In Search of Scientific Methods for Conservation of Historic Silk Costumes

Abstract: The general aim of this dissertation is to lay ground for the evaluation of conservation methods for historic costumes. The Royal Armoury, Stockholm has a large number of 17th century men’s garments, many of them made of silk and in need of conservation. Knowledge of the advantages and disadvantages of methods used in textile conservation is of vital importance for the preservation of historic textiles. The work has been presented in three papers. Paper I presents the documentation and preservation of 55 very degraded silk fragments from Queen Kristina’s burial costume. Analyses were performed with FT-IR diffuse reflection measurements (DRIFTS). A nitrogen filled case was used to preserve the fragments. Two of the aims of Paper II were to find mechanical test methods that can simulate “museum handling” and to determine the most common conservation methods. Samples of standard fabric of both silk and wool were aged and treated with the most common conservation method. The samples were then exposed to mechanical tests simulating museum handling. Abrasion and rupture strength tests turned out to be promising methods to simulate handling. Paper III aimed at finding an optimal accelerated ageing procedure, simulating as far as possible the nature of degradation found in naturally aged silk from the seventeenth century. After exposure to different environmental conditions standard silk samples were compared to samples of seventeenth century silk material using analytical markers assessed by ATR-FTIR, SEC and tensile tests. Thermo-oxidation in dry air at 125°C for 28-56 days results in a silk most similar to the samples of the historic costumes.