Historical iron gall ink containing documents — Properties affecting their condition

Novel Graphene-Based Materials as a Tool for Improving Long-Term Storage of Cultural Heritage

The very serious problem of temperature and humidity regulation, especially for small and medium-sized museums, galleries, and private collections, can be mitigated by the introduction of novel materials that are easily applicable and of low cost. Within this study, archive boxes with innovative technology are proposed as "smart" boxes that can be used for storage and transportation, in combination with a nanocomposite material consisting of polyvinyl alcohol (PVA) and graphene oxide (GO). The synthesis and characterization of the PVA/GO structure with SEM, Raman, AFM, XRD, Optical Microscopy, and profilometry are fully discussed. It is shown that the composite material can be integrated into the archive box either as a stand-alone film or attached onto fitting carriers, for example, those made of corrugated board. By applying the PVA/GO membrane this way, even with strong daily temperature fluctuations of ΔT = ±24.1 °C, strong external humidity fluctuations can be reduced by -87% inside the box. Furthermore, these humidity regulators were examined as Volatile Organic Compounds (VOCs) adsorbers since gas pollutants like formic acid, formaldehyde, acetic acid, and acetaldehyde are known to exist in museums and induce damages in the displayed or stored items. High rates of VOC adsorption have been measured, with the highest ones corresponding to formic acid (521% weight increase) and formaldehyde (223% weight increase).

A holistic approach to understanding the iron-gall inks in the historical documents of the Portuguese Inquisition (1570-1790)

A substantial part of our written heritage is threatened by the fact that much of it has been written using iron-gall ink (IGI). One such example is the documents of the Portuguese Inquisition Tribunals, held by the Arquivo Nacional da Torre do Tombo. Here we present the first systematic analytical approach, using SEM/EDS, µ-FT-IR-ATR and µ-Raman techniques, to characterise fragments from historical records of the Inquisition Tribunals of Évora, Lisboa and Coimbra from the 16th to 18th centuries. The writing ink was identified as IGI, providing complementary compositional data and establishing differences between various formulations of the ink. Additionally, the deleterious effects of the inks-associated degradation phenomena were highlighted. This work allowed understand the writing inks used by this Portuguese institution.

A Model Iron Gall Ink: An In-Depth Study of Ageing Processes Involving Gallic Acid

Iron gall inks have been among the most used writing materials after carbon black, thus representing an important element of the historical and artistic heritage of our society. Crucially, the preservation of manuscripts and drawings is influenced by the presence of these inks, leading to conservation issues related to paper degradation and text fading. Besides all the advances obtained in paper conservation, the study of iron gall ink's behaviour and ageing is still an important topic, which requires investigation through an accurate molecular characterisation to produce reliable models. In the present work a micro-destructive method based on liquid chromatography techniques (HPLC-DAD and HPLC-ESI-Q-ToF) has been optimised starting from a model gallic acid-based ink. An in-depth study of the behaviour of the ink in time was performed by natural and artificial ageing tests, monitored by colorimetry, showing the autoxidation of gallic acid to ellagic acid in the prepared mock-ups. The effect of relative humidity on ageing processes was also evaluated, allowing us to determine different intermediates depending on the environmental conditions. Finally, the analytical method developed was then successfully applied for investigating 19th-20th century historical ink samples, where one of the identified ageing markers was detected, besides the expected gallic and ellagic acids.

Sustainable wood electronics by iron-catalyzed laser-induced graphitization for large-scale applications

Ecologically friendly wood electronics will help alleviating the shortcomings of state-of-art cellulose-based “green electronics”. Here we introduce iron-catalyzed laser-induced graphitization (IC-LIG) as an innovative approach for engraving large-scale electrically conductive structures on wood with very high quality and efficiency, overcoming the limitations of conventional LIG including high ablation, thermal damages, need for multiple lasing steps, use of fire retardants and inert atmospheres. An aqueous bio-based coating, inspired by historical iron-gall ink, protects wood from laser ablation and thermal damage while promoting efficient graphitization and smoothening substrate irregularities. Large-scale (100 cm²), highly conductive (≥2500 S m⁻¹) and homogeneous surface areas are engraved single-step in ambient atmosphere with a conventional CO₂ laser, even on very thin (∼450 µm) wood veneers. We demonstrate the validity of our approach by turning wood into highly durable strain sensors, flexible electrodes, capacitive touch panels and an electroluminescent LIG-based device.

Ecologically friendly wood electronics will help alleviating the shortcomings of state-of-art cellulose-based green electronics. Here, the authors introduce iron-catalyzed laser-induced graphitization (IC-LIG) as an innovative approach for engraving large-scale electrically conductive structures on wood with high quality and efficiency.

Iron Gall Ink Corrosion on Parchment. Preliminary Evaluation of Treatment Methods Using Aqueous Solutions

Ink corrosion on parchment is a phenomenon that, unlike its counterpart on paper, has so far been little researched. The same applies to the options for conservation treatment. In order to provide a guide for conservation practice as well as further research, five water-based treatment methods were examined: calcium phytate with pH 5.3 or 3.0, a 0.5% (w/w) solution type B gelatine, a 1% (w/w) solution of phytic acid at pH 2.2 and calcium phytate in combination with gelatine. These were tested on 70 specimens cut from on piece of buffed vellum and 36 specimens from an early modern deed on parchment that showed signs of ink degradation. After treatment and accelerated ageing, the samples were examined with colorimetry and ATR-FTIR spectroscopy and tested with bathophenanthroline for free iron ions. None of the tested treatment methods achieved a fully reliable inhibition of ink corrosion, but apart from a moisture-catalysed acceleration of degradation reactions, no adverse effects were observed either. Results from ATR-FTIR suggest that oxidation plays a more important role in damage related to ink corrosion of parchment than hydrolysis.

Biomedical applications of tannic acid

Tannic Acid (TA) is a naturally occurring antioxidant polyphenol that has gained popularity over the past decade in the field of biomedical research for its unique biochemical properties. Tannic acid, typically extracted from oak tree galls, has been used in many important historical applications. TA is a key component in vegetable tanning of leather, iron gall ink, red wines, and as a traditional medicine to treat a variety of maladies. The basis of TA utility is derived from its many hydroxyl groups and its affinity for forming hydrogen bonds with proteins and other biomolecules. Today, the study of TA has led to the development of many new pharmaceutical and biomedical applications. TA has been shown to reduce inflammation as an antioxidant, act as an antibiotic in common pathogenic bacterium, and induce apoptosis in several cancer types. TA has also displayed antiviral and antifungal activity. At certain concentrations, TA can be used to treat gastrointestinal disorders such as hemorrhoids and diarrhea, severe burns, and protect against neurodegenerative diseases. TA has also been utilized in biomaterials research as a natural crosslinking agent to improve mechanical properties of natural and synthetic hydrogels and polymers, while also imparting anti-inflammatory, antibacterial, and anticancer activity to the materials. TA has also been used to develop thin film coatings and nanoparticles for drug delivery. In all, TA is fascinating molecule with a wide variety of potential uses in pharmaceuticals, biomaterials applications, and drug delivery strategies.

Vibrational Study (Raman, SERS, and IR) of Plant Gallnut Polyphenols Related to the Fabrication of Iron Gall Inks

FT-Raman, FTIR, and SERS spectra of the structurally related gallnut polyphenols tannic acid, gallic acid, pyrogallol, and syringic acid are reported in this work aiming at performing a comparative assignation of the bands and finding specific marker features that can identify these compounds in complex polyphenol mixtures. Tannic and gallic acids are the principal components in oak gallnuts, and they can be found in iron gall inks. The different functional groups existing in these molecules and their spatial distribution lead to slight changes of the vibrations. The Raman spectra are dominated by bands corresponding to the ring vibrations, but the substituents in the ring strongly affect these vibrations. In contrast, the FTIR spectra of these molecules are dominated by the peripheral oxygen-containing substituents of the aromatic ring and afford complementary information. SERS spectroscopy can be used to analyze trace amounts of these compounds, but the spectra of these polyphenols show strong changes in comparison with the Raman spectra, indicating a strong interaction with the metal. The most significant modification observed in the SERS spectra of these compounds is the weakening of the benzene 8a ring vibration and the subsequent intensification of the 19a mode of the benzene ring. This mode is also more intense in the FTIR spectra, and its intensification in the SERS spectra could be related to a drastic change in the molecular polarizability associated with the interaction of the polyphenol with the metal in Ag NPs.

A Smart Archive Box for Museum Artifact Monitoring Using Battery-Less Temperature and Humidity Sensing

For the first time, this paper reports a smart museum archive box that features a fully integrated wireless powered temperature and humidity sensor. The smart archive box has been specifically developed for microclimate environmental monitoring of stored museum artifacts in cultural heritage applications. The developed sensor does not require a battery and is wirelessly powered using Near Field Communications (NFC). The proposed solution enables a convenient means for wireless sensing with the operator by simply placing a standard smartphone in close proximity to the cardboard archive box. Wireless sensing capability has the advantage of enabling long-term environmental monitoring of the contents of the archive box without having to move and open the box for reading or battery replacement. This contributes to a sustainable preventive conservation strategy and avoids the risk of exposing the contents to the external environment, which may result in degradation of the stored artifacts. In this work, a low-cost and fully integrated NFC sensor has been successfully developed and demonstrated. The developed sensor is capable of wirelessly measuring temperature and relative humidity with a mean error of 0.37 °C and ±0.35%, respectively. The design has also been optimized for low power operation with a measured peak DC power consumption of 900 μW while yielding a 4.5 cm wireless communication range. The power consumption of the NFC sensor is one of the lowest found in the literature. To the author’s knowledge, the NFC sensor proposed in this paper is the first reporting of a smart archive box that is wirelessly powered and uniquely integrated within a cardboard archive box.

Intratumoral synthesis of nano-metalchelate for tumor catalytic therapy by ligand field-enhanced coordination

The iron gall ink-triggered chemical corrosion of hand-written documents is a big threat to Western cultural heritages, which was demonstrated to result from the iron gall (GA-Fe) chelate-promoted reactive oxygen species generation. Such a phenomenon has inspired us to apply the pro-oxidative mechanism of GA-Fe to anticancer therapy. In this work, we construct a composite cancer nanomedicine by loading gallate into a Fe-engineered mesoporous silica nanocarrier, which can degrade in acidic tumor to release the doped Fe³⁺ and the loaded gallate, forming GA-Fe nanocomplex in situ. The nanocomplex with a highly reductive ligand field can promote oxygen reduction reactions generating hydrogen peroxide. Moreover, the resultant two-electron oxidation form of GA-Fe is an excellent Fenton-like agent that can catalyze hydrogen peroxide decomposition into hydroxyl radical, finally triggering severe oxidative damage to tumors. Such a therapeutic approach by intratumoral synthesis of GA-Fe nano-metalchelate may be instructive to future anticancer researches.

Iron gall chelate (GA-Fe) can promote oxygen reduction reactions and reactive oxygen species generation which causes chemical corrosion. Here, the authors, inspired by this phenomenon, develop a composite nanomedicine for tumour therapy constructed by loading gallate into Fe-engineered and PEGylated mesoporous silica nanocarrier, and show that it inhibits tumour growth.

In-depth phenolic characterization of iron gall inks by deconstructing representative Iberian recipes

Iron-gall ink is one of the most important inks in the history of western civilization. The deep black colour results from Fe³⁺ complexes with phenolic compounds available in gall extracts. Unfortunately, it induces the degradation of both ink and support over time. Furthermore, our knowledge of these complex molecular structures is limited. This work aims to overcome this gap, revealing essential information about the complex structures of these pigments and dyes that will create a breakthrough in the next generation of conservation treatments. It presents the first in-depth phenolic identification and quantification of extracts and inks, prepared with and without gum arabic (an essential additive in medieval recipes). Five representative Iberian recipes were selected and prepared. Their phenolic profile was analysed by HPLC–DAD and HPLC–ESI–MS, which revealed that the phenolic compounds present in higher concentration, in the gall extracts, are pentagalloylglucose and hexagalloylglucose (0.15 ± 0.01–32 ± 3 mg/mL), except for one recipe, in which gallic acid is the main phenolic. The influence of the ingredients is also discussed by deconstructing the recipes: extracts of additives as pomegranate peel and solvents used in the extraction of the galls (vinegar and white wine) were characterized.

Non-invasive approximation of elemental composition of historic inks by LA-ICP-MS measurements of bathophenanthroline indicators

The approximated identification of elemental composition of historic iron gall-inks is proposed based on results of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) measurements combined with a quick detection of iron (II) ions. Colorimetric response of test papers soaked with bathophenanthroline (BPhen) allows for detection of iron in the form of red-coloured complex of Fe(II) with BPhen. A co-migration of other elements (Cu, Zn, Pb, Al, K, Na, Mg) into indicators was confirmed by LA-ICP-MS measurements allowing for approximation of chemical diversity of handwritten documents in a totally non-invasive manner in respect to originals. The proposed analytical approach for in-direct studies of unique documents was tested on historic and model samples. The idea of approximation of elemental composition of the historic inks was found promising for purposes of conservation diagnosis towards estimation of corrosiveness of inks and eventual fingerprinting. It has been demonstrated that the presence of Fe as well as other elements (S, Cu and Mn) which are significant for recognition of ink corrosion can be detected in the used indicators extending the possibilities of examining valuable manuscripts in a way that is completely neutral for them.

Microscopic characterization of acidic paper manuscripts

Purpose

This paper aims to investigate the effect of acidity on the morphology of archeological paper, especially in the presence of colors and whether natural pigments play a role in the process of degradation.

Design/methodology/approach

The morphological changes in the cellulosic fibers of the manuscripts because of acidity were investigated using environmental scanning electron microscope (ESEM). Ten historical samples were collected from different manuscripts suffering from acidity. X-ray diffraction was used to identify the inks and pigments that were used in some samples. Additionally, Fourier transform infrared microscopy was used to identify the binding medium.

Findings

The results confirmed that carbon ink, ultramarine, cinnabar and gold pigments were applied to some manuscripts with Arabic gum. As for ESEM investigation, the results proved that acidity badly affected the integrity of the cellulosic fibers resulting in their embrittlement. The micrographs showed differences in fiber degradation according to pH value. The presence of inks and pigments increased the degradation extent resulting from acidity.

Originality/value

This paper addresses a specific need to study the behavior of degradation in paper manuscripts, thus helping the conservators find solutions to the phenomenon.

Browsing through sealed historical manuscripts by using 3-D computed tomography with low-brilliance X-ray sources

Severely damaged historical documents are extremely fragile. In many cases, their secrets remain concealed beneath their cover. Recently, non-invasive digitization approaches based on 3-D scanning have demonstrated the ability to recover single pages or letters without the need to open the manuscripts. This can even be achieved using conventional micro-CTs without the need for synchrotron hardware. However, not all manuscripts may be suited for such techniques due to their material and X-ray properties. In order to recommend which manuscripts and which inks are best suited for such a process, we investigate six inks that were commonly used in ancient times: malachite, three types of iron gall, Tyrian purple, and buckthorn. Image contrast is explored over the complete pipeline, from the X-ray CT scan and page extraction to the virtual flattening of the page image. We demonstrate, that all inks containing metallic particles are visible in the output, a decrease of the X-ray energy enhances the readability, and that the visibility highly depends on the X-ray attenuation of the ink’s metallic ingredients and their concentration. Based on these observations, we give recommendations on how to select the appropriate imaging parameters.

Linking Infrared Spectra of Laboratory Iron Gall Inks Based on Traditional Recipes with their Material Components

The question for discriminating iron gall inks is addressed by correlating their infrared (IR) spectra in liquid and dried states with the materials used in their formulations and considering their possible interactions. A series of laboratory inks were prepared according to historic recipes, mainly found in 19th-century documents, and were accordingly studied using Fourier transform infrared (FT-IR) spectroscopy. All ink formulations were based on Aleppo galls, ferrous sulfate, and gum arabic at variable proportions, with various added components, such as alum, vinegar, glycerol, sugar, silver nitrate, cloves, and white wine. Ingredients of the corresponding inks were recognized by means of their IR fingerprints in both their liquid and dried states, respectively. Although a few inks of distinct formulations showed discernible differences in their spectra, the majority showed quite similar absorptions. Principal component analysis and discriminant analysis were employed to successfully discriminate inks, based on their IR peaks. Spectra recorded in the liquid state, despite their broad absorption features, led to satisfactory discrimination of certain types of inks as most of their ingredients are reflected in their IR peaks. Spectra from dried inks contained similar information, which equally worked in a sufficient discriminatory way. Key IR peaks in the recorded spectra of inks made with the addition of special ingredients, such as vinegar, wine, alum, glycerol, and sugar, as well as those prepared with specific tannin-enhancing procedures, such as gall boiling, were located and used in the discrimination basis.

Uncovering the Terahertz Spectrum of Copper Sulfate Pentahydrate

Terahertz vibrational spectroscopy has evolved into a powerful tool for the detection and characterization of transition metal sulfate compounds, specifically for its ability to differentiate between various hydrated forms with high specificity. Copper(II) sulfate is one such system where multiple crystalline hydrates have had their terahertz spectra fully assigned, and the unique spectral fingerprints of the forms allows for characterization of multicomponent systems with relative ease. Yet the most commonly occurring form, copper(II) sulfate pentahydrate (CuSO4·5H2O), has proven elusive due to the presence of a broad absorption across much of the terahertz region, making the unambiguous identification of its spectral signature difficult. Here, it is shown that the sub-100 cm(-1) spectrum of CuSO4·5H2O is obscured by absorption from adsorbed water and that controlled drying reveals sharp underlying features. The crystalline composition of the samples was monitored in parallel by X-ray diffraction as a function of drying time, supporting the spectroscopic results. Finally, the terahertz spectrum of CuSO4·5H2O was fully assigned using solid-state density functional theory simulations, helping attribute the additional absorptions that appear after excessive drying to formation of CuSO4·3H2O.

The role of terahertz polariton absorption in the characterization of crystalline iron sulfate hydrates

Solid-state density functional theory indicates that polariton absorption plays a central role in understanding the identifying terahertz-frequency spectral features of hydrated iron sulfate compounds.

Distribution of Acidity and Alkalinity on Degraded Manuscripts Containing Iron Gall Ink

Long-time preservation of manuscripts depends on the stability of their support. One of the most important degradation processes of paper manuscripts containing iron gall ink is the acid hydrolysis of cellulose. The heterogeneity of the distribution of their constituent materials, together with the defined position of ink as a source of degradation agents, makes it difficult to obtain reliable and detailed information about degradation processes. The aim of this study is to contribute to the knowledge of the acid degradation process by looking at the distribution of relevant variables (pH, acidity and alkaline reserve) on real untreated iron gall ink containing manuscripts at different degradation stages. The study discusses the well-known differences between surface and cold extraction pH determination. It corroborates the relationship between pH, acidity and alkalinity and degradation stages, pointing out that acidity values for some manuscripts in apparent good condition are not far from those obtained for degraded manuscripts. The results indicate that in some partially degraded manuscripts, the coexistence of acid areas and areas with an alkaline reserve which do not participate in the neutralization process is possible. The role of water as a solvent for this equilibrium has also been evaluated.

Production and validation of model iron-tannate dyed textiles for use as historic textile substitutes in stabilisation treatment studies

BACKGROUND

For millennia, iron-tannate dyes have been used to colour ceremonial and domestic objects shades of black, grey, or brown. Surviving iron-tannate dyed objects are part of our cultural heritage but their existence is threatened by the dye itself which can accelerate oxidation and acid hydrolysis of the substrate. This causes many iron-tannate dyed textiles to discolour and decrease in tensile strength and flexibility at a faster rate than equivalent undyed textiles. The current lack of suitable stabilisation treatments means that many historic iron-tannate dyed objects are rapidly crumbling to dust with the knowledge and value they hold being lost forever.This paper describes the production, characterisation, and validation of model iron-tannate dyed textiles as substitutes for historic iron-tannate dyed textiles in the development of stabilisation treatments. Spectrophotometry, surface pH, tensile testing, SEM-EDX, and XRF have been used to characterise the model textiles.

RESULTS

On application to textiles, the model dyes imparted mid to dark blue-grey colouration, an immediate tensile strength loss of the textiles and an increase in surface acidity. The dyes introduced significant quantities of iron into the textiles which was distributed in the exterior and interior of the cotton, abaca, and silk fibres but only in the exterior of the wool fibres. As seen with historic iron-tannate dyed objects, the dyed cotton, abaca, and silk textiles lost tensile strength faster and more significantly than undyed equivalents during accelerated thermal ageing and all of the dyed model textiles, most notably the cotton, discoloured more than the undyed equivalents on ageing.

CONCLUSIONS

The abaca, cotton, and silk model textiles are judged to be suitable for use as substitutes for cultural heritage materials in the testing of stabilisation treatments.

Investigation of the composition of historical and modern Italian papers by energy dispersive X-ray fluorescence (EDXRF), X-ray diffraction (XRD), and scanning electron microscopy energy dispersive spectrometry (SEM-EDS)

In this work, a study concerning the composition of Italian papers from the seventeenth to the twentieth centuries was carried out using energy dispersive X-ray fluorescence spectrometry (EDXRF), X-ray diffraction (XRD), and scanning electron microscopy coupled to energy dispersive spectrometry (SEM-EDS). The analyzed samples consisted of papers employed for drawing, writing, printing, and absorbance. Observations carried out by SEM magnified the typical paper morphology. EDXRF in combination with XRD and SEM-EDS allowed the determination of calcite, gypsum, kaolin, talc, magnesite, and dolomite, used as fillers in the production of the papers studied herein. The inks present in the handwritten and printed papers, investigated by SEM-EDS and μ-EDXRF, were synthetic, Fe based, and iron gall inks.

Raman microscopy and x-ray fluorescence analysis of pigments on medieval and Renaissance Italian manuscript cuttings

Italian medieval and Renaissance manuscript cuttings and miniatures from the Victoria and Albert Museum were analyzed by Raman microscopy to compile a database of pigments used in different periods and different Italian regions. The palette identified in most manuscripts and cuttings was found to include lead white, gypsum, azurite, lazurite, indigo, malachite, vermilion, red lead, lead tin yellow (I), goethite, carbon, and iron gall ink. A few of the miniatures, such as the historiated capital "M" painted by Gerolamo da Cremona and the Petrarca manuscript by Bartolomeo Sanvito, are of exceptional quality and were analyzed extensively; some contained unusual materials. The widespread usage of iron oxides such as goethite and hematite as minor components of mixtures with azurite is particularly notable. The use of a needle-shaped form of iron gall ink as a pigment rather than a writing material was established by both Raman microscopy and x-ray fluorescence spectroscopy for the Madonna and Child by Franco de' Russi.

Can electrospray ionization help the characterization of iron gall inks? Investigation on the interactions of gallic acid with iron ions in aqueous solutions

In the present work, an investigation has been conducted by electrospray ionization (ESI) experiments to characterize the structures of iron gall ink complexes in solution. Simple mono and polyphenolic acid molecules added to iron sulfate salts were chosen to model the recipes of ink composition. Theoretical calculations have been used (1) to determine the stability of the ionic complexes generated in the gas phase, (2) to explain which structures are more likely generated in the electrospray ion source, and (3) to determine which mechanisms are likely involved in their formation. Fragmentation pathways of the derived structures have also been investigated and rationalized to facilitate the interpretation of the data obtained under collisionally induced dissociation (CID) conditions.The present study confirms the assumption that ESI experiments with ions that are preformed in solution must be considered carefully. As a matter of fact, the study of ion formation mechanisms in the ion source is necessary to establish relationships between the ion structures in the condensed phase and the gas phase.

Interactions in iron gall inks

Simple iron gall inks composed of gallic acid, ferrous sulfate, and gum arabic and in some cases also of copper(II) sulfate were prepared. The process of iron ion complex formation with gallic acid was investigated using UV-VIS spectroscopy, pH measurements, and by monitoring the concentration changes of Fe(II) ions. The admixture of Fe(II) ions to gallic acid induced a bathochromic shift of absorption bands at 215 nm and 265 nm in the UV-VIS spectra. Formation of a new absorbance band in the visible area was also observed and used to calculate the initial rate of complex formation. Concurrently, the pH values and the concentration of Fe(II) ions in the solution decreased. Gum arabic significantly enhanced the complex formation and its stability. On the contrary, the addition of Cu(II) ions to the solution decelerated the complex formation considerably.

Optical Coherence Tomography for Examination of Parchment Degradation

A novel application of Optical Coherence Tomography utilizing infrared light of 830 nm central wavelength for non invasive examination of the structure of parchment, some covered with iron gall ink, is presented. It is shown that both the parchment and the ink applied are sufficiently transparent to light of this wavelength. In the study, Spectral OCT (SOCT) as well as Polarisation Sensitive OCT (PS-OCT) techniques were used to obtain cross-sectional images of samples of parchment based on scattering properties. The second technique was additionally employed to recover the birefringence properties and the optical axis orientations of the sample. It was shown that freshly produced parchment exhibits a degree of birefringence. However, this property declines with ageing, and samples of old parchment completely depolarise the incident light.