nehren.jpg|thumb|300px|right|Gypsum crust and hygroscopic salts, grave chamber Nehren]]
Innerhalb der flächigen Krustenablagerungen zeichnen sich entlang von feinen Rissen in der Malschicht und im Oberputz Verdunkelungen ab. Erhöhte Feuchtigkeit aus dem Putzmaterial oder aus der umgebenden Luft wird von den Salzkristallen gebunden und erscheint makroskopisch als dunkle, fleckige Anordnung.
The photograph shows darkened areas along fissures in the paint layer and topcoat of the plaster that also has crust deposits on it. This is caused by the presence of hygroscopic salts  that will tend to bind any moisture available in the plaster itself or originating from the ambient air. The moisture film will reflect light more giving the surface its darker appearance.  
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== Powdery salt deposits ==
== Powdery salt deposits ==
[[file:PulvrigeSalzkristalle-01.jpg|thumb|300px|left|Pulverförmige Salzausblühungen, Natriumsulfat, Grabkammer Nehren]]
[[file:PulvrigeSalzkristalle-01.jpg|thumb|300px|left| Powdery salt efflorescence, sodium sulfate, grave chamber Nehren]]
[[file:PulvrigeSalzkristalle-Natriumsulfat.jpg|thumb|300px|right|Pulverförmige Salzausblühungen, Natriumsulfat, Grabkammer Nehren]]
[[file:PulvrigeSalzkristalle-Natriumsulfat.jpg|thumb|300px|right| Powdery salt efflorescence, sodium sulfate, grave chamber Nehren]]
Weiße, locker anhaftende Salzausblühungen auf der Putz- und Malereioberfläche. Charakteristisch ist die Ausbildung von kleinkristallinen, weichen, pulverförmigen Salzen, die sehr unterschiedliche chemische Zusammensetzungen haben können. Beispielsweise Natriumsulfatablagerungen auf einem Ergänzungsputz aus Trasszement.
White, loosely adhering salt efflorescence on the plaster and the paint surface. It is characterized by small crystalline, soft, powdery efflorescence which may be formed by several different salts. The example shows sodium sulfate deposits on a repair plaster made with trass cement.
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== Scaling salt activity ==
== Scaling due to salt crystallization ==
[[file:Schalenbildung Nehren-01.jpg|thumb|300px|left|Schalenbildung, Grabkammer Nehren]]
[[file:Schalenbildung Nehren-01.jpg|thumb|300px|left|Scaling, grave chamber Nehren]]
[[file:Schalenbildung Nehren-02.jpg|thumb|300px|right|Schalenbildung, Grabkammer Nehren]]
[[file:Schalenbildung Nehren-02.jpg|thumb|300px|right|Scaling, grave chamber Nehren]]
Die auskristallisierenden Salze schädigen die Putzstruktur durch Absprengung. Während dem Phasenübergang von flüssiger Salzlösung zur Bildung von Salzkristallen dehnen sich diese aus und üben Druck auf die umgebende Putzmatrix aus. Dadurch werden ganze Putzschalen vom Untergrund abgehoben, sind mürbe und fragil.
The crystallizing salts can detach the paint layer and even the topcoat of the plaster. This occurs as a result of the liquid to solid phase transition during salt crystallization so that depending on where the salts crystals form, a thinner or a thicker layer may be detached.  
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[[Category:NRiedl]][[Category:DecayPattern_Wallpainting]] [[Category:R-HJuling]] [[Category:R-CBlaeuer]] [[Category:inProgress]]
[[Category:Riedl,Nicole]][[Category:Decay Pattern:Wall Paintings]] [[Category:R-HJuling]] [[Category:R-CBlaeuer]] [[Category:approved]]

Latest revision as of 11:00, 18 November 2013

Author: Nicole Riedl

English Translation by Hans-Jürgen Schwarz and Sandra Leithäuser

back to Deterioration Patterns


Examples of damage by salt crystallization[edit]

Calcareous concretions (sinter crusts)[edit]

Calcareous concretion, Roman wall-painting, grave chamber, Nehren
Calcareous concretion, Roman wall-painting, grave chamber Nehren

Precipitation of calcium carbonate on the surface of wall paintings generally begins by the formation of a fine white veil and may continue to form a white, dense calcareous concretion. It is characterized by its high stability and strong bonding with the painting. The water vapor permeability of the wall painting is reduced with the negative consequences that this may induce and the layered crust deposit(s) considerably affects their aesthetic appearance.

Framboidal efflorescence (cauliflower crust)[edit]

Framboidal efflorescence, grave chamber Nehren
Framboial efflorescence, grave chamber Nehren

The formation of firmly adhering framboidal efflorescence is characteristic for some conditions. The composition may consist of calcite (calcium carbonate) or gypsum (calcium sulfate dihydrate). Depending on the contaminants present, the efflorescence may appear whitish, yellowish, reddish or brownish. Biogenic material may be included within the crust deposits as they form.

Hygroscopic salts[edit]

Gypsum crust and hygroscopic salts, grave chamber Nehren
Gypsum crust and hygroscopic salts, grave chamber Nehren

The photograph shows darkened areas along fissures in the paint layer and topcoat of the plaster that also has crust deposits on it. This is caused by the presence of hygroscopic salts that will tend to bind any moisture available in the plaster itself or originating from the ambient air. The moisture film will reflect light more giving the surface its darker appearance.

Powdery salt deposits[edit]

Powdery salt efflorescence, sodium sulfate, grave chamber Nehren
Powdery salt efflorescence, sodium sulfate, grave chamber Nehren

White, loosely adhering salt efflorescence on the plaster and the paint surface. It is characterized by small crystalline, soft, powdery efflorescence which may be formed by several different salts. The example shows sodium sulfate deposits on a repair plaster made with trass cement.

Scaling due to salt crystallization[edit]

Scaling, grave chamber Nehren
Scaling, grave chamber Nehren

The crystallizing salts can detach the paint layer and even the topcoat of the plaster. This occurs as a result of the liquid to solid phase transition during salt crystallization so that depending on where the salts crystals form, a thinner or a thicker layer may be detached.