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Abstract Books, prints, drawings, watercolours, engravings, as well as all other works of art based on paper, are very susceptible to fungal development. The excreted substances and the fungal structures themselves are often coloured and interfere with the readability of the artefacts, diminishing their artistic and monetary value. In order to direct cleaning methods for specific fungal stains on paper, the colourants (molecules) responsible for those stains need to be assessed. However, the literature regarding fungal stains on paper and colourants produced by those fungi is very dispersed and scarce. Therefore, the main objectives of this work were surveying the most common stains on paper, the colourants present on those stains and the main fungi responsible for these colourants' production. To achieve these goals, two different but complementary literature reviews were made: one on paper conservation literature, where fungal stains observed on paper cultural heritage are reported; and another survey on the chemical/food/pharmaceutical fields where colourants' molecules produced by fungi, that can colonise paper cultural heritage, are identified and studied in greater detail. This paper presents the first literature review on this subject. The results show that the fungal genera more frequently related with fungal stains on paper cultural heritage are Aspergillus (29%) and Penicillium (13%). The most common colour of the stains is brown (54%), caused by foxing in most of the cases. However, in the paper conservation literature, no consistent correlation has been observed between stain colour on paper/specific fungal species and colourants/chemical compounds. On the literature review regarding the use of fungal colourants for industrial/commercial purposes, the referred colourants can be mostly classified chemically as carotenoids and polyketides. Biosynthetically, most colourants produced by fungi are polyketide-based and representative classes may include chemical structures such as azaphilones, anthraquinones, hydroxyanthraquinones, naphthoquinones and other structures. From a total of 80 different colourants, the ones mostly produced by paper colonising fungi were polyketide quinones, namely the hydroxyanthraquinoid (HAQN) colourants. This review showed that the most commonly studied colours are yellow and red, followed by orange. The production of these colourants is often associated with the genera Aspergillus sp. and Penicillium sp. which are frequently found on stained paper. Overall, there is no doubt that colourants producing fungi are a serious problem to paper conservators, since there is a great variety of colourants produced by different species of fungi colonising paper. This review catalogues the fungal genera, species and excreted colourants mentioned in the literature as being responsible for staining paper cultural heritage. [ABSTRACT FROM AUTHOR]

Historic works on paper, illuminated (painted) or unpainted manuscripts, and textiles are fragile and nearly impossible to sample. Non-invasive techniques such as visible microscopy, X-ray fluorescence, Raman, and reflectance spectroscopy are commonly used to determine the artist material present. Recently, nonlinear optical ultrafast pump-probe microscopy was shown to provide non-invasive, high-resolution mapping of pigments in historic paintings to investigate paint stratigraphy. In this paper, we combine our pump-probe contrast with nonlinear fluorescence and second-harmonic generation contrasts exhibited by fibrous supports composed of natural bio-materials (cellulose, collagen, or lignin). Hence, our multi-modal nonlinear microscope is able to simultaneously investigate pigments in conjunction with their support in three dimensions with micrometer-scale spatial resolution. Here we examine the utility of nonlinear pump-probe microscopy by studying a series of mock-up samples, including indigo-dyed cotton cloth, ultramarine blue painted on various types of paper, and papers painted with mixtures and layers of the two pigments. In each case we find that we can combine pump-probe pigment contrast with nonlinear optical fiber contrast to obtain spatial information that is otherwise unavailable to the conservator. [ABSTRACT FROM AUTHOR]

Abstract: The goal of preventive conservation is to provide the correct maintenance of our cultural heritage in order to enrich our future. The Canadian Museum of Nature developed a risk model for preventive conservation that has proven useful in application to a Portuguese archive. This work applies this model to compare the magnitudes of specific risks estimated for this same archive collection when located in either of two pairs of storage rooms. These rooms are in two different parts of this building: two are in an older part and two are in a recent addition. It was, therefore, necessary to assess the building itself, both structurally and environmentally, as well as analyse its common human practices. In terms of the overall risk magnitude, the best room was found to be in the recent building and the worst in the older building. However, risks related to water problems were found to be higher in the new building. In this work cost-free measures and easy to implement recommendations are given in order to improve the quality of the storage rooms. A final comment on the method itself is also given. [Copyright &y& Elsevier]