British Columbia had an influx of Chinese immigrants in the mid- to late-19th Century, attracted by both the gold rush and contracts to work on the Canadian Pacific Railway. With them on their journey across the Pacific Ocean, the immigrants brought a few treasured possessions from their old home, including garments made of a unique textile known as ‘mud-silk’.
Mud-silk is a textile produced in Southeast China and other areas of Southeast Asia, characterised by a glossy black face and a matte orange-brown reverse (Figure 1). The fabric has a thin, dark, resin-like film on its surface which has water resistant properties (Figure 2); this, combined with its crisp, cool handle, makes it comfortable to wear in the sticky, warm climes of Southeast Asia.
Mud-silk’s surface film and name are derived from the dyeing and finishing process, which involves spreading iron-rich river mud on silk dyed with an extract from the ju-liang root (Dioscoria rhipogonioides) and baking it in the long, hot summer sun for several days. A chemical reaction between the iron in the mud and tannins in the dye occurs in excess dye on the textile’s surface, changing the surface colour from orange-brown to black. After the mud is washed off, a finish is applied to make the now black film of excess dye glossy. Since the mud is only applied to one side of the silk, the reverse side remains orange-brown from the ju-liang root dye.
As part of a textile conservation summer internship in 2012, I investigated a collection of 22 mud-silk garments at the Royal BC Museum, dated to between 1890 and 1920 – the end of the first Chinese immigration boom in BC The garments had been donated to the Museum in 2004 after their owners in Victoria’s Chinese community passed away, and consisted of Chinese-style trousers, waistcoats and jackets. Following recent research1 the Museum realised that this collection of garments may have been more significant than they first thought. Through my investigation I confirmed that the garments were mud-silk, and provided information regarding their fibre content, quality and construction. While examining the garments, I noticed that one particular jacket had an unusual flaking problem, resulting in tiny black fragments of the surface film detaching from the textile and shedding whenever it was moved (Figure 3).
As a conservator, my aim is to make objects more stable so that they can be displayed and studied, and this can be done through passive or active means. Museums aim to control the environment objects are stored and displayed in, as this can prevent damage from pests and pollutants, and also slow down the inevitable chemical breakdown that everything must eventually give in to (see Colleen Wilson’s article ‘Same As It Ever Was’). However sometimes objects are physically damaged or weak, so that they can’t be displayed or studied without causing even more damage. In these cases, conservators often intervene to strengthen areas at risk of being lost and prevent further damage from occurring. Sometimes conservators also aim to improve the visual appearance of an object, to allow it to be better viewed as a whole or to preserve its artistic integrity.
The flaking condition of the mud-silk jacket at the Royal BC Museum made the garment particularly inaccessible, as it could not be touched or moved without causing more flakes to detach. Because of this I decided to research how to stabilise a flaky surface film on mud-silk, to prevent flakes detaching and allow research and display of such textiles. Similar treatments are routinely carried out on paintings, and less routinely on painted textiles, so I used published accounts of these as a starting point. The treatment is called ‘consolidation’ and requires the use of a very dilute adhesive, usually dissolved in water or alcohol. The adhesive is applied to the surface of the flaky film with a brush or aerosol applicator, and is absorbed between the cracks and pores of the film, sticking the loose flakes back down to the textile and strengthening the brittle film. However, the adhesive used can often cause the textile to stiffen. This is not such a problem with paintings and flat textiles, as they will stay flat and not need to flex very much; however with garments it can change the way that they drape and move, altering the silhouette. This can be a problem for historical interpretation of clothing, as textile historians often look at the silhouette of a garment to give them information about the era in which it was made and worn. Because of this, I wanted to find a consolidation treatment that would stabilise a flaky surface film without noticeably stiffening the textile.
Since I couldn’t carry out testing on an actual historical garment, I created samples similar to the flaky mud-silk by painting a similar silk fabric with a loosely bound paint, which I made flaky by crumpling the samples (Figure 4). I also had some non-flaky mud silk purchased in China in the 1950s, which I used to test how much the adhesives would stiffen the textile (Figure 5). I tested three different adhesives made up to different concentrations by dissolving them in water or a mixture of water and alcohol, and applied them to the samples using an airbrush. The adhesive types I tested were isinglass, made from the swim bladders of Sturgeon, a kind of fish; funori, made from Japanese red seaweed; and Aquazol 200®, a synthetic resin (Figures 6-8). I found that there were a number of factors influencing how well the adhesives consolidated the flaky paint and how much they stiffened the mud-silk. These included how thick the liquid adhesives were, how fast they dried, their concentration, and the kinds of chemical structures they were made up of. In the end, the only variations I tested that didn’t noticeably stiffen the mud-silk samples were funori in either water or a mixture of water and alcohol, at the very low concentration of 0.1%. Due to the low concentration, 13 – 15 spray applications were required to re-adhere the flakes on the painted silk samples to the textile ground, but because of the way the adhesive flowed and dried it did not change the flexibility of the mud-silk.
No treatment has been undertaken on any mud-silk garments yet; however the testing I carried out lays the groundwork for future conservation work. Often conservators don’t have the luxury of time to perform all the preliminary tests they would like to, so it is important for those of us who do testing to share our results with our colleagues. This research comprised my dissertation, in partial fulfillment of the requirements of the Degree of Master of Philosophy in Textile Conservation at the University of Glasgow, and was presented at the International Institute of Conservation’s 2014 Congress in Hong Kong.