Talk:Salts Resulting from Restoration Materials: Difference between revisions

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Author:[[Benutzer:Hschwarz|Hans-Jürgen Schwarz]]
I moved the article to the text page [[User:Hschwarz|Hschwarz]] 13:31, 9 August 2012 (CEST)
<br> back to [[Origin of Salts]]  
 
 
==Restoration materials  ==
 
Many restoration materials contribute to the salt contamination of objects. Sometimes they can even be the main source of damage. 
 
Difficult are alkaline and acidic cleaning or restoration products such as:
 
 
=== Water glass ===
 
Water glass is used to consolidate surfaces. The following reactions can be visualized schematically:
 
Na<sub>2</sub>SiO<sub>3</sub> (Na-water glass) <nowiki>+</nowiki> CO<sub>2</sub> <nowiki>+</nowiki> H<sub>2</sub>O&nbsp; → SiO<sub>2</sub> <sub>Gel</sub> <nowiki>+</nowiki> Na<sub>2</sub>CO<sub>3</sub>
 
<br>
 
K<sub>2</sub>SiO<sub>3 </sub><sup></sup>(K-water glass)<sup></sup> + CO<sub>2</sub> + H<sub>2</sub>O → SiO<sub>2</sub> <sub>Gel</sub> + K<sub>2</sub>CO<sub>3</sub>
 
The resulting sodium carbonate can constitute up to 30% of water glass substance, the potassium carbonate up to 20%.
 
Potassium water glass: potassium carbonate is very hygroscopic and it is hardly ever found in its crystalline form. A subsequent reaction into potassium nitrate in contrast nearly always leads to efflorescence.
 
 
=== Acids  ===
 
Some acids are used to clean surfaces, e.g. hydrochloric acid, acetic acid, formic acid and hydrofluoric acid. Accordingly, these lead to the formation of salts.
 
=== Alkaline cleaning agents ===
These include sodium and ammonium bicarbonate and Na or K lye. 
 
Carbonates may form due the application of alkaline agents. These then point to the corresponding salts. Further reactions, in the presence of [[nitrate]] and [[sulfate]], may also point to the related salts.
 
The presence of an alkali-containing building material may be concealed in the presence of "[[gypsum]]" within the pore solution, because, due to calcite precipitation, no [[natrite]] or [[thermonatrite]] efflorescence occurs, but [[thenardite]]/[[mirabilite]] efflorescence occurs instead. The simplified reaction has been approximately summarized in the following equation
 
Na<sub>2</sub>CO<sub>3</sub> + CaSO<sub>4</sub> → CaCO<sub>3</sub> ↓ + Na<sub>2</sub>SO<sub>4</sub>
 
=== Neutralization reaction ===
 
Neutralization is often carried out in the process of cleaning objects with alkaline detergents (or respectively acids). Hydrochloric acid, for example, is used for neutralizing some alkaline detergents. Apart from the fact that it is difficult to determine the success of neutralization on every part of the object, this process causes the formation of easily soluble salts, for example following this reaction:
 
NaOH + HCl → NaCl + H<sub>2</sub>O
 
== Literature  ==
 
<!--<biblist/> -->
 
[[Category:SalzHerkunft]] [[Category:Schwarz,Hans-Jürgen]] [[Category:R-HSiedel]] [[Category:R-SLaue]] [[Category:Review]]

Latest revision as of 20:23, 27 November 2012

I moved the article to the text page Hschwarz 13:31, 9 August 2012 (CEST)

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