A new quantitative method: non‐destructive study by Raman spectroscopy of dyes fixed on wool fibres

Raman spectroscopy was employed for the quantitative analysis of mixtures of the three dyes used at the Manufacture Nationale des Gobelins (Paris, France), fixed on wool fibres. It is based on a laboratory‐written program that implements the decomposition of the combined Raman spectrum into the relative contributions of the spectra of each constituent. To perfect the method, it was first applied to fibres dyed at the laboratory and then extended to the dyeing baths, before and after the dyeing process. Binary and ternary mixtures, in which the quantities were known, were used. The percentages obtained by applying the quantitative analysis of the Raman spectra were similar to those introduced. The method therefore allows quantification of the dyes and gives information about the dyeing process. Fibres recently dyed at the workshop of the Manufacture Nationale des Gobelins with unknown proportions were analysed using this method. The results obtained are in conformity with the observed colour of the dyed hanks of wool.