Removal of natural organic dyes from wool–implications for ancient textile provenance studies

An assessment of procedures to remove exogenous Sr before 87Sr/86Sr analysis of wet archaeological wool textiles

“…It has previously been suggested that the 87 Sr/ 86 Sr composition of the leachate from the cleaning procedure with HF(aq) with a strong oxidising agent represents the contribution from the dyestuff and therefore, the origin of this material (Frei et al, 2010). Results from this study do not support this conclusion, at least for madder-dyeing/alum-mordanting.…”

“…Sr isotope provenancing has proved exceptionally useful to discriminate local from non-local in human and animal archaeological remains (Bentley, 2006;Chenery et al, 2010;Viner et al, 2010), in modern human forensic studies (Aggarwal et al, 2008, Font et al, 2012 and in ecological studies (Ben-David and Flaherty, 2012;Hobson, 1999) including in modern bird feather keratins (Evans and Bullman, 2009;Font et al, 2007;Sellick et al, 2009). The technique has been extended to finds of archaeological wool textiles (Frei et al, 2009a, Frei, et al, 2009b, Frei, et al, 2010, von Carnap-Bornheim et al, 2007. These studies did not, however, directly test the effect of diagenesis under soil burial conditions, a process which is known to overprint the Sr isotope signature in bone on archaeological timescales (e.g.…”

“…It compares the effects of four methods employed for cleaning keratin fibres for Sr isotope analysis: high pressure N 2 (Font et al, 2007); 20% HF(aq) (Frei et al, 2009b), with and without the addition of ammonium persulfate, a strong oxidising agent (Frei et al, 2010); and a methanol/ dichloromethane mixture and water (preparation procedure for light stable isotope analysis; adapted from Hedges et al, 2005). We hypothesised that if endogenous Sr in wool binds primarily to:…”

Bronze Age wool: provenance and dye investigations of Danish textiles

“…cross-disciplinary analytical methodologies has made a particularly important contribution. These include: the refinement of wool fibre identifications; different chemical extraction methods for the identification of organic dyestuffs; and new developments in the fields of aDNA and strontium isotope analysis (Benson et al 2006;Frei et al 2009Frei et al , 2010Vanden Berghe et al 2009;Brandt et al 2011;Gleba 2012;Rast-Eicher & Bender Jørgensen 2013;Frei 2014).…”

Hydrofluoric acid pre-treatment of matte artists’ paints for binding medium analysis by Fourier transform infrared microspectroscopy

“…Many cultural heritage laboratories are already using HF as a hydrolysis reagent for surface enhanced Raman scattering studies [12] or for the extraction of dyes from textiles and paintings for high pressure liquid chromatography analysis [13][14][15]. The reagent has also occasionally found use in conservation studios for cleaning rust-stained objects [16], soiled architectural surfaces [17], and archaeological textiles [18]. Although the use of reactive fluoride to remove spectral interferences from artists' paint samples prior to FTIR analysis has been mentioned in the literature [19,20], the only published work on fluoride treatment of paints uses a 24 hour reaction of paint samples with gaseous sulfur tetrafluoride (SF4) in a specialized reaction vessel in order to selectively derivatize certain carbonyl species in oil media [21].…”