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Black-dyed artefacts are found in museums worldwide, many produced using an irontannate compound. Deterioration of iron-tannate dyed artefacts is an international preservation issue: in New Zealand the deterioration of paru (iron-tannate) dyed Māori textiles is widespread. This article reports experimental work testing the efficacy of sodium alginate, a consolidant developed for deteriorated paru-dyed muka (fibre from harakeke; Phormium tenax). The colour stability, strength retention, and acidity of paru-dyed muka consolidated with sodium alginate (0.25, 0.5, and 1% w/v in water) was tested pre- and post-artificial light ageing. This study found that sodium alginate had no negative effect on paru-dyed muka and in some cases provided benefit. Interestingly, the colour of parudyed muka is substantially more stable in UV-filtered light than previously recognised. Also microfading results were in agreement with visual assessments of colour change at 1 Mlux hour exposure, providing confidence in this relatively new technique to assess colour change. [ABSTRACT FROM AUTHOR]

The derivatising agentm-(trifluoromethyl)phenyltrimethylammonium hydroxide (TMTFTH) has been employed for more than a decade at the Canadian Conservation Institute (CCI) to extract natural dyes from historical textiles and other dyed substrates. The alkaline reagent breaks the bonds between the colourants and the mordant ions or functional groups of the substrate, releasing the dye compounds into the extraction solution, and derivatises polar functionalities to produce compounds that are amenable to subsequent analysis by gas chromatography–mass spectrometry (GC–MS). This approach allows for the identification of the colourants, and is also useful in determining the presence of degradation products from the dyes and substrates, non-dye marker compounds, auxiliary compounds added to the dye bath, and substances present on the object through anthropogenic use, conservation treatments, or possible pesticide contamination. This paper discusses compounds formed through the reactions of TMTFTH with flavonoid dyes (dyer’s buckthorn, old fustic, weld, red sandalwood, and brazilwood), quinone dyes (madder,Relbunium,Galium, cochineal, lac, and walnut), indigoid dyes (indigo, Tyrian purple, and indigo carmine), turmeric, marigold, lupin and several lichen species. Results from a selection of historical dyed textiles and other decorative objects analysed at the CCI are provided to illustrate applications of the methodology. [ABSTRACT FROM AUTHOR]

Despite substantial literature on the dyeing of textiles, there is a lack of research about colouring Japanese mending papers (tissue papers) used for paper conservation purposes. This study investigates the fungal bioreceptivity of Japanese tissue papers after they have been treated with various dyes and pigments. A variety of toning materials including plant dyes, watercolours, acrylic paints, inks, pastels, gouaches, and colour pencils are commonly used by conservators for paper toning purposes. In this study, two Japanese tissue papers (Yukyu-shiandSekishu Mare) were treated with selected plant dyes, watercolours, and acrylic paints and then inoculated with fungal species. Quantitative real-time polymerase chain reaction (qPCR) was used to quantify the DNA fromAspergillus nigerandPenicillium rubrumas a proxy for fungal species abundance before and after inoculation and artificial moist heat ageing. qPCR primers which were universal for fungi amplified DNA from papers inoculated withA. nigerandP. rubrumand these species were found to grow less on treatedSekishu MareandYukyu-shipapers compared with untreated papers.Sekishu Marepapers treated with artists' acrylic paints were found to be more resistant to fungal growth than similarly treatedYukyu-shipapers. This study suggests that for the best long-term preservation outcomes for paper materials in archives, libraries, galleries, and museums, acrylic paints generally perform better in conservation terms than most plant dyes and watercolours, although most colourants displayed some bioinhibition. [ABSTRACT FROM PUBLISHER]

Shosoin textiles, handed down from the eighth century in Nara, Japan, have entranced many people with their beautiful colors made from natural dyes. Dye analysis of the Shosoin textiles, including the red carpet laid inside the workshop hall at the Todaiji Temple in Nara, used for the inauguration of the statue of the Great Buddha in the temple in 752 AD; a red undergarment and a gown with a tie-dyed design worn by craftsmen in the Todaiji Temple; and embroidered shoes belonging to Empress Komyo (701-760 AD), were conducted by excitation-emission matrix fluorescence spectrometry equipped with a fiber optics probe. Comparison of the spectra to references identified safflower red ( Carthamus tinctorius L.) in the red or orange areas on these original textiles. The spectrometry of the gown and the shoes offered the identification not only of safflower red but also of amur cork tree. This study finds these examples to be the oldest scientifically confirmed presence of safflower red on historic textiles at present. [ABSTRACT FROM AUTHOR]

The history, analysis, and use of the semi-synthetic dye indigo carmine is described by means of a study of historical sources including patents, dye identification using high performance liquid chromatography (HPLC), and the examination of dyed textiles. Indigo carmine, the acid dye 'Saxon Blue', was invented by Johann Christian Barth in 1743. Indigo carmine is a water-soluble blue acid dye with the advantage of an easy dyeing process. Its disadvantages are poor lightfastness and washfastness. For the identification of indigo carmine by HPLC, a gradient using water, methanol, and 0.5 mM tertiary butyl ammonium hydroxide can be used to give an unambiguous analytical result. Analyses of dated textile objects prove that indigo carmine was in use after 1770 until the beginning of the twentieth century. This study provides practising conservators with chemical, technological, and historical information which can help in the identification of textiles dyed with indigo carmine, and suggests ways of responding to poor washfastness. [ABSTRACT FROM AUTHOR]

The aim of this literature review is to provide a broad introduction to the little-researched subject of early synthetic organic dyestuffs and their use on historic textiles. Early synthetic organic dyes are briefly described, as is the relevant terminology. A brief history of the development of synthetic dyes up to 1901 is given, followed by a discussion of the problems arising from their use in the nineteenth century. Conservation issues relating to early synthetic dyes addressed in the literature from 1950 to 2003 are cited. The extent of use on historic textiles is described. The role of dye analysis in the study of early synthetic organic dyestuffs is indicated, with examples to illustrate its importance. A table of the 22 most commonly used early synthetic dyes is provided with International Colour Index numbers. [ABSTRACT FROM AUTHOR]

The quantitative determination of selected dyestuff components by high performance liquid chromatography, diode-array detection and post-run data manipulation was used to recognize dyes on historic yarns prepared from Dactylopius coccus (American cochineal), Kermes vermilio (kermes), Porphyrophora polonica (Polish cochineal), Por- phyrophora hamelii (Ararat cochineal) or Kerria lacca (Indian lac). Study of scale-insect red dyes suggests a rather widespread use of mixed primary sources, not only of insect reds alone but also in combination with plant reds and tannins. [ABSTRACT FROM AUTHOR]

This paper describes the identification of natural dyes in historic textiles from the mid nine- teenth century using thin layer chromatography (TLC) and microchemical tests. Yellow, brown and red dyes were analyzed by TLC and blue by microchemical tests. Seventy samples which were taken from museum textiles were compared with reference materials prepared in the Laboratory as well as with chemically pure major dye components of natural dyes. One yellow, two brown, one blue and two red natural dyes were identified in different primary and secondary coloured samples. It is also seen from the results that mixtures of two dyes have been used to obtain desired shades. [ABSTRACT FROM AUTHOR]

The fading rate curves of selected natural dyes were constructed from color difference measurements made using a tristimulus colorimeter. Examination of the curves showed that most natural dyes fade rapidly initially followed by a slower rate of fading. Only the most lightfast natural dyes fade at a constant rate over time. The implications of these findings for museum textiles are discussed. [ABSTRACT FROM AUTHOR]

Separation and quantitative determination of anthraquinones is achieved by high performance liquid chromatography in mixtures of methanol, water and formic acid on a reversed-phase stationary phase. The products are identified by retention time and, more accurately, by standard additions and UV-visible spectroscopy. This methodology has been applied to extracts of plant roots and insects, commonly used in earlier times as the source of red dyestuffs for dyeing textiles. Quantitative evaluation of the anthraquinone derivatives present in ancient red dyes was carried out after acid hydrolysis of 0.2 to 2.0mg of textile fibre. Due to the great sensitivity of the method, important minor constituents, such as kermesic acid in cochineal, can be detected. [ABSTRACT FROM AUTHOR]

Some of the dyes that may have been used in Anglo-Scandinavian York are listed. Procedures for extracting dyes from textile samples are described. Identification of dyes is based on comparison of the visible spectrum with those of known dyes. Addition of magnesium acetate to a solution in methanol of many of the mordant dyes causes a characteristic change in the absorption spectrum which enhances the sensitivity of the detection, and can be used to strengthen the identification of the dye. Because of spectroscopic interference from staining extracted from the textile along with the dye, yellow dyes cannot be reliably identified without separation of dye from dirt. The extraction procedures described are not, in general, applicable to lichen dyes. Of over 90 Anglo-Scandinavian textile samples investigated, over one half show evidence of having been dyed, and on about one quarter of the samples, madder and indigotin were positively identified. The madder was Rubia tinctorum L. Yellow dyes, and probably most lichen dyes, would not have been detected. [ABSTRACT FROM AUTHOR]

Remnant dye on an excavated textile has been identified using a Fourier transform infrared microscope on a scale far below that which is possible by extractive techniques. The sample requires minimal preparation, a single fibre being sufficient to obtain a useful signal. A spectral data library of fibre, dyes and mordants has been built into the computer analysis program and four separate algorithms within the search facility are used to make the identification. The method is quick and may avoid some of the problems caused by masking of the infrared signal due to sample contamination during burial. [ABSTRACT FROM AUTHOR]