di gregorio, s. nano restore for consolidation wall painting. 2010

8/7/2019 Di Gregorio, S. Nano Restore for Consolidation Wall Painting. 2010

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CeROArtNumro 6 (2010)Horizons

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Sara Di Gregorio

Nanorestore for the consolidation ofwall paintingsInfluence of the thermohygrometric parameters andthe presence of saline contamination on the efficacyofthe treatment

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Rfrence lectroniqueSara Di Gregorio, Nanorestore for the consolidation of wall paintings , CeROArt[En ligne], 6 | 2010, mis enligne le 17 novembre 2010. URL : http://ceroart.revues.org/index1716.htmlDOI : en cours d'attribution

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Nanorestore for the consolidation of wall paintings 2

CeROArt, 6 | 2010

Sara Di Gregorio

Nanorestore for the consolidation of wallpaintings

Influence of the thermohygrometric parameters and the presence ofsaline contamination on the efficacy of the treatment

I thank the CSGI consortium - University of Florence and in particular Dr. Piero Baglioni,

Dr. Luigi Dei, Dr. Rodorico Giorgi for making available facilities, labor and time for the

realization of this research. Dr. Andreas Kng and Dr. Cristina Mosca (SUPSI, Lugano)

for their valuable collaboration in this research and Mr. Ezio Pesenti (SUPSI, Lugano) for

constant help in the laboratory. We thank the restorer Marco Somaini (SUPSI, Lugano) and

the company Habilis Restauro s.n.c. for providing sites for case studies. We also thank Dr.

Filippo Gambinossi, Dr. Michele Baglioni, Dr. Lorenza Bernini, Dr. Marcia Carolina Arroyo

(CSGI, Florence) for assistance in the laboratory.

Introduction

1 The presence of water is one of the main causes that influence the degradation of porousstructures, such as murals, together with all the preparatory layers associated with them. Thewater has a very important role in the channeling, solubilization and crystallization of salts,because of its mobility in the porous system. The mechanisms which engage have a strongdependence on temperature and humidity conditions and are determined by phenomena ofinfiltration or capillary rise within the walls, condensation and percolation in the paint surface.

2 Nanorestore - based on the mechanisms of nanolime dispersion in isopropyl alcohol1-represents an innovative solution for the consolidation of wall paintings. The treatment canrestore some of the material lost due to degradation, replacing it with a substance identicalto the binding medium of the artifact; therefore this treatment is entirely compatible with themural paint.

3 If, for example, the wall painting has problems of decohesion and does not have sufficientresistance to withstand cleaning, the consolidating material needs to fulfill the role ofpre-consolidating. It is important to understand, therefore, whether the material used forconsolidation has good results even in a system not yet stabilized. In particular, questionscan be raised in cases of decohesion, whether the consolidating material does not exert aninhibitory effect in conditions of high salt contamination.

4 When pre-consolidation tests were performed on a study site used during the course ofMaster of Conservation and Restoration SUPSI, it was observed that in a situation of highconcentration of nitrate salts on the surface, the use of Nanorestore gave very positiveresponses. It is assumed, therefore, that the presence of hygroscopic salts could affect thekinetics of crystallization of calcium carbonate formed from hydroxide, slowing the process

of carbonation, giving the finished product the best characteristics.5 To test this hypothesis, we tried to reproduce similar situations in the laboratory, providing

a standard system to work on. Samples were made to simulate a state of crumbling paint;they were contaminated with different salt solutions and consolidated with Nanorestore .Additionally, a series of specimens were not treated in order to have materials allowing acomparison between the treated systems and the untreated samples.

6 Given the results obtained in the laboratory, we subsequently sought to verify the results onreal cases. Surface heterogeneity and the impossibility of obtaining a significant amount ofspecimen material because of the destructive nature of the sampling was probably the reasonfor not achieving comparable results in situ with proven laboratory research.


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7 The analytical phases of this study were carried out in the laboratories of the consortium CSGI2,where the product Nanorestore was developed.

8 Standard system preparation9 In order to study the influences determined by the different temperature and humidity

conditions and the presence of salts on the consolidation operated by Nanorestore, a standardmodel to work on was prepared on the base of previous experience. The system was designedwith the aim to reproduce the conditions of a mural painting that is crumbling.

10 To obtain a system of crumbling samples3

, mortars4

were prepared by increasing the volumeof aggregate5 in comparison to the usual proportions and a considerable amount of water wasadded to the mix. The layers of plaster were not compacted with manually to facilitate dryingof the mortar and ensure faster carbonation. A layer of burnt umber paint6 was applied to thedry plaster two days after application of the plaster.

11 After 45 days, a waterproof coating7 was applied on all sides of the samples , except on thepainted surface and some of the surfaces contaminated saline solutions.

12 As shown in (ill. 1), five sets of samples contaminated with salts8.13 We used salt solutions selected from those most commonly found in walls and characterized

by relative humidity values of medium-high equilibrium (75-80%): sodium nitrate and sodiumchloride. In addition to these single salt solutions, we set up a mixture of the two salts with

the addition of selected bi-hydrate calcium sulfate (gypsum), which is mainly responsible forthe degradation of salt-contaminated murals.

Fig. 1 Overview of the types of samples studied

Credits : S.di Gregorio

14 The solutions prepared for this study were:

5% solution of sodium nitrate; 5% solution of a mixture of salts consisting of one volume of the 5% sodium nitrate

solution , one volume of a 5% sodium chloride solution and one volume of a saturated

solution of bi-hydrated calcium sulphate9

; 5% solution of sodium chloride.

15 The amount of solution applied was equivalent to 5% of the total weight of the sample. In orderto ensure that the distribution of salts occurred consistently over the actual painted surfacesaffected by salt damage, we adopted the system followed by Konrad Zehnder and AndreasArnold10to study the growth of salt efflorescence in samples of mortar. In an environmentmaintained at a constant temperature of 20C, a climate chamber was constructed, in whichsamples were placed after salting. Samples were kept in the chambers for a week at aconstant relative humidity of 85%.


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16 The consolidation was performed about 100 days after the completion of the samples.Nanorestore diluted in isopropyl alcohol11 in a 1:2 ratio was applied with a brush. In total,the specimens absorbed about 3 ml of suspension, with an average weight gain of 65 grams persample. The process of carbonation of calcium hydroxide nanoparticles was followed undertwo different conditions of temperature and humidity: a series of samples was subjected to arelative humidity (RH) of 50%, and another series to a RH of 85%. Thus, the consolidationprocess took place in different conditions: those when deliquescence of hygroscopic salts

occurred and those when salts did not exhibit deliquescence. The specimens treated in thismanner were kept in constant temperature and humidity conditions for 45 days according tothe values shown in (ill. 1).

Results

17 To ensure reproducibility, three different samples from each system under consideration weresubjected to a series of laboratory tests. The following aspects were measured:

capillary rise12; vapor permeability13; contact angle14;

surface resistance to scotch tape test18 In addition the study of surface morphology of the samples by electron microscopy SEM was

conducted in order to make comparisons in behavior among different types of samples due tothe effect of surface consolidation by Nanorestore.

19 The extent of absorption of water by capillary action was performed on the same sample beforethe "salting" treatment and later, after treatment with Nanorestore. The extent of absorptionis related to capillary porosity of the material. The more porous it is, the more water it willrapidly absorb. The continued absorption in a porous system involves filling the entire systemaccording to kinetics related to the size and distribution of pores, which then influence thephenomenon. The impregnation of the porous structure by capillary pore water occurs firstin larger pores, initially as a sort of coating of the interior walls, and finally completly filling

them. The rate of absorption decreases with time and reaches an equilibrium value wherethe amount of water that impregnates the material is matched by gravity and evaporation,determining the values of capillary absorption, until achieving an asymptote value. The curvesthat are obtained in these cases have an exponential trend15. The experimental data shown inill. 2 express the amount of water absorbed by the sample before and after treatment withNanorestore and was collected until the asymptotic value was reached.


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Fig. 2 Capillary absorption curves of samples

Comparison of capillary absorption curves of samples contaminated with sodium nitrate before and after consolidation,maintained at a relative humidity of 85%.


20 The final results are expressed in terms of a capillary absorption coefficient CA16. They werederived from measurements of the curves of the development of capillary water absorptionand from values of the capillary absorption coefficient. The curves on all analyzed samples

pointed to an apparent slowing of water absorption by capillarity and a reduction in the amountof liquid absorbed by the samples after treatment with Nanorestore.


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Fig. 3 Capillary absorption curves of samples contaminated with a mixture of salts

Before and after treatment with Nanorestore , maintained at a relative humidity of 85%


21 Analyzing the trend of the curves for the different types of samples before and afterconsolidation with Nanorestore (ill. 3), it was found that the water absorbed by the specimensafter treatment was reduced by about 1-2 grams ( about 15-20% less) and that the asymptote ofthe curves was achieved about 15-20 minutes later than the curves obtained before treatment.This suggests that the surface re-cohesion happened and changed the surface porosity of thespecimens.

Fig. 4 Highlighted, average changes in the slope


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Average expressed as a percentage of the samples after Nanorestore

treatment


22 Average changes in the capillary absorption coefficient were determined from values obtainedon each specimen before and after Nanorestore treatment; a comparison with a baseline wasperformed for each investigated sample. The data obtained are represented in ill. 4; they showa greater reduction in the value of the coefficient of capillary absorption for higher values of

relative humidity because of Nanorestore treatment.23 This phenomenon is evident in all specimens except those from the gypsum polluted mixtureof salts, where ratios are reversed. It can be assumed that increasing the value of relativehumidity affects the stage of carbonation as to slow the process enough to ensure the formationof a very regular and compact crystalline structure of calcium carbonate; thereby the qualityof consolidation is improved. A greater effect should occur (according this hypothesis) onsamples contaminated by hygroscopic salts, whose deliquescence occurs in environments withrelative humidity of 85%.

24 This hypothesis seems to be confirmed by analyzing the behavior of these samples regardingthe phenomenon of capillary rise.

25 Data from samples contaminated with salt mixtures, show that Nanorestore treatmentproduced a significantly smaller effect because the change in the values of capillary absorption

coefficient before and after treatment was even lower than the salt-free sample.26 With this figure it is assumed that the cause of this phenomenon is due to the presence of

bi-hydrated calcium sulfate. Indeed, if we consider the values of solubility, we realize thatthe hydroxide and calcium sulfate have close enough values. It may be assumed thereforethat ion exchange reactions occur, and the subsequent co-precipitation removes hydroxidein the process of carbonation. That determines a much weakened re-cohesion effect. Onecan argue that consolidation with Nanorestore is not minimally affected by the presence ofsaline solutions with RH equilibriums of less than 85%. At such humidity values chloridesand nitrates deliquesce, and then the wall has a high moisture content. The bi-hydratecalcium sulfate, however, imparts a partial inhibitory effect, at least with the Nanorestoreconcentrations and quantities, which are usually used.

27 The contact angle measurement allows us to evaluate the wettability of a surface and alsoprovides guidance on specimen surface tension and capillary phenomenon dependent onsurface features. Considering the action of Nanorestore, recording data values from thisanalysis led to the search, using one of two methods that could assess changes of compactnessand regularity of the surface determined by the consolidation and, in practice, give feedbackon the recohesion of the surface material.


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Fig. 5 Highlighted, averaged contact angle of spcimens

Specimens were consolidated with Nanorestore


28 The collected data (ill.5) show some correspondence, in trend, with the results obtained instudying the kinetics of capillary absorption.

29 As evidence that the treatment affects the paint surface, the samples that were not treatedwith Nanorestore have an increased surface wettability comparing to all other tested systems(possibly because the samples have higher surface porosity). The value of the contact angle

of samples that were not treated is not so different from samples contaminated by mixtures ofsalts under conditions of 85% RH. In general, a lower wettability of the surface (and therefore abetter strengthening effect) was obtained in samples not contaminated by salts, and in sampleswith sodium nitrate, where the treatment was conducted in an environment of 85% RH.

30 Intermediate results were obtained on samples treated with Nanorestore and contaminatedby nitrate and sodium chloride, and by mixtures of salts, exposed to 50% RH. In general, thetreatment seems to have compacted the surface by reducing the surface tension, making it lesswettable as shown by the increased value of angle for almost all samples.

31 It should be noted, regarding the influence of hygrothermal factors, that an increasing value ofthe high humidity conditions (for which is assumed to obtain a better surface carbonation) wasobserved only for specimens contaminated with sodium nitrate. An opposite trend is observed

in the presence of mixtures of salts (consisting of nitrates, chlorides and sulfates).


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Fig. 6 Evolution of water loss

Vapor permeability for different types of treated samples.


32 The data derived from the vapor permeability measurements gave indications about thecharacteristics of the samples porosity. The trend of water loss through permeability wasdetermined by measurements for each studied sample. We obtained by these data a trend thatis representative of the average values of three samples for each considered type. Ill. 6 showsappreciable differences between samples consolidated in environments of 50% RH comparedto those consolidated at 85% RH. In particular, a smaller water loss by permeability in samplesconsolidated at 85% RH indicates a greater compactness.

33 These results are particularly interesting for the samples contaminated by sodium nitrate,whose consolidation showed characteristics indicating particularly low water loss because of

permeability. An exception is found for samples contaminated by sodium chloride, where thewater loss by permeability is particularly significant in relation to results obtained by othermeasurements.

34 A morphological analysis was also carried out on treated surfaces. We tried to highlightthe morphological characteristics of painted surfaces by SEM microscopy for each type ofspecimen.

35 A scanning electron microscope Stereoscan 360 (Cambridge-Oxford) was used for thispurpose. It was possible to observe the irregular surface of the non-contaminated samples anda lack of consistency of the paint layer on the microscope images (ill. 7). The grains of pigmentused in painting and fillers are visible in some areas because of the lack of binding carbonate,due to the use of lean mortar.


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Fig. 7 Scanning Electron Microscope (SEM)

Surface morphology observed at 1200 magnification. Uncontaminated sample not consolidated with Nanorestore.

Credit : S.di Gregorio


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Surface morphology observed at 1200 magnification. Uncontaminated sample consolidated with Nanorestore (50%RH)



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Surface morphology observed at 1200 magnification. Uncontaminated sample consolidated with Nanorestore (85%RH)



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Morphology of surfaces observed at 1200 magnification. Sample contaminated with sodium nitrate and consolidatedwith Nanorestore (85% RH)



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Surface morphology observed at 1200 magnification. Sample contaminated with sodium chloride and consolidatedwith Nanorestore (85% RH)



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Surface morphology observed at 1200 magnification. Sample contaminated with mixtures of salts and consolidatedwith Nanorestore (85% RH)


36 When images of uncontaminated samples are compared, we can find after consolidation (ill.8) a substantial "filling" of the gaps between the grains with a certain strengthening effectthat should be attributed to the carbonation of calcium nanoparticles on the surface .Thestrengthening effect seems to be greater in conditions of relative humidity of 85% (ill. 9); infact, the surface shows a greater continuity in the paint layer. This result was found regardlessof temperature and humidity conditions in the two samples contaminated with sodium nitrate(ill. 10). A similar result was not observed on the samples previously contaminated by sodiumchloride (ill. 11). The effect is even less evident for the samples "salted" by mixtures (ill. 12)containing sulfate salts.

37 Comparing all the images, we can state that, in general, the values of relative humidity of 85%(being kept constant during the process of the Nanorestore reaction) lead to carbonation ofnanoparticles, which produces a more compact layer of paint because of the neoformation of

calcium carbonate.38 The results of adhesion tests performed by the Scotch tape test did not permit to characterise the

treatment regarding the cohesion of the paint film. This is due to the fact that such specimenswere not suitable for sensitivity testing.

The case of bi-hydrated calcium sulfate

39 The work showed some problems about the effectiveness of Nanorestore consolidation insamples contaminated by a mixture of salts. An investigation was performed, testing whetherthe inhibitory effect on consolidation was due to the presence of calcium sulfate. In particular,


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it was conjectured that the value of solubility of calcium sulfate, very close to that of calciumhydroxide, might lead to an exchange reaction between the salt and the Nanorestore product.

40 It was decided for that purpose to select 6 samples among those already prepared in thelaboratory with a 5% weight of salt in the sample. They were contaminated by a saturatedsolution of calcium sulfate and were consolidated with a dispersion17 of Nanorestore that wasdiluted in isopropyl alcohol18 and mixed with a dispersion of strontium nanoparticles19. Thesenanoparticles are engaged in an exchange reaction with calcium sulfate, thereby permitting

calcium nanoparticles to lead to consolidation without any other interference.41 After consolidation, the specimens were kept in an environment of 85% RH and 20 C for

about 45 days.42 The samples have been studied at the end of the consolidation process by analyzing capillary

absorption, measurement of the angle contact and vapor permeability. The results actuallyshow a positive response to the consolidation with Nanorestore, due to the action ofstrontium nanoparticles on the exchange reaction with the bi-hydrate calcium sulfate.

43 If the obtained values are compared with those of previously analyzed samples, one mayhighlight a response to consolidation similar to that found on the untreated samples, alwaysconsidering the margin of experimental error. One can then associate such a result to what hasbeen achieved in a situation that is not influenced by salts.

Conclusions

44 The research shows that the influence of salts in porous materials results in some inhibitionin the consolidation process with the exception of hygroscopic salts, when the consolidationtakes place in a high relative humidity. Some doubts exist regarding the behaviour of sodiumchloride, due to discrepancies between the results of different analysis. This positive behaviorof salts on consolidation can be explained by the fact that, under conditions of high relativehumidity, the hygroscopic salts that contaminate specimens deliquesce, subsequently causinga high moisture content not only on the surface (as in the untreated samples) but in the internalsystem. One can speculate whether this affects the stage of carbonation to the extent thatthe process turns to be slow enough to ensure the formation of a very regular and compact

crystalline structure of calcium carbonate, thereby improving the quality of consolidation. Thisprocess would lead to benefits that would counterbalance problems related to the presence ofsalts as well as, in some cases, it would probably provide an advantage in the kinetic processof consolidation.

45 The problems affecting the effectiveness of consolidation, resulting from the presence ofmixtures of salts, have to be attributed to bi-hydrate calcium sulfate salt. The solubility valuesfor calcium hydroxide and calcium sulfate are so close20that one can assume ion exchangereactions take place as well as subsequent co-precipitation, which would remove the calciumhydroxide from the process of carbonation.

46 A solution to this problem was given by the use of alcoholic dispersions of strontiumhydroxide. This, being more reactive to the bi-hydrate calcium sulfate than the calcium

hydroxide, allows Nanorestore to perform consolidation without the process being affectedby plaster.

47 These data show that Nanorestore treatment on murals that are affected by the presenceof hygroscopic salts has no contraindications in conditions when relative humidity is above85%. The water that is absorbed by condensation of the salt species seems to have a positiveinfluence on the process of carbonation of the involved particles. In the case of plaster, theproduct Nanorestore shows a lower efficiency, and then a more consistent application interms of quantity of material or of a support of alcoholic dispersion of strontium hydroxideis necessary.


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Bibliographie

AMBROSI, M., DEI, L., GIORGI, R., NETO, C., BAGLIONI, P. (2001). Colloidal particles of Ca(OH)2: propertiesand application to restoration of frescoes , in Langmuir17, p.4251-4255.

ARNOLD, A., ZEHNDER, K. (1991). Monitoring Wall Paintings Affected by Soluble Salts in Theconservation of wall paintings. Proceedings of the symposium organized by the Courtauld Institute ofArt and the Getty Conservation Institute, London, July 13-16, 1987. Los Angeles, Sharon Cather Editor,p.103-135.

ARNOLD, A., ZEHNDER, K. (1989). Crystal growth in salt efflorescence , in Journal of Crystal Growthn 97, p.513-521.

BAGLIONI, P., VARGAS, R. C., CHELAZZI, D., COLN, G. M., DESPRAT, A., GIORGI, R. (2006). The Maya site ofCalakmul: in situ preservation of wall paintings and limestone using nanotechnology in Proceedingsof the IIC Congress The Object in Context: Crossing Conservation Boundaries, Munich, Edited byDavid Saunders, Joyce H. Townsend and Sally Woodcock, p.162-169.

BAGLIONI, P., GIORGI, R., (2006) Soft and Hard nanomaterials for restoration and conservation ofcultural hritage , in Soft Matter, A92, p. 293-303.

CILIBERTO, E., CONDORELLI, G. G., LA DELFA, S., VISCUSO E. (2008). Nanoparticles of Sr(OH)2: synthesisin homogeneous phase at low temperature and application for cultural heritage artefacts . in AppliedPhysics, p.137-141.

CROVERI, P., L. DEI, CASSAR, J. (2007). Metodologie di consolidamento di superfici architettonicheinteressate da Sali solubili. Il caso di studio delle fortificazioni maltesi: valutazione dellefficacia deitrattamenti e criticit in Il consolidamento degli apparati architettonici e decorativi. Bressanone,Arcadia Ricerche, p.539-549.

DEI, L., SALVADORI, B. (2006). Nanotechnology in cultural heritage conservation: nanometric slakedlime saves architectonic and artistic surfaces from decay , in Journal of Cultural Heritage, n 7,p.110-115.

GAETANI, M. C., SANTAMARIA, U. (2007) Studio sperimentale per la valutazione di prodotti protettiviapplicati in situ e definizioni di una metodologia, In Facciate dipinte. Verifiche sui protettivi emetodologie innovative di pulitura a Feltre e nel Veneto orientale. Saonara (Padova), Il prato, p.15-30.

Notes1 Nanorestore is a registered trademark CSGI protecting the technology developed there and protectedby the Italian Patent No. FI/96/A/000255, filed on 31/10/1996 by CSGI Consortium - University ofFlorence.

2 Piero Baglioni, Luigi Dei, Rodorico Giorni Consorzio CSGI-Dipartimento di Chimica, Universitdegli Studi di Firenze, Via della Lastruccia 3-13, 50019, Sesto Fiorentino.

3 Samples : dimensions 5cm x 5cm x 2cm, 0.5cm thick plaster and 1.5cm arriccio.

4 Slaked lime Candor Company Adriatic Timbers Ltd - S.S.16 Fasano Brindisi (BR) - Italy.

5 Geniobeton SA - 6532 Castione - Canton Ticino Switzerland

6 Bresciani S.r.l. via Breda 142 20126 Milano Italy

7 Type road marking paint Strassensignierfarbe RUCO Company Rupf Eichstr & Co AG. 42-8152Glattbrugg - Canton Zurich - Switzerland.

8 VWR International AG - Lerzenstrasse 16/18 - 8953 Dietikon Canton Zurich Switzerland.

9 2g/l

10 Arnold Andreas, Zehnder Konrad, Crystal growth in salt efflorescence, Journal of Crystal Growth,1989, 97, 513-521.

11 CTS S.r.l. Via Piave 20/22 - 36077 Altavilla Vicentina Vicenza - Italy.

12 UNI EN 15801 :2010, Commissione Beni Culturali-Normal, UNI, Milano 2009.




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15 The trend is described by an exponential equation y = a [1 - exp (-b t)], where the term 'a' isthe maximum amount of liquid that is absorbed by capillary action, it is expressed in kg/m2(contactsurface) ; while 'b', expressed in units t-1/2, is a factor that considers the suction speed and the porevolume filling, it corresponds to the coefficient of water related to height slope.

16 AC = A/ t*1/2, and expressed in g/(cm2 s1/2), where A indicates the asymptotic value of wateramount absorbed by the sample, t* is the value in the abscissa of the intersection point between the linethrough the asymptote and the tangent to the straight section of the curve (s1/2).

17 Nanorestore : 2 parts by volume, suspension of nanoparticles of Strontium : 1 part by volume,

isopropyl alcohol, 6 parts by volume.18 CTS S.r.l. Via Piave 20/22 - 36077 Altavilla Vicentina Vicenza

19 Concentration 8gr /l

20 Solubility in water at 20 C : Ca(OH)2 = 1,7 g /l CaSO4.2H2O = 2,4 g /l

Pour citer cet article

Rfrence lectroniqueSara Di Gregorio, Nanorestore for the consolidation of wall paintings , CeROArt[Enligne], 6 | 2010, mis en ligne le 17 novembre 2010. URL : http://ceroart.revues.org/index1716.html

Sara Di Gregorio

Sara Di Gregorio (1979) performed art studies and graduates at Florence International Universityof Art, on frescos restoration. She started working in the field and she engaged in a work at theOpificio delle Pietre Dure (Florence). In 2008 she enrolled at the Master of Arts in Conservation andRestoration at SUPSI.

Droits d'auteur

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Rsum / Abstract

Cet article prsente les rsultats dun projet de recherches sur leffet de lapplication du produitNanorestore, dispersion de nanoparticules de chaux dans lalcool isopropylique, pour laconsolidation des peintures murales ; il value linfluence des conditions environnementalesexternes (UR et prsence des sels en particulier) sur le processus de carbonatation.Mots cls : consolidation,Nanorestore,nanoparticules,sels,peintures murales

This paper presents the results of an investigation project on the use of Nanorestore, adispersion of nanolime in isopropyl alcohol, used for the consolidation of wall paintings. The

influence of environmental conditions outside the wall (high humidity environments and highpresence of hygroscopic salts) on carbonation process was considered.Keywords : consolidation,salts,wall paintings,nanoparticles,Nanorestore

ndlr : Scuola Universitaria Professionale della Svizzera Italiana - CSGI ConsorzioInteruniversitario per lo Sviluppo dei Sistemi e Grande Interfase dell'Universit di Firenze Contact : Giacinta Jean

di gregorio, s. nano restore for consolidation wall painting. 2010

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