Characterisation of foxing stains in eighteenth to nineteenth century drawings using non-destructive techniques

Abstract

The reddish-brown, brown or yellowish stains of circular or irregular shape known as foxing spots have been fully described in conservation literature but still, this phenomenon does not find any scientific agreement since many hypotheses have been raised concerning their origin. In this work a contribution to foxing definition not only focussed on its appearance but also reported on its chemical information. For this purpose foxing stains present in drawings from two Portuguese artists dated from the eighteenth to nineteenth centuries were observed under ultra-violet light and optical microscope and analysed by three non-invasive spectroscopy techniques. The observations carried out on the stains provided information on their surface morphology. The use of energy-dispersive X-ray fluorescence revealed a variation on the elemental content between foxing and paper region. Although the results from X-ray diffraction analysis showed no signs of cellulose degradation in foxing stains, Fourier-transformed infrared analysis revealed the presence of oxide groups. Both the information on the chemical nature and surface morphology of the stains achieved in this study will contribute to increase foxing formation information and develop future protocols for conservation purposes.

Raman analysis assessed by Fourier‐Transformed infrared and X‐ray fluorescence spectroscopies: a multi‐analytical approach of ancient chromolithographs from the 19th century

“…Furthermore, material characterization of works on paper can supply helpful information to develop conservation strategies. Good examples of the importance of these studies are the increasing number of references available in the literature in the last few years …”

Mining the Material Archive: Balancing Sensate Experience and Sense-Making in Digitized Print Collections

“…Close-up raking light imaging has the added benefit of not requiring any other additional equipment than is routinely employed in digitization. Another approach to be considered would be employing microscopic imaging in raking light (such as was used, for example, in a study of 'foxing' or the 'small, roundish spot stains of reddish or yellowish brown colour' in eighteenth-and nineteenth-century drawings (Manso et al, 2009(Manso et al, : 2029) to accentuate texture even further, though this does involve more specialized equipment. Using close-up raking light imaging we have started to explore how to showcase visually the tactile differences between paper types (see Figure 4 for examples).…”

Contribution to the characterization of foxing stains on printed books using infrared spectroscopy and scanning electron microscopy energy dispersive spectrometry

“…The advantage of this technique is its capacity to investigate directly samples without preparation. Some authors have already used FTIR analyses to study the foxing phenomenon and highlighted the presence of oxide groups (Bicchieri et al, 2002;Buzio et al, 2004;Manso et al, 2009). The scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) analysis was used for comparative elemental composition assessment of papers inside and outside the foxing stains.…”