摘要
Silks are among the most precious ancient and historic artefacts worldwide. While washing removes the natural gum from the fibres during the fabrication of most silk textiles, for a small proportion of historic silks some or perhaps all of the sericin still remains. This paper investigated the effect of sericin coating on the aging of silk fibroin by means of ATR and tensile testing. The results show that sericin can provide some extent of protection from light and heat aging. However, in high humidity environments degummed and ungummed silk aged at the same rate because of leaching of sericin. Silk degraded at faster rate and more extensively in a moist environment. ATR could give very useful information about the aging of silk. The ATR-derived crystallinity index is good at tracing the aging factor and extent of silk deterioration. Alanine and tyrosine within fibroin, as estimated by ATR spectroscopy, are very sensitive to light, but not to heat and water. The ATR absorbance intensity ratio Iamide Ⅲ/ Iamide I is very useful for deterioration evaluation of archaeological silk objects. As a high humidity resulted in the leaching of silk, it is suggested for sericin-coated silk in collections, that not only wet cleaning is harmful, but also that storage or display in a high RH environment would be detrimental.
Silks are among the most precious ancient and historic artefacts worldwide. While washing removes the natural gum from the fibres during the fabrication of most silk textiles, for a small proportion of historic silks some or perhaps all of the sericin still remains. This paper investigated the effect of sericin coating on the aging of silk fibroin by means of ATR and tensile testing. The results show that sericin can provide some extent of protection from light and heat aging. However, in high humidity environments degummed and ungummed silk aged at the same rate because of leaching of sericin. Silk degraded at faster rate and more extensively in a moist environment. ATR could give very useful information about the aging of silk. The ATR-derived crystallinity index is good at tracing the aging factor and extent of silk deterioration. Alanine and tyrosine within fibroin, as estimated by ATR spectroscopy, are very sensitive to light, but not to heat and water. The ATR absorbance intensity ratio Iamide Ⅲ/ Iamide I is very useful for deterioration evaluation of archaeological silk objects. As a high humidity resulted in the leaching of silk, it is suggested for sericin-coated silk in collections, that not only wet cleaning is harmful, but also that storage or display in a high RH environment would be detrimental.
