Adsorption kinetics of acetic acid into ZnO/castor oil-derived polyurethanes.

HYPOTHESIS: Materials and colloids science can provide significant contributions to the conservation of Cultural Heritage. Hybrid systems made of a castor oil-derived polymeric network and a disperse phase of zinc oxide particles (ZnO/COPs) can be more effective absorbers of acetic acid (AcOH, a major pollutant harmful to artifacts in museums and art collections) than state-of-the-art materials, provided the acid uptake mechanism by the hybrids is elucidated and optimized. The starting hypothesis was that the polymer matrix might act as transporter, while acid adsorption would take place at the ZnO particles surface. The effect of particles size was expected to play a significant role. EXPERIMENTS: The adsorption kinetics of the hybrids were studied in the 23-45˚C range, in comparison with activated charcoal, the benchmark employed by conservators. Morphological and fractal dimension of ZnO micro- and nano-particles in the hybrid networks were investigated and correlated to the adsorption kinetics. FINDINGS: The presence of a two-steps mechanism for AcOH uptake by the hybrids was demonstrated for the first time: a combination of Fickian diffusion and Case-II transport occurs in the COP matrix, and adsorption dominates acid uptake (followed by neutralization) at the particles surface. This mechanism is likely key to explain the enhanced performances of the hybrids vs activated charcoal and state-of-the-art tools to remove AcOH. The hybrids have high uptake capacity, and lower activation energies for the removal process than materials where the uptake of acid relies solely on adsorption. The size of the ZnO particles contributes to the process, i.e. nanoparticles form smaller and ramified fractal clusters that are able to adsorb AcOH more effectively than microparticles. These insights demonstrated the efficacy of the novel hybrids in art conservation, where the control of minimal concentrations of VOCs is crucial for the preventive conservation of masterpieces, and can be useful to other fields where efficient capture of acetic acid is critical (food industry, textile dyeing/printing, etc.).

Environmentally friendly ZnO/Castor oil polyurethane composites for the gas-phase adsorption of acetic acid.

HYPOTHESIS: Acetic acid, a common pollutant present in museums and art galleries, can irreversibly damage works of art. Herein, a sustainable and scalable synthesis of zinc oxide-castor oil polyurethane hybrids (ZnO/COPs), to be used as acetic acid removers in the preventive conservation of Cultural Heritage, is reported. EXPERIMENTS: The adsorption capacities of ZnO/COPs were studied in saturated acetic acid atmosphere, at low acetic acid gas concentration, and inside a wooden crate (naturally emitting acetic acid) representative of those used in the storage deposits of museums and art collections. FINDINGS: Upon exposure, acetic acid interacts with the castor oil polyurethane and diffuses to the surface of ZnO particles where is stably fixed as zinc acetate crystals. Zinc acetate domains form homogeneously on the surface and are distributed evenly within the ZnO/COPs, thanks to weak interactions between the polyurethane matrix and acetic acid that favour the transport of the acid up to reach the zinc oxide surfaces, resulting in a synergistic effect. The ZnO/COPs composites showed significantly enhanced adsorption capacities of acetic acid surpassing those of the activated carbon benchmark, with the advantage of being easily handled and movable, without the health issues and risks associated to the use of non-confined micro/nano-powders.

Jin Shofu Starch Nanoparticles for the Consolidation of Modern Paintings.

Matte, porous, and weakly bound paint layers, typically found in modern/contemporary art, represent an unsolved conservation challenge. Current conservation practice relies on synthetic or natural adhesives that can alter dramatically the optical properties of paints. Alternatively, we propose a novel nanostructured consolidant based on starch, a renewable natural polymer. We synthesized starch nanoparticles (SNPs) to boost their penetration into the porous painted layers; upon solvent evaporation, the particles were expected to adhere to the pigments thanks to their large surface area and abundant -OH groups. The SNPs were formulated through a bottom-up approach, where gluten-removed Jin Shofu wheat starch was gelatinized and then precipitated in a nonsolvent. The low gelatinization temperature of wheat starch is likely key to favor disassembly in alkali and reassembly in the nonsolvent. The synthesis conditions can be tuned to obtain amorphous SNPs of ca. 50 nm with acceptable polydispersity. The particles swell in water to form nanosized gel-like fractal domains (as observed with cryogenic electron microscopy), formed by the organization of smaller units in polymer-rich and -deficient regions. Aqueous and hydroalcoholic particles' dispersions were assessed on aged ultramarine blue mock-ups that mimic degraded modern/contemporary paints. The consolidation effectiveness was evaluated with a specifically designed in-house protocol: the SNPs distribute across the paint section and strongly increase pigments' cohesion while preserving the original optical properties of the painted layer, as opposed to dispersions of bulk starch that simply accumulate on the paint surface, forming superficial glossy films. The Jin Shofu SNPS proved to be a new promising tool for the consolidation of weakened paintings, opening perspectives in the formulation and application of consolidants for modern and contemporary art.

Selective removal of over-paintings from "Street Art" using an environmentally friendly nanostructured fluid loaded in highly retentive hydrogels.

HYPOTHESIS: The removal of over-paintings or graffiti is a priority for conservators and restorers. This operation is complex, especially when over-paintings lay on painted surfaces that must be preserved, as in the case of vandalism on street art, where the layers are usually chemically similar. Traditional methodologies often do not provide satisfactory results and pose health and eco-compatibility concerns. An alternative methodological approach based on an environmentally friendly nanostructured fluid loaded in a retentive hydrogel is here proposed. EXPERIMENTS: Six paints (based on vinyl, acrylic and alkyd polymers) were selected and studied by means of attenuated total reflection - Fourier transform infrared spectroscopy. The phase behavior of four alkyl carbonates (green, low-toxicity organic solvents) and a biodegradable nonionic surfactant in water was investigated with Small angle X-ray scattering (SAXS) in order to formulate a novel nanostructured cleaning system. The developed system, which also includes 2-butanol and an alkyl glycoside hydrotrope, was loaded in highly retentive hydrogels and tested in the selective removal of over-paintings from laboratory mockups and from real pieces of street art. FINDINGS: The selective and controlled removal of modern paints from substrates with similar chemical composition has been achieved using a specifically tailored NSF embedded in a retentive hydrogel. The proposed methodology and cleaning system provided excellent cleaning results, representing a new tool for the conservation of contemporary and, in particular, street art.

Nanomaterials for Combined Stabilisation and Deacidification of Cellulosic Materials-The Case of Iron-Tannate Dyed Cotton.

The conservation of textiles is a challenge due to the often fast degradation that results from the acidity combined with a complex structure that requires remediation actions to be conducted at several length scales. Nanomaterials have lately been used for various purposes in the conservation of cultural heritage. The advantage with these materials is their high efficiency combined with a great control. Here, we provide an overview of the latest developments in terms of nanomaterials-based alternatives, namely inorganic nanoparticles and nanocellulose, to conventional methods for the strengthening and deacidification of cellulose-based materials. Then, using the case of iron-tannate dyed cotton, we show that conservation can only be addressed if the mechanical strengthening is preceded by a deacidification step. We used CaCO3 nanoparticles to neutralize the acidity, while the stabilisation was addressed by a combination of nanocellulose, and silica nanoparticles, to truly tackle the complexity of the hierarchical nature of cotton textiles. Silica nanoparticles enabled strengthening at the fibre scale by covering the fibre surface, while the nanocellulose acted at bigger length scales. The evaluation of the applied treatments, before and after an accelerated ageing, was assessed by tensile testing, the fibre structure by SEM and the apparent colour changes by colourimetric measurements.

Self-regenerated silk fibroin with controlled crystallinity for the reinforcement of silk.

HYPOTHESIS: Silk artifacts constitute a fundamental cultural and historical heritage, yet they are affected by degradation that alters the secondary structure of fibroin and weakens the mechanical properties of textiles, hindering their conservation. Feasible and compatible consolidants for silk are still widely needed. EXPERIMENTS: Here, we propose a robust and reliable method to restore the mechanical properties of fragile, aged silk fibers, based on the adhesion of self-regenerated silk fibroin (SRSF) with controlled crystallinity, prepared from waste silk, to the aged fibers. By varying the concentration of fibroin dispersions, the content of crystalline and amorphous domains in SRSF films can be tuned, as demonstrated by 2D micro-Fourier transform infrared spectroscopy Imaging and thermal analysis. FINDINGS: The presence of amorphous fibroin domains, distributed between the aged silk fibers, completely recovered their mechanical properties. Instead, the presence of domains with high content of ordered structures, distributed between the fibers, reduced their tensile strength and elongation length. The different mechanical behavior is likely due to the fact that adhesion of crystalline layers produces a brittle material, while amorphous layers with higher fibroin chain mobility increase ductility. The tunability of this treatment allows easy control of desired mechanical properties of degraded silk fibers, simply controlling the crystallinity Vs amorphousness of SRSF; these findings open up new perspectives in textile conservation, in the engineering of biomaterials and materials, and in the preparation of composite materials with enhanced properties.

Raman Spectroscopy and Surface Enhanced Raman Scattering (SERS) for the Analysis of Blue and Black Writing Inks: Identification of Dye Content and Degradation Processes.

Raman spectroscopy and Surface Enhanced Raman Scattering (SERS) were applied to the analysis of blue and black writing inks. SERS was performed by application of plasmonic nanopastes constituted by Ag nanoparticles and Au nanorods directly on inks deposited on paper substrates under laser irradiation of 514 nm. It was found that SERS spectra were largely enhanced compared to Raman spectra and that Ag nanopastes produced much larger enhancements than Au nanopastes, due to a combination of plasmonic resonance, charge transfer, and molecular resonance effects. All analyzed writing inks resulted constituted by Crystal Violet and other triarylmethane dye mixtures, to which sometimes phthalocyanine dyes were also added (for example in Bic pens). SERS was also used for the identification of degradation processes occurring in artificially aged blue pens deposited on paper substrates. It was found that color alteration changed from ink to ink and varied from darkening to discoloration to slight fading, depending on the initial chemical composition. For inks containing Crystal Violet, two mechanisms associated to de-methylation and photo-reduction of excited dye to colorless leuco forms were identified.

Understanding the structural degradation of South American historical silk: A Focal Plane Array (FPA) FTIR and multivariate analysis.

Silk artifacts constitute an invaluable heritage, and to preserve such patrimony it is necessary to correlate the degradation of silk fibroin with the presence of dyes, pollutants, manufacturing techniques, etc. Fourier Transform Infrared Spectroscopy with a Focal plane array detector (FPA FTIR) provides structural information at the micron scale. We characterized the distribution of secondary structures in silk fibers for a large set of South American historical textiles, coupling FTIR with multivariate statistical analysis to correlate the protein structure with the age of the samples and the presence of dyes. We found that the pressure applied during attenuated total reflectance (ATR) measurements might induce structural changes in the fibers, producing similar spectra for pristine and aged samples. Reflectance spectra were thus used for the rigorous characterization of secondary structures. Some correlation was highlighted between the age of the samples (spanning over five centuries) and specific changes in their secondary structure. A correlation was found between the color of the samples and structural alterations, in agreement with the chemical nature of the dyes. Overall, we demonstrated the efficacy of reflectance FPA µ-FTIR, combined with multivariate analysis, for the rigorous and non-invasive description of protein secondary structures on large sets of samples.

Hybrid nano-composites for the consolidation of earthen masonry.

HYPOTHESIS: Earth is one of the oldest silicate-based materials in stone heritage, still largely used in architecture worldwide. Earthen materials are highly susceptible to wind and water erosion, leading to loss of cohesion and crumbling. Conventional consolidants (alkoxysilanes, synthetic or natural polymers) lack physico-chemical compatibility or effectiveness, and can promote degradation. We propose for the first time nano-composites for the surface consolidation of adobe, i.e. unbaked earth bricks often containing organic fibers and lime. EXPERIMENTS: We investigated, mimicking the setting of portland cement, the formation of calcium silicate hydrate (CSH) within adobe porosities, owing to the pozzolanic reaction between nanoparticles of silica and calcium hydroxide, to consolidate a powdery substrate. Different formulations were characterized by Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM), dynamic light scattering (DLS), and turbidimetry (UV-Vis spectroscopy). FINDINGS: A ternary composite made of SiO2 nanoparticles, Ca(OH)2 nanoparticles, and hydroxypropyl cellulose, dispersed in a (4:1) ethanol:water blend, was formulated. Each component is compatible with adobe, and plays a role in its consolidation. The treatment of adobe samples with the composite leads to the in situ formation of CSH, providing resistance to peeling, abrasion, and wet-dry cycles, with no aesthetic alteration. This opens new perpectives in the preservation of one of the most widely used construction materials.

Poly(vinyl alcohol)/poly(vinyl pyrrolidone) hydrogels for the cleaning of art.

The cleaning of modern and contemporary paintings is a delicate and challenging operation. Many contemporary paintings exhibit rough, clotted and pitted surfaces, where the removal of soil is difficult. Gels are among the most efficient tools to achieve controlled and efficient cleaning of works of art. However, most gels used in the conservation practice are too rigid to adapt rough surfaces, or too mechanically weak to be removed without leaving polymer residues. Several formulations of physically cross-linked poly(vinyl alcohol) (PVA)-based hydrogels, obtained by cast-drying or freeze-thawing of aqueous polymeric solutions, were formulated and characterized. The viscoelastic properties, porosity, and crystallinity of the gels were studied, along with the behavior of water inside the polymeric network. It was shown that the properties of the gels were improved through blending with poly(vinyl pyrrolidone) (PVP). The most promising gel formulation, in terms of mechanical properties and water retentiveness, was assessed for the removal of soil from an alkyd painting mock-up. A traditional gel, gellan gum, was also tested as a reference system. The effectiveness of soil removal was investigated by 2D Fourier transform infrared (FTIR) microscopy, using a Focal Plane Array (FPA) detector. In conclusion, it was shown that the newly developed formulation grants the residue-free removal of soil from rough and irregular artistic surfaces, overcoming the limits of traditional cleaning methods.

Nonaqueous Microemulsion in the Bmim Tf2N/Brij 30/ n-Nonane System: Structural Investigation and Application as Gold Nanoparticle Microreactor.

Microemulsions based on ionic liquids (ILs) are being increasingly studied in many different areas of physical chemistry because of the attractive properties of ILs. In particular, waterless microemulsions where the IL represents the polar phase can be of interest for those applications that demand the nanosegregation of polar substances, but in which the absence of water is a strict requirement. In this work, we prepared a reverse, nonaqueous microemulsion based on the low-viscosity room-temperature IL, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide , the surfactant Brij 30, and n-nonane. The systems were characterized by dynamic light scattering and small-angle X-ray scattering; the IL/oil microemulsion was further employed as a templating system for the synthesis of gold nanoparticles from hydrogen tetrachloroaurate(III), HAuCl4, by UV-photoreduction technique.

A Triton X-100-Based Microemulsion for the Removal of Hydrophobic Materials from Works of Art: SAXS Characterization and Application.

The removal of hydrophobic materials from a porous support, such as wax stains on wall paintings, is particularly challenging. In this context, traditional methods display several drawbacks. The limitations of these methods can be overcome by amphiphile-based aqueous nanostructured fluids, such as micellar solutions and microemulsions. In this study, a microemulsion for the removal of wax spots from artistic surfaces was formulated. The nanostructured fluid includes a non-ionic surfactant, i.e., Triton X-100, and two apolar solvents, namely p-xylene and n-nonane. The solvents were selected on the basis of solubility tests of three waxes in several organic solvents. The nanostructured fluid was characterized by means of small-angle X-rays scattering (SAXS) and the information about micelle structure was used to understand the interaction between the microemulsion and the selected waxes. The microemulsion was then tested during the restoration of the frescoes in the Major Chapel of the Santa Croce Basilica in Florence, Italy. After some preliminary tests on fresco mockups reproduced in the laboratory, the nanostructured fluid was successfully used to clean some wax deposits from the real paintings, hardly removable with traditional physico-mechanical methods.

Complex Fluids Confined into Semi-interpenetrated Chemical Hydrogels for the Cleaning of Classic Art: A Rheological and SAXS Study.

The removal of aged varnishes from the surface of easel paintings using the common conservation practice (i.e., by means of organic solvents) often causes pigment leaching, paint loss, and varnish redeposition. Recently, we proposed an innovative cleaning system based on semi-interpenetrated polymer networks (SIPNs), where a covalently cross-linked poly(hydroxyethyl methacrylate), pHEMA, network is interpenetrated by linear chains of poly(vinylpyrrolidone), PVP. This chemical gel, simply loaded with water, was designed to safely remove surface dirt from water-sensitive artifacts. Here, we modified the SIPN to confine complex cleaning fluids, able to remove aged varnishes. These complex fluids are 5-component water-based nanostructured systems, where organic solvents are partially dispersed as nanosized droplets in a continuous aqueous phase, using surfactants. The rheological behavior of the SIPN and the nanostructure of the fluids loaded into the gel were investigated, and the mechanical behavior of the gel was optimized by varying both the cross-linking density and the polymer concentration. Once loaded with the complex fluids, the hydrogels maintained their structural and mechanical features, while the complex fluids showed a decrease in the size of the dispersed solvent droplets. Two challenging case studies have been selected to evaluate the applicability of the SIPN hydrogels loaded with the complex fluids. The first case study concerns the removal of a surface layer composed by an aged brown resinous patina from a wood panel, the second case study concerns the removal of a homogeneous layer of yellowed varnish from a watercolor on paper. The results show that the confinement of complex fluids into gels allowed unprecedented removal of varnishes from artifacts overcoming the limitations of traditional cleaning methods.

A combined Surface Enhanced Raman Spectroscopy (SERS)/UV-vis approach for the investigation of dye content in commercial felt tip pens inks.

The development of protocols for the protection of the large patrimony of works of art created by felt tip pen media since the 1950's requires detailed knowledge of the main dyes constituting commercial ink mixtures. In this work Surface Enhanced Raman Scattering (SERS) and UV-vis spectroscopy were used for the first time for the systematic identification of dye composition in commercial felt tip pens. A large selection of pens comprising six colors of five different brands was analyzed. Intense SERS spectra were obtained for all colors, allowing identification of main dye constituents. Poinceau 4R and Eosin dyes were found to be the main constituents of red and pink colors; Rhodamine and Tartrazine were found in orange and yellow colors; Erioglaucine was found in green and blue colors. UV-vis analysis of the same inks was used to support SERS findings but also to unequivocally assign some uncertain dye identifications, especially for yellow and orange colors. The spectral data of all felt tip pens collected through this work were assembled in a database format. The data obtained through this systematic investigation constitute the basis for the assembly of larger reference databases that ultimately will support the development of conservation protocols for the long term preservation of modern art collections.

Microemulsions, Micelles, and Functional Gels: How Colloids and Soft Matter Preserve Works of Art.

Colloid science provides fundamental knowledge to fields such as the pharmaceutical, detergency, paint, and food industry. An exciting application is art conservation, which poses a challenge owing to the complex range of interfacial interactions involved in restoring artefacts. Currently, the majority of the most performing and environmentally safe cleaning and consolidation agents for artworks belong to soft matter and colloids. The development and application of increasingly complex systems, from microemulsions to semi-interpenetrating hydrogels containing such fluids, is presented. These systems have been used on diverse artefacts, from Renaissance frescos to works by Picasso and Pollock. Chemical design can be implemented to meet the requirements of curators, and knowledge of the colloid structure and dynamics can overcome serendipitous approaches of traditional conservation practice. Future perspectives for soft matter and colloid science in the field of cultural heritage preservation are also summarized.

Polymer Film Dewetting by Water/Surfactant/Good-Solvent Mixtures: A Mechanistic Insight and Its Implications for the Conservation of Cultural Heritage.

Aqueous nanostructured fluids (NSFs) have been proposed to remove polymer coatings from the surface of works of art; this process usually involves film dewetting. The NSF cleaning mechanism was studied using several techniques that were employed to obtain mechanistic insight on the interaction of a methacrylic/acrylic copolymer (Paraloid B72) film laid on glass surfaces and several NSFs, based on two solvents and two surfactants. The experimental results provide a detailed picture of the dewetting process. The gyration radius and the reduction of the Tg of Paraloid B72 fully swollen in the two solvents is larger for propylene carbonate than for methyl ethyl ketone, suggesting higher mobility of polymer chains for the former, while a nonionic alcohol ethoxylate surfactant was more effective than sodium dodecylsulfate in favoring the dewetting process. FTIR 2D imaging showed that the dewetting patterns observed on model samples are also present on polymer-coated mortar tiles when exposed to NSFs.

Plasmonic colloidal pastes for surface-enhanced Raman spectroscopy (SERS) of historical felt-tip pens.

Surface-enhanced Raman spectroscopy (SERS) has been identified as a suitable technique for the analysis of colorants in works of art. Herein, the application of SERS to the identification of dye compositions in historical felt-tip pens is reported, which is of paramount importance for the development of appropriate conservation protocols for historical drawings. In this study, three pens (pink, green, and blue colors) belonging to the film director Federico Fellini were analyzed. SERS measurements were performed directly on the pen lines drawn on a commercial paper by the deposition of Ag colloidal pastes, which allowed fast in situ dye identification without the need for extraction or hydrolysis treatments. Eosin Y was identified as the only dye present in the pink pen ink, whereas erioglaucine was found to be the main dye component in green and blue pen inks. SERS also resulted in highly efficient identification of the individual dyes erioglaucine, crystal violet, and rhodamine present as a mixture in the blue pen ink. The high SERS sensitivity was ascribed to the plasmonic effects and efficient quenching of the fluorescence interference of dyes. A comparison with contemporary pen inks highlighted minor differences in the chemical composition. These results prove that SERS can be used as a fast and sensitive analytical tool for ink analysis that provides invaluable support for the general assessment of the date, provenance, and originality of the historical drawings as well as for the development of preventive conservation protocols.

Nanofluids and chemical highly retentive hydrogels for controlled and selective removal of overpaintings and undesired graffiti from street art.

One of the main problems connected to the conservation of street art is the selective removal of overlying undesired graffiti, i.e., drawings and tags. Unfortunately, selective and controlled removal of graffiti and overpaintings from street art is almost unachievable using traditional methodologies. Recently, the use of nanofluids confined in highly retentive pHEMA/PVP semi-interpenetrated polymer networks was proposed. Here, we report on the selective removal of acrylic overpaintings from a layer of acrylic paint on mortar mockups in laboratory tests. The results of the cleaning tests were characterized by visual and photographic observation, optical microscopy, and FT-IR microreflectance investigation. It was shown that this methodology represents a major advancement with respect to the use of nonconfined neat solvents.

Calcium hydroxide nanoparticles from solvothermal reaction for the deacidification of degraded waterlogged wood.

HYPOTHESIS: A combination of acid and iron ions inside the wood has been corroding the cellulose matrix of the Swedish warship Vasa, imposing its deacidification. Past deacidification treatments displayed poor penetration inside the wood matrix with limited efficacy. A vacuum assisted treatment of wood using newly developed calcium hydroxide nanoparticle dispersions represents a possible candidate for the treatment of acidic waterlogged wood objects such as sculptures and decorative artifacts. EXPERIMENTS: A solvothermal process was used for the synthesis of calcium hydroxide nanoparticle dispersions. Before the application on waterlogged wood, the physico-chemical characterization of these systems was carried out using several techniques. The efficacy of the deacidification treatment of wood samples from the Vasa was assessed by determination of pH and Differential Thermal Gravimetric (DTG) measurements. FINDINGS: The proposed solvothermal reactions can be used to produce stable and highly concentrated calcium hydroxide nanoparticle dispersions in alcohols, needing no further purification before the application. This process has also the advantage to be upscalable to industrial level. Both pH and DTG measurements showed that the newly developed dispersions can homogenously penetrate inside the wood up to 20cm, neutralizing acidity and creating an alkaline buffer inside the wooden matrix, to hinder the degradation of residual cellulose.

Morpho-chemical characterization and surface properties of carcinogenic zeolite fibers.

Erionite belonging to the zeolite family is a human health-hazard, since it was demonstrated to be carcinogenic. Conversely, offretite family zeolites were suspected carcinogenic. Mineralogical, morphological, chemical, and surface characterizations were performed on two erionites (GF1, MD8) and one offretite (BV12) fibrous samples and, for comparison, one scolecite (SC1) sample. The specific surface area analysis indicated a larger availability of surface sites for the adsorption onto GF1, while SC1 shows the lowest one and the presence of large pores in the poorly fibrous zeolite aggregates. Selected spin probes revealed a high adsorption capacity of GF1 compared to the other zeolites, but the polar/charged interacting sites were well distributed, intercalated by less polar sites (Si-O-Si). MD8 surface is less homogeneous and the polar/charged sites are more interacting and closer to each other compared to GF1. The interacting ability of BV12 surface is much lower than that found for GF1 and MD8 and the probes are trapped in small pores into the fibrous aggregates. In comparison with the other zeolites, the non-carcinogenic SC1 shows a poor interacting ability and a lower surface polarity. These results helped to clarify the chemical properties and the surface interacting ability of these zeolite fibers which may be related to their carcinogenicity.