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<bibimport />  
<!--Please check on my translations in the Glossary section- I have researched some terms, but am not entirely sure. -->
Author: [[user:Hschwarz|Hans-Jürgen Schwarz]]
<!-- The English version of this text was edited by Sandra Leithäuser-->
<br> <br>
 
Author: [[user:Hschwarz|Hans-Jürgen Schwarz]]<br>
English version by Sandra Leithäuser
<br>  
back to [[SaltWiki:Community_portal|SaltWiki:Portal]]
back to [[SaltWiki:Community_portal|SaltWiki:Portal]]
<br><br>


This page is under construction and will be published soon.
== Introduction ==
 
<!--
== Überblick über das Themenfeld "Schadensbilder" ==
 


Um neue Schäden beurteilen zu können, sind gut dokumentierte und analysierte Schadensbilder von großer Bedeutung. Die Schadenssammlung gibt einen Überblick, welche Schäden bisher an den unterschiedlichen Materialgruppen beobachtet wurden und wie man sich diese Schäden erklärt, um Schadensbilder neuer Schadensfälls besser und schneller analysieren zu können.  
Well documented and well analyzed deterioration patterns are of great importance for the assessment of new damage. This article provides an overview of deterioration patterns, that have been observed in the different material groups.
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<br>
Bisher liegen folgende Seiten zu Schadensbildern vor:


*[[Naturstein]]  
Material based collections of decay patterns are available for:
*[[Putze]]  
<!--
*[[Mörtel]]  
* [[Stone]]
*[[Baukeramik]]  
* [[Architectural Ceramics]], [[Plaster]], [[Rendering]]
*[[Metall]]  
* [[Metal]]
*[[Organische Materialien]]  
* [[Ceramic Materials]], [[Glass]]
*[[Keramische Materialien]]  
* [[Organic Materials]]  
*[[Glas]]  
-->
*[[Sonstige Materialien]]
* [[Building Materials]]
* [[Deterioration Patterns Wallpaintings|Wall Paintings]]


*[[Wandmalerei]]
== Glossary of Salt Efflorescences  ==


== Beschreibung von Ausblühungen auskristallisierter Salze  ==


An den Objekten, insbesondeer Wandmalereien, Mörteln, Putze, Keramiken und Naturstein zeigen Salzausblühungen immer wieder bestimmte, typische Ausbildungen, die hier kurz charakterisiert werden sollen.
Efflorescences are whitish, powdery or whisker-like crystals on the surface of porous materials. In most cases efflorescences are poorly cohesive and in general they are constituted by soluble salt crystals. On wall paintings, mortar, plaster, ceramic and natural stone, efflorescences repeatedly display certain typical forms. These are briefly characterized as follows:
[[Datei:Arnold-Swi 04.jpg|thumb|200px|Whisker bilden lange dünne, z.T. gebogene Kristalle, hier NaCl Whisker (aus <bib id="Arnold.etal:1991"/>)]]
'''Whisker''' (=Haarkristalle): wenige µm dicke, bis cm - lange, stengelige, oft auch gebogene Kristalle. Unter besonderen Bedingungen können Kristalle, bei denen ein nadelförmiger Habitus sonst keineswegs typisch ist, in feinen, haarförmigen Individuen, den sog. Whisker wachsen. Whisker sind bei den verschiedensten Substanzen, Metallen, Salzen und anderen Verbindungen beobachtet worden. Ihre Durchmesser liegen zwischen 0.01 und 100µm, während ihre Länge die Größenordnung von Zentimetern erreichen kann. Sie wachsen bevorzugt in ihrer Längsrichtung, während der Anbau von Substanz auf den Seitenflächen entweder völlig unterdrückt ist oder in gewissem Maße noch nachträglich geschieht. Es gibt Whisker, die entlang ihrer Achse eine einzelne (oder auch wenige) Schraubenversetzung enthalten, die an der Spitze ein Spiralwachstum bewirkt, wobei das Material längs der Seitenfläche zur Spitze transportiert werden muss. Es gibt aber auch Whisker ohne Schraubenversetzungen, bei denen das bevorzugte Wachstum an der Spitze nach einem anderen Mechanismus zustande kommt. Schließlich gibt es auch Whisker, die nicht an der Spitze, sondern an ihrer Basis wachsen, den wachsenden Kristall gewissermaßen emporstemmend.  


<br clear = all>
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[[Datei:KNO3-SalzflaumKoenigslutter.jpg|thumb|200px|Salzflaum bestehend aus KNO<sub>3</sub>, die einzelnen Kristalle sind Whisker]]
'''Whiskers''': a few microns thick to centimeters long, columnar, often curved crystals. Under specific conditions, crystals, which do not typically exhibit needle-building habits, grow as fine, hair-like shapes, the so-called whiskers. Whiskers have been observed developing from a variety of substances, e.g., metals, salts, etc. Their diameters range between 0.01 and 100 microns, while their length can reach up to a few centimeters. They grow preferentially in the longitudinal direction, while the growth on the lateral crystal plane is either suppressed or, to some extent, still in progress. Some whiskers accommodate a single, or a few, screw dislocations along their axis, causing a spiral growth at the tip, so that material along the lateral plane has to be transported to the tip. Some whiskers do not have screw dislocations, where the preferred growth takes place at the top- caused by a different mechanism. Finally, there are whiskers that do not grow at the top, but at their base, pushing the growing crystal upwards.
<br> '''Salzflaum''': sehr lockere, wolle- oder watteartige Salzausblühungen, bestehend aus meist gebogenen Haarkristallen.
<br clear =all>
[[file:Arnold-Swi 04.jpg|thumb|left|400px|Whiskers are long, thin, sometimes curved crystals, here NaCl whiskers (from <bib id="Arnold.etal:1991"/>)]]  


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[[Datei:IdensenThenardit_ausbluehung_aussen.jpg|thumb|200px|Salzrasen auf einer Fuge; die einzelnen Kristalle sind Whisker]]
'''Salzrasen''': lockerer Belag nadeliger bis stengeliger, mehr oder weniger senkrecht zur Unterlage stehender, 0,1 bis mehrere Millimeter großer Whisker. Salzrasen sind oft erst im Streiflicht gut sichtbar.


<br> '''Feathery - Fluffy efflorescence''':  very loose, fluffy or cotton-like efflorescence, usually consisting of bent whiskers.
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[[Datei:Eilsum Gipsausbluehungen.jpg|thumb|200px|pulverige Ausblühungen von Natriumsulfat]]
[[file:KNO3-SalzflaumKoenigslutter.jpg|thumb|left|400px|Efflorescence made of KNO<sub>3</sub>, the crystals are whiskers]]
'''Pulverige Salzausblühungen''': weißer, mehliger, dichter oder lockerer bis flockiger Überzug. Pulverige Ausblühungen entstehen je nach Salzart unterschiedlich. Einige Salze, insbesondere die etwas schwerer löslichen wie Gips, welche dann schleierartig dicht auftreten, können von Anfang an in dieser sehr feinkristallinen Form ausblühen. Bei Natriumsulfat z. B. ist diese Form dagegen meist ein Zeichen dafür, dass es sich um ein Entwässerungsprodukt der ehemals wasserhaltigen Salzform handelt.


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[[Datei:Salzpusteln.jpg|thumb|200px|Salzbedingte Pusteln auf einer Wandmalerei]]
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'''Salzpusteln''': voneinander getrennte, lockere bis kompakte, bis etwa 1mm Durchmesser große Salzhäufchen oder -höcker.
'''Acicular crystals-bristly efflorescence''': loose columnar whiskers, more or less perpendicular to the surface, 0.1 to several millimeters long, often only visible in raking light.
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[[file:IdensenThenardit_ausbluehung_aussen.jpg|thumb|left|right|400px|Salt crystals on a masonry joint; the individual crystals are whiskers]]


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[[Datei:Treppe_bei_St.Andreas_Hildesheim_Salzkruste.jpg|thumb|200px|Salzkruste durch Streusalz verursacht]]
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'''Salzkruste''': kompakte, manchmal fest auf der Unterlage haftende Salzaggregate mit flächigem Zusammenhalt und von sehr unterschiedlicher Dicke (einige µm bis mm).
'''Powdery efflorescence''': white, mealy, loose to dense or fluffy coating. Powdery efflorescence will develop differently depending on the type of salt crystallizing. Some salts, especially the less soluble ones such as gypsum, can bloom in this very fine form as soon as they crystallize. However, in the case of sodium sulfate this form of efflorescence results from the dehydration of the originally hydrated salt.
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[[file:Eilsumpudrigeausbluehungen.jpg|thumb|left|400px|Powdery efflorescences of sodium sulfate]]


<br clear = all>
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'''Weiße lockere Salzkruste''' (zuckerartige Kruste): Sie besteht aus Aggregaten von mit bloßem Auge oder mit einer schwachen Lupe gut erkennbaren, glasklaren Kristallen. Zuckerförmige Krusten entstehen innerhalb eines Feuchtigkeitsfilms. Sie können aber auch Rekristallisate einer Salzausblühung sein, die bei einer entsprechenden Feuchtigkeitszunahme in der umgebenden Luft Wasser aufnahm und in Lösung ging und anschließend durch erneuten Klimawechsel, diesmal zu trockeneren Verhältnissen hin, wieder aus der Lösung auskristallisierte.  
<br clear = all>
'''Salt pustules''': separate, loose to compact salt crystals, to about 1 mm diameter.  
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[[file:Salzpusteln.jpg|thumb|left|400px|Salt-induced pustules on a wall painting]]


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[[Datei:REM Seidenglanzkruste-mittel.jpg|thumb|200px|REM Aufnahme einer Seidenglanzkruste]]
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'''Seidenglanzkrusten''': Flächige, matt glänzende Salzkruste. Dicke Seidenglanzkrusten aus Gips scheinen erst durch mehrmaliges Umkristallisieren und über längere Zeiträume hinweg zu entstehen.
'''Salt crust''' : crusts can be formed by soluble salts when they are highly concentrated developing salt aggregates with planar cohesion and very variable thicknesses (a few microns to mm)
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[[file:Treppe_bei_St.Andreas_Hildesheim_Salzkruste.jpg|thumb|left|400px|Salt crust caused by de-icing salt]]


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'''White loose crust''' (sugary crust): consists of individuals that are visible to the naked eye or low magnification as glass-clear crystals. Sugary crusts usually form in a moisture film. However, they can crystallize from a salt efflorescence that takes up water from the surrounding air, undergoing dissolution and followed by recrystallizing as the environment dries.
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[[file:Strahlsund Kochsalz-Kruste.jpg|thumb|left|400px| Halite crust on an exterior wall in Strahlsund]]


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[[Datei:Gips Blumenkohlkruste 2.jpg|thumb|200px|Blumenkohlartige Ausblühungen]]
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'''Blumenkohlkruste''': Kruste aus weißen, kugeligen Aggregaten, die eng zusammenliegen, so dass ihre Oberfläche derjenigen eines Blumenkohls gleicht. Blumenkohlkrusten entstehen bevorzugt an kleinen Fehlstellen (Rissen oder ähnlichem) auf der sonst relativ dichten Putzoberfläche.  
'''Satin crust''': flat, shiny crust of salt. Thick, shiny crusts of gypsum are formed only by repeated recrystallization cycles over longer periods of time.  
<br clear = all>
[[file:REM Seidenglanzkruste-mittel.jpg|thumb|left|400px|SEM photo of a satin like crust]]


<br clear = all>
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'''Framboidal or botroidal crusts''': crust of white, spherical aggregates- its surface resembles that of a raspberry or blackberry or even a cauliflower. Botroidal crusts occur preferentially along small defects (e.g., cracks) on an otherwise relatively dense plaster surface. They also can form as separate units on dense stones.
<br clear = all>
[[file:Gips Blumenkohlkruste 2.jpg|thumb|left|400px|Framboidal efflorescences]]


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'''Faserkruste:''' Kruste aus eng beieinander, senkrecht zur Wand stehenden, Haarkristallen. Sie entstehen in der Regel auf gut durchfeuchteten Trägern.  
<br clear = all>
'''Fibrous crust:''' crust composed of densely packed whiskers, perpendicular to the substrate. They usually develop on moist substrates.  


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== Tracht und Habitus ==
== Habit ==
 
*Die Größenverhältnisse der an einem Kristall vorhandenen Grundformen ergeben den Habitus eines Kristalls.


*Die Tracht eines Kristalls besteht in der Aufzählung aller am jeweiligen Kristall auftretenden Grundformen.
*The crystal habit describes the proportions and shape of crystals.  


<br> Verschiedentlich wechselt der Habitus eines Minerals in Abhängigkeit von den Bildungsbedingungen.  
<br> The habit of salts will change depending on the conditions during their formation.  


Bedingt durch die Kristallstruktur, auch durch Mineral und Flächenkombinationen, haben die Minerale z.T. eine typische, z.T. wechselnde räumliche Erscheinungsform. Verschiedentlich kann diese auch durch einseitiges Wachstum hervorgerufen werden. Wir beschreiben diese Mineralformen wie folgt:  
Due to the crystal structure and the typical mineral and surface combinations, salts change in their physical appearance. On occasions, changes can also be caused by unilateral growth. We describe these mineral forms as follows:  


*'''isometrische''' Formen, wenn die Entwicklung in allen drei Raumrichtungen etwa gleich groß ist, z.B. bei allen kubischen Kristallen
*'''isometric''' forms, if the development into all three spatial directions is approximately of the same size e.g.. all cubic crystals.  
*'''eindimensional gestreckte Formen''': säulenförmig, stengelig, nadelig, haarförmig, faserig, z. B. Turmalin, Rutil, Asbest
*'''one-dimensional elongated''' forms: columnar, acicular, hair-like (whisker), fibrous, such as tourmaline, rutile, asbestos.  
*'''zweidimensional gestreckte''' Formen: tafelig, plattig, blättrig, schuppig, besonders bei Schichtmineralien, z.B. Baryt oder Glimmer
*'''two-dimensional elongated''' forms: tabular, lamellar, foliated, scaly, micaceous, e.g.. barite and mica.
*'''dentrische''' Formen haben Minerale, wenn durch Wachstumsstörungen nur eine unvollständige, skelettartige Ausbildung möglich ist.
*'''dendritic''' forms occur in the case of an incomplete crystal growth, developing plant-like shapes.


<br>
<br>


== Ausbildung der Salzkristalle nach Arnold  ==
== Formation of salt crystals, according to Arnold  ==


Die Kristallmorphologie (Habitus) in Abhängigkeit von den vorliegenden Feuchteverhältnissen lässt sich nach <bib id="Arnold:1992" /> wie folgt in fünf Gruppen gliedern (vgl. Abbildung):  
According to <bib id="Arnold:1992" /> the crystal morphology (habit) can be subdivided into five groups depending on the moisture condition present (see figure):


a) Allseitig wachsende, große Kristalle mit Gleichgewichtsformen bilden sich auf nasser Unterlage, wobei die wachsenden Kristalle tief in die Lösung eingetaucht bleiben, die als dicker Lösungsfilm die ganze Oberfläche oder Teile davon bedeckt
a) Multidirectional growth, large crystals with equilibrium shapes are formed on a wet surface as long as the growing crystals are immersed in the solution. The solution covers the whole surface or parts of it as a dense film.


b) Eine körnige Kruste aus isometrischen Kristallen entsteht auf noch stark feuchtem Substrat, während die Kristalle mit dem Lösungsfilm überdeckt sind und allseitig wachsen
b) A granular crust of isometric crystals forms on a wet substrate, while the crystals are immersed in the solution film and are growing into multiple directions.


c) Eine Faserkruste bildet sich auf mittelfeuchtem Substrat, das von einem zusammenhängenden Lösungsfilm bedeckt wird. Die säuligen Kristalle wachsen an ihrem Fuß, wo sie noch im Kontakt mit der Nährlösung sind und werden emporgehoben.  
c) A fibrous crust forms on a medium moist substrate that is completely covered by the solution film. The columnar crystals grow from their base that is still in contact with the nutrient solution so that the dry crystals are moved upward.  


d) Dicke Whisker-ähnliche Kristalle wachsen auf der leicht feuchten Oberfläche aus kleinen Lösungsinselchen
d) Columnar, thick whisker-like crystals grow on the humid surface and out of small pools of the solution.


e) Sehr dünne Whisker aus "Lösungspünktchen" auf der nun fast trockenen Oberfläche. Daraus entsteht ein Salzflaum.  
e) Very thin whiskers grow out of "solution drops" on the now nearly dry surface. The result is a fluffy salt efflorescence.


Salze bilden bei ungestörter Kristallisation aus der Lösung ihre charakteristische Kristallform aus. Man spricht dann von idiomorphen Kristallen. Hypidiomorphe Kristalle bilden nur teilweise ihre Eigengestalt aus, während bei einer xenomorphe Kristallisation, die Kristallform keinerlei Beziehung zur Eigengestalt hat. [[Image:Salzkristallisation Feuchteregime.jpg|thumb|center|600px|Zusammenhang zwischen Kristallmorphologie und Feuchteregime, s.o. (nach <bib id=Arnold:1992/>) ]]
Salts can form their characteristic crystals under undisturbed crystallization conditions and when a sufficient supply of the salt solution is available. These crystals are called idiomorphic. Hypidiomorphic crystals are those that are only partially idiomorphic, while xenomorphic crystals refers to those whose shape does not resemble the intriinsic one.  
[[Image:Salzkristallisation Feuchteregime.jpg|thumb|center|600px|Relationship between crystal morphology and moisture regime (after <bib id="Arnold:1992"/>) ]]


== Literature ==
== Literature ==


<bibprint/>
<biblist/>


-->
 
[[Category:Hschwarz]][[Category:R-CBlaeuer]] [[Category:saltdamage]][[Category:inProgress]]
[[Category:Schwarz,Hans-Jürgen]][[Category:R-CBlaeuer]] [[Category:saltdamage]][[Category:approved]][[Category:Decay_Pattern:Others]][[Category:Decay_Pattern:Ceramics]][[Category:Decay_Pattern:Glas]][[Category:Decay_Pattern:Pottery]][[Category:Decay_Pattern:Metal]][[Category:Decay_Pattern:Plaster]][[Category:Decay_Pattern:Natural_Stone]][[Category:Alveolarweathering]][[Category:Decay_Pattern:Organic_Materials]][[Category:Decay_Pattern:Wall_Paintings]]

Latest revision as of 10:15, 19 March 2023


Author: Hans-Jürgen Schwarz
English version by Sandra Leithäuser
back to SaltWiki:Portal

Introduction[edit]

Well documented and well analyzed deterioration patterns are of great importance for the assessment of new damage. This article provides an overview of deterioration patterns, that have been observed in the different material groups.

Material based collections of decay patterns are available for:

Glossary of Salt Efflorescences[edit]

Efflorescences are whitish, powdery or whisker-like crystals on the surface of porous materials. In most cases efflorescences are poorly cohesive and in general they are constituted by soluble salt crystals. On wall paintings, mortar, plaster, ceramic and natural stone, efflorescences repeatedly display certain typical forms. These are briefly characterized as follows:


Whiskers: a few microns thick to centimeters long, columnar, often curved crystals. Under specific conditions, crystals, which do not typically exhibit needle-building habits, grow as fine, hair-like shapes, the so-called whiskers. Whiskers have been observed developing from a variety of substances, e.g., metals, salts, etc. Their diameters range between 0.01 and 100 microns, while their length can reach up to a few centimeters. They grow preferentially in the longitudinal direction, while the growth on the lateral crystal plane is either suppressed or, to some extent, still in progress. Some whiskers accommodate a single, or a few, screw dislocations along their axis, causing a spiral growth at the tip, so that material along the lateral plane has to be transported to the tip. Some whiskers do not have screw dislocations, where the preferred growth takes place at the top- caused by a different mechanism. Finally, there are whiskers that do not grow at the top, but at their base, pushing the growing crystal upwards.

Whiskers are long, thin, sometimes curved crystals, here NaCl whiskers (from [Arnold.etal:1991]Title: Monitoring Wall Paintings Affected by soluble Salts
Author: Arnold, Andreas; Zehnder, Konrad
Link to Google Scholar
)



Feathery - Fluffy efflorescence: very loose, fluffy or cotton-like efflorescence, usually consisting of bent whiskers.

Efflorescence made of KNO3, the crystals are whiskers



Acicular crystals-bristly efflorescence: loose columnar whiskers, more or less perpendicular to the surface, 0.1 to several millimeters long, often only visible in raking light.

Salt crystals on a masonry joint; the individual crystals are whiskers



Powdery efflorescence: white, mealy, loose to dense or fluffy coating. Powdery efflorescence will develop differently depending on the type of salt crystallizing. Some salts, especially the less soluble ones such as gypsum, can bloom in this very fine form as soon as they crystallize. However, in the case of sodium sulfate this form of efflorescence results from the dehydration of the originally hydrated salt.

Powdery efflorescences of sodium sulfate



Salt pustules: separate, loose to compact salt crystals, to about 1 mm diameter.

Salt-induced pustules on a wall painting



Salt crust : crusts can be formed by soluble salts when they are highly concentrated developing salt aggregates with planar cohesion and very variable thicknesses (a few microns to mm)

Salt crust caused by de-icing salt



White loose crust (sugary crust): consists of individuals that are visible to the naked eye or low magnification as glass-clear crystals. Sugary crusts usually form in a moisture film. However, they can crystallize from a salt efflorescence that takes up water from the surrounding air, undergoing dissolution and followed by recrystallizing as the environment dries.

Halite crust on an exterior wall in Strahlsund



Satin crust: flat, shiny crust of salt. Thick, shiny crusts of gypsum are formed only by repeated recrystallization cycles over longer periods of time.

SEM photo of a satin like crust



Framboidal or botroidal crusts: crust of white, spherical aggregates- its surface resembles that of a raspberry or blackberry or even a cauliflower. Botroidal crusts occur preferentially along small defects (e.g., cracks) on an otherwise relatively dense plaster surface. They also can form as separate units on dense stones.

Framboidal efflorescences



Fibrous crust: crust composed of densely packed whiskers, perpendicular to the substrate. They usually develop on moist substrates.


Habit[edit]

  • The crystal habit describes the proportions and shape of crystals.


The habit of salts will change depending on the conditions during their formation.

Due to the crystal structure and the typical mineral and surface combinations, salts change in their physical appearance. On occasions, changes can also be caused by unilateral growth. We describe these mineral forms as follows:

  • isometric forms, if the development into all three spatial directions is approximately of the same size e.g.. all cubic crystals.
  • one-dimensional elongated forms: columnar, acicular, hair-like (whisker), fibrous, such as tourmaline, rutile, asbestos.
  • two-dimensional elongated forms: tabular, lamellar, foliated, scaly, micaceous, e.g.. barite and mica.
  • dendritic forms occur in the case of an incomplete crystal growth, developing plant-like shapes.


Formation of salt crystals, according to Arnold[edit]

According to [Arnold:1992]Title: Salze: Lästige weiße Ausblühungen oder Hauptschadensursache?
Author: Arnold, Andreas
Link to Google Scholar
the crystal morphology (habit) can be subdivided into five groups depending on the moisture condition present (see figure):

a) Multidirectional growth, large crystals with equilibrium shapes are formed on a wet surface as long as the growing crystals are immersed in the solution. The solution covers the whole surface or parts of it as a dense film.

b) A granular crust of isometric crystals forms on a wet substrate, while the crystals are immersed in the solution film and are growing into multiple directions.

c) A fibrous crust forms on a medium moist substrate that is completely covered by the solution film. The columnar crystals grow from their base that is still in contact with the nutrient solution so that the dry crystals are moved upward.

d) Columnar, thick whisker-like crystals grow on the humid surface and out of small pools of the solution.

e) Very thin whiskers grow out of "solution drops" on the now nearly dry surface. The result is a fluffy salt efflorescence.

Salts can form their characteristic crystals under undisturbed crystallization conditions and when a sufficient supply of the salt solution is available. These crystals are called idiomorphic. Hypidiomorphic crystals are those that are only partially idiomorphic, while xenomorphic crystals refers to those whose shape does not resemble the intriinsic one.

Relationship between crystal morphology and moisture regime (after [Arnold:1992]Title: Salze: Lästige weiße Ausblühungen oder Hauptschadensursache?
Author: Arnold, Andreas
Link to Google Scholar
)

Literature[edit]

[Arnold.etal:1991]Arnold, Andreas; Zehnder, Konrad (1991): Monitoring Wall Paintings Affected by soluble Salts. In: Cather, Sharon (eds.): The Conservation of Wall Paintings: Proceedings of a symposium organized by the Coutrauld Institut of Art and the Getty Conservation Institute, London, July 13-16, The Getty Conservation Institute, 103-136.Link to Google Scholar
[Arnold:1992]Arnold, Andreas (1992): Salze: Lästige weiße Ausblühungen oder Hauptschadensursache?. In: Jahresberichte Steinzerfall - Steinkonservierung, 2 (), 1-9Link to Google Scholar