模拟古代丝织品上天然染料剥色研究

摘要

Extraction is the first step of dye analysis on ancient textiles.The methods and reagents to extract dyes from silk were studied.Nine commonly used ancient plants dyes were chosen to dye modern silk samples following ancient procedures.The selected dye sources were Caesalpinia sappan,Rubia cordifolia,Lithospermum erythrorhizon,Gardenia jasminoides,Sophora japonica,Curcuma longa,Phellodendron amurense,gallnut,shell of chestnut and indigo.Extraction solvents tested include DMF,acetic acid,methanol,ethanol,acetone,ethyl acetate,petroleum ether,sodium bicarbonate solution（pH=10）,HCl/methanol/H2O（v/v/v=2：1：1）,3M HCl/ethyl acetate（v/v=1：1） and 10% sulfuric acid/methanol（v/v=1：1）.Furthermore,the dyed silk samples were aged and extracted to compare these extracts with extracts of un-aged silk samples.Results showed that HCl/methanol,DMF,and acetic acid did well in extraction.However,HCl/methanol hydrolyzed the silk fiber greatly.Caesalpinia sappan,Rubia cordifolia,Lithospermum erythrorhizon,Gardenia jasminoides,Curcuma longa and Phellodendron amurense dyed silk samples could be extracted using methanol,10% sulfuric acid/ethyl acetate and 2% sodium bicarbonate solution.Curcuma longa and Phellodendron amurense dyed samples could also be extracted using ethanol and water.Dyes with mordant could be extracted using EDTA/DMF,which did little damage to silk.Gallnut and shell of chestnut dyed silk could be extracted by water or 70% ethanol.Indigo could be extracted by pyridine,pyridine/water,DMF and acetic acid.The dyes on heat-aged silk had undergone some oxidation and cross-linking processes,thus the extraction was more difficult.In case a reagent does not meet particular analytical needs,the methods of evaporation-redissolution or extraction could be used.%剥色是古代纺织品染料分析的第一步。如何选择合适的剥色方法和试剂是做好染料分析研究的基础。为此,本研究在已有研究的基础上,以模拟古代染色样品及其老化样品为对象,对染料剥色方法和试剂进行了实验研究。本研究采用古代常用的九种植物染料苏木、茜草、紫草、栀子、槐花、姜黄、黄柏、五倍子/栗壳靛蓝对现代丝绸用古代方法模拟染色。选取DMF、乙酸、甲醇、乙醇、丙酮、乙酸乙酯、石油醚、2%碳酸氢钠（pH=10）、盐酸/甲醇/水（2：1：1）（括号中为体积比,下同）、3M盐酸/甲醇（1：1）和10%硫酸/乙酸乙酯（1：1）等溶剂对各种染色丝绸进行剥色实验。此外,对染色后的丝绸进行老化,并将其与未老化的样品做剥色对比研究。结果表明,盐酸/甲醇/水、DMF、乙酸的剥色效果好,但盐酸/甲醇/水体系丝纤维水解严重。苏木、茜草、紫草、栀子、姜黄、黄柏染色丝绸用甲醇/水、10%硫酸/乙酸乙酯、2%碳酸氢钠剥色均有一定效果,姜黄和黄柏染色丝绸也可以用乙醇和水剥色。媒染染色丝绸用EDTA/DMF的无损方法剥色效果好。五倍子和栗壳丝绸用水或70%乙醇剥色效果好,靛蓝丝绸用吡啶、吡啶/水、DMF、乙酸剥色效果好。热老化丝绸上色素发生了一定程度的氧化和交联作用,剥色效果不如未老化的纤维。如果剥色试剂不符合后续分析的要求可以用蒸干重新溶解或者萃取的方法。