A vibrational approach for the study of historical weighted and dyed silks

• The present work is focused into obtain vibrational information of historical silk samples.
• The effects that the degumming and weighting processes have on the degradation of silk are inferred.
• The Raman data suggests that crystalline portions of silk are unaffected in historic samples.
• Spectral results indicate the presence of Prussian blue and Sudan Black B in samples dated from late 19th to early 20th century.

Samples from six different historic silk objects were studied with the Raman and ATR-IR vibrational techniques. A set of degummed and weighted silks was prepared in order to recognize the vibrational signature associated with the processes used. The spectral information allowed the identification of the weighting process and the dyes used in some of the cases. The different spectra also allowed infer about the deterioration observed in the samples. The silk fibroin displays slight conformational modifications by the weighting process. The degumming process seems to have no chemical effect on the fibroin stability.