EN 17891:2023
(Main)Conservation of cultural heritage - Desalination of porous inorganic materials by poultices
Conservation of cultural heritage - Desalination of porous inorganic materials by poultices
This document specifies a methodology applying poultices for the desalination of porous substrate constituting cultural heritage. The desalination methodology can be applied:
- to salt-loaded porous inorganic materials affected by salt weathering, and/or
- to allow conservation treatments incompatible with soluble salt(s) contamination, or
- to prevent salt damage where contamination is known to be present.
In all cases the desalination aims to decrease the salt content.
Furthermore, this document gives the fundamental requirements for the desalination operation and guidelines for the choice of the most appropriate poultice components according to the characteristics of the substrate and types/quantities of salt(s) present in order to optimize the desalination process.
Erhaltung des kulturellen Erbes - Entsalzung poröser anorganischer Materialien durch den Einsatz von Kompressen
Dieses Dokument legt eine Methodik für den Einsatz von Kompressen zur Entsalzung poröser Untergründe, die kulturelles Erbe darstellen, fest. Die Methodik der Entsalzung kann angewendet werden:
- bei salzbelasteten porösen anorganischen Materialien, die von Salzverwitterung betroffen sind, und/oder
- um Konservierungsbehandlungen zu ermöglichen, die mit einer Verunreinigung durch lösliches Salz/lösliche Salze unverträglich sind, oder
- um bei bekannter Verunreinigung Salzschäden zu verhindern.
In allen Fällen ist das Ziel der Entsalzung die Verringerung des Salzgehalts.
Darüber hinaus enthält dieses Dokument die grundlegenden Anforderungen an den Entsalzungsvorgang sowie Leitlinien für die Wahl der am besten geeigneten Kompressenbestandteile entsprechend den Eigenschaften des Untergrunds und den Arten/Mengen des/der vorhandenen Salze(s), um den Entsalzungsprozess zu optimieren.
Conservation du patrimoine culturel - Dessalement des matériaux inorganiques poreux par application de compresses
Le présent document spécifie une méthode de dessalement par application de compresses sur des matériaux inorganiques poreux constituant un patrimoine culturel. La méthodologie de dessalement peut être appliquée :
- aux matériaux inorganiques poreux chargés en sel affectés par l'altération par les sels ; et/ou
- pour permettre des traitements de conservation incompatibles avec la contamination par le(s) sel(s) soluble(s) ; ou
- pour éviter les dommages causés par les sels lorsque la contamination est connue.
Dans tous les cas, le dessalement a pour objectif de diminuer la teneur en sel.
De plus, le présent document fournit les exigences fondamentales pour l'opération de dessalement et les lignes directrices pour le choix des composants de compresse les plus appropriés selon les caractéristiques du substrat et les types/quantités de sel(s) présent(s) afin d'optimiser le processus de dessalement.
Ohranjanje kulturne dediščine - Razsoljevanje poroznih anorganskih materialov z oblogami
Ta dokument določa metodo za razsoljevanje poroznih anorganskih materialov z oblogami, ki predstavljajo kulturno dediščino. Metodologijo razsoljevanja je mogoče uporabiti za porozne anorganske materiale z visoko vsebnostjo soli, ki zaradi tega preperevajo, in/ali da se omogoči konzervativno obdelovanje, ki je nezdružljivo s kontaminacijo s topno soljo, ali za preprečevanje poškodb zaradi soli, kjer je kontaminacija ugotovljena. V vseh primerih je cilj razsoljevanja zmanjšati vsebnost soli.
Dokument prav tako podaja temeljne zahteve za postopek razsoljevanja in smernice za izbiro najprimernejših sestavnih delov oblog v skladu z značilnostmi podlage in vrstami/količinami prisotne soli za optimiziranje postopka razsoljevanja.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2023
Ohranjanje kulturne dediščine - Razsoljevanje poroznih anorganskih materialov z
oblogami
Conservation of cultural heritage - Desalination of porous inorganic materials by
poultices
Erhaltung des kulturellen Erbes - Entsalzung poröser anorganischer Materialien durch
den Einsatz von Kompressen
Conservation du patrimoine culturel - Dessalement des matériaux inorganiques poreux
par application de compresses
Ta slovenski standard je istoveten z: EN 17891:2023
ICS:
71.060.01 Anorganske kemikalije na Inorganic chemicals in
splošno general
97.195 Umetniški in obrtniški izdelki. Items of art and handicrafts.
Kulturne dobrine in kulturna Cultural property and
dediščina heritage
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN 17891
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2023
EUROPÄISCHE NORM
ICS 71.060.01; 97.195
English Version
Conservation of cultural heritage - Desalination of porous
inorganic materials by poultices
Conservation du patrimoine culturel - Dessalement des Erhaltung des kulturellen Erbes - Entsalzung poröser
matériaux inorganiques poreux par application de anorganischer Materialien durch den Einsatz von
compresses Kompressen
This European Standard was approved by CEN on 23 July 2023.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17891:2023 E
worldwide for CEN national Members.
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Symbols and abbreviations . 9
5 Principles of poultices desalination . 9
5.1 General. 9
5.2 Advection-based poulticing methods . 10
5.3 Diffusion-based poulticing methods . 10
6 Test equipment . 11
7 Methodology for the determination of the operational parameters . 11
7.1 General. 11
7.2 Selection of the poultice/s component/s . 11
7.3 Poultice formulation and required properties . 12
7.4 Poultice preparation by water addition . 12
7.5 Trial evaluation of harmfulness and effectiveness . 13
7.5.1 General. 13
7.5.2 Measuring the amount of ions transferred from the substrate to the poultices . 13
7.5.3 Measuring the ion content in the substrate before and after desalination . 14
8 Desalination process . 14
8.1 Environmental conditions of application . 14
8.2 Preparation of the substrate . 14
8.3 Poultice application . 14
8.3.1 General. 14
8.3.2 Thickness of poultice . 15
8.3.3 Time of application . 15
8.3.4 Removal of the poultice . 15
8.4 Number of applications . 15
9 Test report . 16
Annex A (informative) Desalination poultices . 17
A.1 Clay materials . 17
A.2 Cellulosic and wooden materials . 17
A.3 Gelling materials aqueous, non-aqueous, and mixed gels . 17
Annex B (informative) Advection and diffusion process . 19
B.1 Advection . 19
B.2 Diffusion . 20
Annex C (informative) Workability and consistency: flow test (EN 459-2) Cone penetration
(EN 413-2) of poultices . 21
Annex D (informative) Identification of salt species or ions according to EN 16455 . 22
Annex E (informative) Number of applications . 23
E.1 General . 23
E.2 Trial test removing ions from a brick wall masonry . 23
E.3 Trial test: case study on a mural painting surface . 24
Bibliography . 26
European foreword
This document (EN 17891:2023) has been prepared by Technical Committee CEN/TC 346 “Conservation
of Cultural Heritage”, the secretariat of which is held by UNI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2024, and conflicting national standards shall be
withdrawn at the latest by April 2024.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United
Kingdom.
Introduction
Salts are often present in stones and other porous substrates as agents of decay of chemical, biological or
anthropogenic origin. They can originate from surface deposition of atmospheric pollutants, from
capillary transport or from external sources such as wind driven marine aerosol and from the material
itself, and may be present due to previous, unsuitable, restoration interventions.
The salts most often encountered in building materials are sulfates, chlorides, nitrates and carbonates of-
sodium, potassium, ammonium, calcium and magnesium. Frequently present are the sulfates: gypsum
(CaSO ·2H O), mirabilite (Na SO ·10H O) and thenardite (Na SO ), epsomite (MgSO ·7H O) and other
4 2 2 4 2 2 4 4 2
hydrates, the chlorides halite (NaCl) and sylvite (KCl), the nitrates niter (KNO ) and nitratine (NaNO ).
3 3
and the carbonates thermonatrite (Na CO ·H O), trona (Na H(CO ) ·2H O. Less frequently double salts
2 3 2 3 3 2 2
can be observed e.g. aphthitalite (K Na (SO ) ), carnallite (KMgCl ·6H O). Minor occurrence of
3 4 2 3 2
phosphates and nitrites can be found.
In general, several types of soluble salts coexist and the ionic species present, depending on the
conditions, can interact with each other to form complex salts or lead to crystallization phenomena within
and/or on the surface of the object.
The solubility of any individual salt within a given system varies greatly and is influenced by the
concentration and type of other salts in the system and on the temperature. Generally, the concentration
of soluble salts in the substrate is highest near the surface, though increased salt contents can occur inside
to considerable depths.
Salts can damage the fabric of porous inorganic materials and lead to different decay morphologies
sometimes causing substantial loss of material from the object. In addition, water-soluble salts have an
influence on conservation measures such as cleaning, consolidation, treatment with hydrophobic
materials and painting or plastering, often hindering them. The extent of deterioration and its appearance
depend, for a given material, on the type of salt(s) crystallizing, the amount of salt(s) present, and the
environmental conditions, as well as the presence of moisture, leading to crystallization cycles.
Reduction of the salt content (desalination) is an essential prerequisite for reducing the deterioration
rate of the object and for the success and durability of a conservation measures. However, it is also
recognized that in some systems desalination may at best be only partially successful.
Desalination by poultices is one of the most common methods used to reduce salt content from objects.
The term desalination is used to indicate a reduction in the ion content of water-soluble salts,
preferentially in the near surface layers of the substrate, rather than a removal of all salts from the
substrate at depth.
Before any intervention/application to reduce salts and their ensuing damage, it is advisable to consider
investigation and relevant interventions to prevent excessive moisture penetration as part of a holistic
conservation approach.
Desalination is a decision that should be taken only after having carried out exhaustive investigations
which take into account all the aspects related to damage by salts, such as the type of salts present, their
origin, their amount and distribution, as well as the surrounding environmental conditions. In
...
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