Tailoring new fluorinated acrylic copolymers as protective coatings for marble

The protective performances of two new fluorinated acrylic copolymers (based on the monomers 1H,1H,2H,2H-perfluorodecyl methacrylate (XFDM) and 1,1,1,3,3,3-hexafluoroisopropyl methacrylate (HFIM) are evaluated and compared with Paraloid B72, a commercial copolymer ethyl methacrylate/methyl acrylate (EM/MA) and its partially fluorinated homologous 2,2,2-trifluoroethyl methacrylate/MA (TFEM/MA). The polymeric materials have been tested on Candoglia marble, a very low open porosity stone (<1%) used in Italian historical architecture (Milan Cathedral). The copolymers were tested according to UNI-Normal protocol. Measurements of capillary water absorption, static contact angles, colour variation and water vapour permeability were made before and after accelerated photo-ageing. FTIR spectroscopy and size exclusion chromatography (SEC) analyses were carried out on samples aged on inert substrate to assess the photostability of the copolymers themselves. The relationship between the protection efficacy and the fluorine content and distribution has been investigated. The results obtained show that the addition of a partially fluorinated co-monomer to the Paraloid B72 copolymer structure did not result in the expected improvement of the coating properties, while the fluorination of the copolymer side chain gave rise to encouraging performance.     

Research on protection of the architectural glazed ceramics in the Palace Museum,Beijing

The main damage of architectural glazed ceramics in the Palace Museum was investigated and the photo resistance, thermal resistance of protective materials as well as the protected performance such as hydrophobicity, freeze-thaw resistance, bending and compressive strength of the polymer-applied ceramics was tested. The results showed the main damage of glazed ceramics was the shedding of glaze layer and the change of environmental water and temperature especially subzero was the main reason for the glaze shedding. The photo-resistant and thermal-resistant of protective materials fluorine resin and the compound materials composed mainly of the fluorine resin were better than Paraloid B72 and the compound materials composed mainly of Paraloid B72. The wrapping method was selected for the protection of glazed ceramics and the hydrophobicity, freeze-thaw resistance, bending and compressive strength of the polymer-applied ceramics were improved, especially protected by fluorine resin and the compound materials composed mainly of the fluorine resin. The optimum polymer could penetrate into the damaged seriously glazed ceramics and play a hydrophobic role in the protection. The report will be useful for the preservation of damaged seriously architectural glazed ceramics.     

Consolidating properties of Regalrez 1126 and Paraloid B72 applied to wood

This study is aimed at an assessment of the properties of two polymeric products applied to Norway spruce (Picea abies) and White poplar (Populus alba) wood species. It contributes to ongoing research experiments on the consolidating properties of two synthetic resins and their potential synergic action on wood, resulting from their different interaction with the substrate: Paraloid B72 and Regalrez 1126. Experiments were carried out on a series of samples of the two wood varieties. The consolidants were applied alone and one after the other, with one coat of Regalrez and then one of Paraloid. Porosity and variations in pore size distribution were ascertained by mercury intrusion porosimetry (MIP). Colorimetric and IR spectroscopic measurements were also taken before and after aging by solar radiation and freeze/thaw cycles, to verify the possible slowing of photodegradation of the treated wood and the consolidating resistance. Results confirm that both products penetrate the wood with a different behaviour. After double treatment with Regalrez + Paraloid, a significant advantage was observed in terms of mechanical resistance and pore size distribution, although no advantages as regards resistance to photo-oxidizing processes or colour changes were observed.     

Evaluation of the effectiveness of treatment products in improving the quality of ceramics used in new and historical buildings

Ceramic samples made with a mixture of 70% ball clay and 30% quartz sand were moulded and then fired at 900 °C in an electric kiln. Samples were then treated with different products and analyses and tests were performed to evaluate the physical changes induced by the application of these products and their effects on the quality of the ceramics. A petrographic study indicated that the ceramics were composed of quartz, small amounts of mullite and sanidine and traces of hematite. Mineral clays (i.e. kaolinite) disappeared during firing. Two consolidating products (Paraloid B72 and Tegovakon V) and one water repellent (Silo 111) were applied to samples by capillarity, and physical changes (colour, water flow, porosity and pore size distribution) were measured. Finally, we carried out salt crystallization tests in order to determine which product improved the quality of the ceramics. Treated samples registered a decrease in porosity and a general increase in pore size. The application of Silo 111 drastically reduced water absorption by immersion and by capillarity. This product was also responsible for a decrease in pore interconnection. Samples treated with Tegovakon V performed better in terms of their overall hydric behaviour. Silo 111 was the only product that did not modify the colour of samples when compared with untreated ones, and after accelerated aging tests, samples treated with this product hindered the absorption of saline solution into ceramic pores and prevented their decay. Paraloid B72 did not improve any of the properties of the ceramics.     

Consolidation of paint on stained glass windows: Comparative study and new approaches

Stained glass windows belong to the most precious pieces of art in many European countries. Examples of heavily endangered paint on glass are reported in the literature and mainly related to condensation effects and air pollution, as stained glass windows preferably remain in their original architectural surrounding. Several surface coatings and paint treatments have been proposed to consolidate and protect degraded paint. Very often, the selection of the materials is based more on practical aspects than on scientific research. This study concerns the comparison of some traditional, modern and newly developed consolidants for the preservation of historic glass paintings. Experiments have been carried out with model painted glass samples simulating weathering phenomena of originals. Traditional materials like Paraloid B72, modern ones like SZA (proposed by the Fraunhofer-Institut für Silicatforschung, ISC), and three new consolidants prepared by the sol–gel method and based on different hybrid organic–inorganic alkyl-alkoxysilane systems have been considered. The adhesion, penetration, stability, hydrophobicity, mechanical and chemical resistance are properties and requirements tested to prove their effectiveness and range of use. The three new materials developed in this study for the consolidation of paint on glass have the potential to offer alternatives to existing materials. Nevertheless, further research is necessary before their application in restoration workshops can be recommended. A strategic approach is requested to avoid risks for these valuable historical originals and to contribute to the long-term preservation of the paint on stained glass windows in their original sites.     

Examination,conservation and analysis of a gilded Egyptian bronze Osiris

A heavily corroded Egyptian bronze figurine of the god Osiris was examined and shown to have been originally gilt with gold leaf and inlaid with blue glass. Detailed formal comparison between this Osiris figure and the known corpus of bronze and stone sculpture leads to the inference that the statuette dates to the time between the Third Intermediate Period and the fourth century BC, with a greater probability of originating from the Third Intermediate Period through to the 26th Dynasty, or even possibly as late as the fourth century on the basis of stylistic similarities. An extensive corrosion crust of atacamite and chalconatronite completely obscures inlaid glass decoration, found during the investigation, together with remnants of a gilded surface. Analysis of the glass by electron microprobe showed a composition consistent with early Egyptian blue glass with high sodium oxide and low potassium oxide content. The solid cast bronze is a leaded tin bronze, and the gold is a gold foil applied to the bronze surface, originally alternating in decoration with the blue glass. The chalconatronite and atacamite patina appear to be closely associated in the development of the unusual but extensive chalconatronite crust that now covers part of the surface, as a natural corrosion process in this case, not derived from subsequent conservation treatment. The loss of the light blue corrosion crust was prevented by consolidation with Paraloid B72, as examination over several months showed no sign of continued chemical instability.     

Methyl–modified hybrid organic-inorganic coatings for the conservation of copper

A simple sol-gel technique for the preparation of methyl–modified silica coatings for the protection of the external surface of copper has been used in this study. Tetraethylorthosilicate (TEOS) has been used as a precursor to prepare nanosilica coatings on the surface of copper. The methyl–modified silica sols were obtained by mixing of 3% SiO₂ sol solution with trimethylchlorosilane (TMCS) or hexamethyldisilozane (HMDS) as basic materials. For comparison, the copper substrates were also coated with commercial polymers (Paraloid B 72, Plexisol P 550-40 and polyvinyl butyral (PVB)). The surface morphology changes of uncoated and coated specimens were investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The hydrophobicity of surfaces and photochemical ageing effects were evaluated by contact angle measurements. Potentiodynamic measurements were obtained in order to compare corrosion parameters of the coatings.     

The funerary klinai of tomb 1 from Amphipolis and a sarcophagus from ancient Tragilos, eastern Macedonia: a physico-chemical investigation on the painting materials

Optical and SEM-EDS microscopy, X-ray powder diffraction and micro FT-IR spectroscopy investigations of the funerary klinai (couches) of Tomb 1 from Amphipolis and a stone sarcophagus from ancient Tragilos—two painted monuments made by Macedonian craftsmen of the Early Hellenistic period—identified the original materials and painting technique, as well as synthetic materials used as consolidants during past restoration treatments. The original organic binders and the superficial modern coatings have been identified by micro FT-IR spectroscopy applied directly to the sampled powders or tiny fragments and to their solvent—soluble fractions. The pigments identified on the couch of Amphipolis are: red and yellow ochre, cinnabar, Madder lake, paratacamite and antlerite, carbon black, calcium carbonate, kaolin and gypsum. The identification of egg and animal glue confirms the application of tempera and secco techniques. The detection of polymers such as polydimethylsiloxane, polyvinyl acetate and alkyd resins, is related to modern restoration products. The pigments attested on the paintings of the Tragilos' sarcophagus are: red and yellow ochre, Egyptian blue, malachite, carbon black, calcium carbonate and gypsum. The absence of organic binders combined with the constant presence of calcium carbonate in all the examined samples suggests the use of lime as the binding medium in the painted decoration of the sarcophagus. The presence of Paraloid B72 is related to recent conservation treatments.     

Use of Spanish broom (Spartium junceum L.) canvas as a painting support: Evaluation of the effects of environmental conditions

One of the problems in the field of cultural heritage is the degradation of artworks and especially paintings. They appear very sensitive to environmental conditions. In this work, Spanish broom canvas is proposed as a novel painting support. In order to assess the deterioration properties of this new type of canvas, three degradation processes (exposure to wet atmosphere, to acidic attack and to UV light) were simulated and investigated. The deterioration state of the samples was monitored with Infrared Spectroscopy (FT-IR) and Thermogravimetric Analysis (TGA). The structure of the canvas was also analyzed by Scanning Electron Microscopy (SEM). These techniques were successfully applied to study the occurrence significant changes of samples. The exposure to acidic and UV attack produced deep changes on the samples (only on the canvas surface in the case of UV light), while no significant effect was identified on the sample after the exposure to wet atmosphere. The results obtained from Spanish broom canvas are reported in comparison to flax canvas.     

Testing a fluorinated compound as a protective material for calcarenite

A polyfluorinated compound was studied as a material for the specific protection of calcarenite. Water capillary absorption and vapour permeability measurements were carried out in order to evaluate efficiency as a protective agent. Particular attention was given to characterising its resistance against bio-deterioration induced by microorganisms such as blue and green algae. Chemical surface modifications were induced by UV-irradiation in a specially designed climatic chamber and were investigated through comparative tests on untreated and artificially weathered samples using X-ray photoelectron spectroscopy (XPS). This paper discusses the potential use of the compound studied as a specific coating material for the protection of calcarenite.     

Halite – A new calibration material for microdrilling resistance measurements

This paper aims at proposing a new calibration material for microdrilling resistance measurements. Microdrilling resistance is a microdestructive method mainly used in built heritage in order to determine the strength profile in depth. This method is suitable to detect changes in the material cohesion, either due to a different state of preservation or to the action of a consolidant. Calibration materials are often used in microdrilling measurements in order to characterise the drill bit initial value and to correct the variations existing within the initial values of a set of drill bits. Calibration materials are also useful to detect the wear effect on a drill bit due to an abrasive stone. Moreover, such materials can be used for comparing results obtained with different microdrilling machines. In this work, halite was chosen to be tested as a calibration material due to its properties, as low hardness and isotropy. Halite single crystals and halite salt stone from different provenances were tested in order to evaluate the suitability of this material to the requests of a calibration material for microdrilling resistance applications, as for instance being homogeneous, non-abrasive, sensitive and available worldwide. Experimental results show that halite from different provenances is very homogeneous, especially in the crystalline form. This form of halite is slightly more expensive than stone halite; however its costs are comparable to ARS and significantly lower than Macor (other calibration materials commonly used for microdrilling resistance measurements). Due to the advantages of halite for calibration purposes, this material should be further tested by other authors in order to validate our conclusions.     

A visible and long-wavelength photocured epoxy coating for stone protection

An epoxy coating modified by PDMS hydroxyl terminated is presented in this paper in order to evaluate its potential use as a protective of a stone surface. With a view to its use in restoration sites, visible and long-wavelength photoinitiated cationic polymerization is proposed here. The system investigated is based on a crosslinking mechanism which shows remarkable advantages for stone protection, such as the low toxicity of the products and facility of mixture preparation. Furthermore, the visible light exploitation represents the most important advantage, because it is easy to apply in a restoration site, with or without irradiation instruments. Besides coating characterization through FT-IR, DMTA analyses and contact angle measurement on glass slides, analyses were also carried out on coated plaster samples. These analyses were performed in order to evaluate the effectiveness of the protective, in relationship to hydrophobicity (contact angle measurement, capillary water absorption) and morphology surface changing (SE/SEM observations, colorimetric measurements) before and after polymer application and UV aging test of coated samples. The overall characterization makes it possible to consider it a suitable coating for stone protection.     

Assessment of synthetic polymeric coatings for the protection and preservation of stone monuments

The performance of five synthetic coatings for the protection of stone monuments of Hellenistic and Byzantine period has been evaluated. The selected coatings included four commercially available siloxane-, siloxane/acrylic- and perfluoroether-based compositions, as well as a new composition based on newly synthesized fluoro-organosilane. The coatings were applied onto petrologically different stone substrates, such as marble, travertine, sandstone and a newly baked brick compatible with Roman period bricks, used for the restoration processes in Galerius Palace, Thessaloniki, Greece. The coatings' protective efficiency was investigated by measurement of water–stone contact angles, water vapor permeability, and water absorption by capillarity. The optical properties of the applied coatings were also investigated and they were also ranked with regard to their optical characteristics.     

Positive findings for plasma polymer (meth)acrylate thin films in heritage protective applications

Plasma technology is an innovative environmental friendly process that can be an option to the conventional methods for materials’ processing. Nonequilibrium low pressure plasma found efficiency as a nondestructive method for the treatment of different materials, many of them belonging to the cultural heritage, in some proper operations such as: atomic-level cleaning, decontamination, thin film deposition. In the paper, the low pressure nonequilibrium plasma is applied for the deposition of plasma polymer poly(methyl methacrylate-co-ethyl acrylate) P(MMA-co-EtA) thin films on natural aged paper, with the consolidation and protective aim. To verify the plasma polymer applicability for paper protection and consolidation, the film is aged accelerated by UV radiation and the structural and morphological changes are evaluated by FTIR spectroscopy, color/gloss measurement, contact angle and AFM.     

Self-cleaning materials on Architectural Heritage: Compatibility of photo-induced hydrophilicity of TiO2 coatings on stone surfaces

Titanium dioxide (TiO₂) can be used to realize transparent self-cleaning coatings on stone surfaces as an active and preventive protection system, limiting cleaning and maintenance actions, reducing their costs in Architectural Heritage. This self-cleaning ability is due to photo-induced hydrophilicity on treated surfaces. The aim of this investigation is to analyze this effect, since it could bring to a greater water absorption, a potential source of damage for stone surfaces. Titania sol, obtained by sol-gel and hydrothermal processes, was deposited on travertine by spray coating, in two different ways. Water absorption by capillarity, static contact angle and a specific surface water absorption analysis were assessed before and after the TiO₂ treatments. The effects of deposited amount of titania on the characteristics of treated surfaces were evaluated. It was shown that there were no evident changes in the substrate reactivity without ultraviolet (UV) light exposure, while it seems that hydrophilicity due to UV light does not lead to higher water absorption, thus encouraging the use of TiO₂ coatings in the field of Architectural Heritage. However, before widely applying this conservative treatment, some further researches are recommended in order to better assess its durability and sustainability.     

In situ copolymerisation of ethylmethacrylate and methylacrylate for the restoration of stone artefacts

In this paper the consolidating and protective products used in the restoration of stone manufactured objects of artistic interest are discussed; advantages of the different products and the relevant properties of the polymeric materials are underlined. The penetration of polymeric consolidating materials is very small and the in situ polymerisation of the monomers is suggested as an alternative technique to using macromolecular solutions. Some experimental results are presented showing that the in situ polymerisation improves the consolidating and the protective properties of polymers.     

Representing and Performing Businesses

This article investigates a segmentation model used by the Danish Tax and Customs Administration to classify businesses' motivational postures. The article uses two different conceptualisations of performativity to analyse what the model's segmentations do: Hacking's notion of making up people and MacKenzie's idea of performativity. Based on these two approaches, the article demonstrates that the segmentation model represents and performs the businesses as it makes up certain new ways to be a business and as the businesses can be seen as moving targets. Inspired by MacKenzie the argument is that the segmentation model embodies cleverness in that it simultaneously alters what it represents and then represents this altered reality to confirm the accuracy of its own model of the businesses' postures. Despite the cleverness of the model, it also has a blind spot. The model assumes a world wherein everything around it is in motion and can be shaped, however, it sees itself as stable. This assumption turns out to be problematic as the tax administration questions the model's ability to produce valid comparisons. The article presents a detailed analysis of the model's performativity, providing an example of a performativity study whose methodology differs from the methodological criteria set up by MacKenzie.     

Effects of silica nanoparticle and GPTMS addition on TEOS-based stone consolidants

Consolidants based on tetraethoxysilane (TEOS) have been widely used for the consolidation of decaying stone heritages. These products polymerize within the porous structure of the decaying stone, significantly increasing the cohesion of the material. However, TEOS-based consolidants suffer from practical drawbacks, such as crack formation of the gel during the drying phase due to the developed capillary force, which is typical for TEOS-based consolidants. We have prepared new consolidants TEOS-based consolidants containing flexible (3-glycidoxypropyl) trimethoxysilane (GPTMS) and silica nanoparticles in order to reduce capillary force development during gel drying, and have characterized them for the application of stone consolidants. Different sizes of silica nanoparticles were used, which were smaller than the pore size of the tested stone. The properties of the TEOS/GPTMS/nanoparticle composite solution were compared with those of the commercial products Wacker OH and Unil sandsteinfestiger OH 1:1. The gelation time was similar to that of commercial consolidants, and the TEOS/GPTMS/nanoparticle solution was stable over a period of up to six months. The contact angle of the surface increased with the addition of the nanoparticle, as well as with the addition the GPTMS, which is higher than that of commercial Wacker OH. The addition of a nanoparticle, as well as GPTMS having flexible segment, provided a crack-free material, while the gels obtained from the commercial consolidants exhibited cracking.     

Study on some sorption properties of treated bentonites for their potential use as a moisture regulating system for the preservation of historical wooden elements

We report the first results of a research study aimed at developing a new strategy for the conservation of wooden structural elements present in historical buildings, based on moisture regulating systems. As has been happening for artefact preservation in museums, the idea is to develop systems based on the ability of some highly hygroscopic materials to moderate variations in relative humidity. These materials could adsorb and release moisture to reduce the extreme values of humidity in the micro-climate, for example between wooden beams and masonry. In order to experimentally verify this possibility using current, low cost and easy handling building materials, 5 bentonite samples were laboratory processed to improve their adsorbing properties by means of treatment with sodium carbonate at 3 concentrations: 2, 3 and 4% by weight. The effectiveness of ion exchange between sodium carbonate and bentonite was controlled by measuring the swelling volume of the bentonites. All the samples (n = 15) were tested for their hygroscopic properties. Adsorption isotherms were measured at 25 °C, using desiccators with silica gel, saturated salt solutions and bi-distilled water. A comparison between isotherms of one of the lower hygroscopic treated sample of bentonite and of a sample of wood and of a sample of brick and some numerical analyses with the Delphin code were made in order to evaluate the potential use of this bentonite as a moisture regulating system for the preservation of historical wooden elements. Results show that it seems to be possible to use bentonites as a moisture buffering material in order to reduce moisture content in wooden beams at least during their adsorption phase. It remains to investigate their desorption phase and their behaviour if they be in a saturation condition. Further studies are currently under way.     

Investigations regarding the behaviour of historic glass and its surface layers towards different wavelengths applied for laser cleaning

The application of lasers for the removal of superficial deposits from historic stained glass is a comparatively new field of scientific interest. Experimental studies concerning the behaviour of glass substrates and the corresponding superficial deposits towards different laser wavelengths were carried out. The experiments were performed using wavelengths of λ = 193 nm (ArF-Excimer), 308 nm (XeCl-Excimer), 355 nm (Nd:YAG third harmonic) and 1 064 nm (Nd:YAG fundamental) in comparison to λ = 248 nm (KrF-Excimer). This comparison is due to the fact that the present knowledge is based on the 248 nm wavelength. Specially prepared model glass samples representing the original fragments and samples of organic polymers (formerly used as a protective material for historic stained glasses) were used to study the effects of laser radiation and were subsequently characterised by optical microscopy.