Fabric Composition and Wearability Analysis of Zhuanghua

As the primary material, the dyed silk thread used for Zhuanghua is mulberry silk [21]. Raw silk or degummed silk should be selected during the weaving process according to the fabric structure, function and technique. The warps require certain strength and wear resistance conditions, thus it is better to choose dyed monofilament with a higher degumming rate. The ground weft can only be seen on the back of the fabric. Therefore, during the golden age of Yun brocade, dyed plied degummed silk was chosen for the ground weft of high-grade Yun brocade garments. In contrast, dyed raw silk or silk with a low degumming rate was used for brocade produced in folk workshops or for palace decoration. The body motifs of the brocade are created with brocading weft threads, among which the most widely used is Sirong, which is a dyed degummed silk with a unique pressing process. In this way, good fluffiness can be achieved. With the development of textile materials, some synthetic fibers have also been applied to the weaving of Zhuanghua. Since around 2010, Sirong has been partly replaced by viscose rayon in the current Yun brocade market since products made of the two materials look similar.

Metal thread composed partly or entirely of gold, silver, or metallic materials is the typical yarn of Zhuanghua. According to shape, the metal thread can be divided into several types, among which the more common ones are lamella and filé, shown in Figure 3.

Fig. 3

The filé is a wrapped thread composed of a lamella wound around a dyed multifilament silk or cotton core. The lamella can be a narrow strip (0.3–0.6mm wide) made of precious or base metal or produced from metal foil to whose back side interlining made of membrane or paper is adhered, which is used for thread. The membrane interlining used for Zhuanghua is generally of animal skin or animal-gut membrane [22], such as parchment. The paper interlining made from bamboo or mulberry bark has two types: two-layer paper and seven-layer paper, created by pressing two and seven pieces of paper together, respectively. The seven-layer paper is thicker, primarily used for interlining of the filé, while the two-layer paper is soft, generally used for the interlining of the lamella. The preparation process of the two-layer paper and seven-layer paper is complicated. To simplify the production process, they have been widely replaced by a material similar to kraft paper since the early 21st century [23]. It is worth noting that there was an adhesive, Yujiao, made from colleseed oil, bone glue, etc., used to bond metal foils and interlining. Later, it was also replaced by chemical glue. However, the metal foil easily falls off in a hygroscopic state.

In terms of metal strips or foil composition, the standard metal threads for Zhuanghua are gilt and silvered membrane (paper) lamella (filé). In the Ming Dynasty (1368–1644 CE) and Qing Dynasty (1636–1912 CE), most Zhuanghua fabrics applied potion gold thread [2]. The thread is actually pure silvered lamella or filé, whose golden appearance is smoked by burning sulfur and Aucklandia lappa Decne; however, this is rare now. By the end of the Qing Dynasty (1840–1912 CE), metal threads made of alloys began to be widely used in Zhuanghua fabrics. We have collected common Zhuanghua satin woven with several typical metal threads through market research, shown in Figure 4.

Fig. 4

Figures 4a & b show gilt paper lamella and gilt paper filé, whose gold-inclusive rate of gold foil is 99%. Figure 4c displays alloyed paper lamella, and a filé composed of a lamella of polyester material is demonstrated in Figure 4d. There are significant differences between the four pieces in appearance. The gilt paper lamella is slightly narrower than the alloyed paper lamella. The filé made of polyester without an interlining is relatively finer than the gilt paper filé, hence two threads of it are used together when weaving. The colour of brocade woven with metallic lamella or filé is light yellow, which cannot achieve the golden and gorgeous appearance of brocade woven with the gilt variety.

Peacock feather thread (Figure 5a) is the most distinctive yarn of Zhuanghua. Its raw material is selected from freshly fallen peacock tail feathers. A manual twisting method is employed to spiral fine down feathers onto silk thread. Usually, the feathers are in ideal shapes and similar sizes. The twisted peacock feather thread must also be steamed and shaped at a high temperature to smoothly unwind during weaving. Meanwhile, it helps to achieve sterilisation and mothproofing.

Fig. 5

An enlarged image of peacock feather thread is shown in Figure 5b. It illustrates that there are regular horizontal stripes distributed on the surface of a single fiber of the fine down feather. Thus, the colour of peacock feather thread is not decided by pigments but by the interaction between natural light and wavelength-similar structures [24]. The surface of the down feather is shiny like metal, with dark and bright sides. When the light shines on it directly, its unique photonic crystal structure will change its colour. Consequently, when observing the peacock feather thread from different angles, we can see various colours, such as brown, purple, blue, green, and black [25]. The fine down feathers of the thread are irregularly tortile in shape due to the manual twisting, making the yarn curly and fluffy. Meanwhile, Zhuanghua woven with peacock feather thread has a noticeable relief effect (Figure 5c).

Yun brocade was generally woven on a drawloom (Hualou), which is a handloom equipped with a figure harness composed of leashes that control all warp ends to form the pattern. There are two types of drawlooms: small and large. They are installed and built according to the type of Yun brocade and are different in selecting and pulling cords, the weaving technique, and other aspects. The mechanism of the small drawloom is relatively simple, and it is suitable for brocade with simple motifs, such as Kuduan. In the weaving process, completing a piece of brocade requires the tacit cooperation of the drawboy and the weaver [27], as shown in Figure 7a.

Fig. 7

The drawboy pulls the lashes on the drawloom to control the warp ends that must be raised. The weaver needs to raise or lower shafts by treading the foot pedal of the loom to produce sheds for the passage of the weft, which enables shuttles to be thrown in the required place. Figure 7b shows a large drawloom with more than 1,000 components [28]. It is a particular loom for weaving Zhuanghua with a body length of 560 cm, height of 400 cm, and width of 140 cm. It is a significant invention in brocade weaving and even in the silk weaving industry, showing the wisdom of ancient Chinese craftsmen [29].

There are dozens of traditional Zhuanghua weaving processes, which require joint effort and meticulous workmanship from design to production. The processes [2] include pattern and motif design, pattern grid drawing, the cross-stitch plain-knit procedure, yarn preparation, loom loading, final weaving, etc. Among them, the following three techniques are essential: The first is drawing the pattern grid, which is to draw the required patterns on squared paper. Each vertical grid represents a group of warp yarns, while the horizontal one represents a brocading weft (one colour represents one specification of the brocading weft). The second is the cross-stitch plain-knit procedure [30], a bridge for the pattern from the sketch to the fabric. It uses the old way of knotting notes to store colour and pattern information according to the pattern grid. Then a “program,” just like a computer program, is obtained and then placed on the drawloom to guide the operation of the drawboy. The last is the Zhuangzhi weaving process, which is the core weaving technique of Yun brocade. With the Zhuangzhi technique, the patterns and motifs are created by the small brocading shuttles wrapped with brocading weft threads, and the number of brocading wefts can reach nearly 30 in the same weft direction. In addition, brocading weft threads of different colours can be flexibly changed in any position of the required pattern. This technique is also known as warp-through and weft-back. Unlike the warp-through and weft-broken of Chinese Kesi, the weft-back of Zhuanghua is connected at the other end, and its patterns and motifs are produced by weft-back brocading wefts [31].

Compared with plain satin, the fabric composition of the Zhuanghua satin was more complicated. It consisted of warp, ground weft, and brocading weft (including Sirong and gilt paper filé). The warp thread was monofilament silk after degumming, while the ground weft thread, made from cooked silk with little twists, was plied yarn. There were a dozen colours of Sirong made from degummed multifilament silk without a twist. The specific yarn parameters are shown in Table 1.

As shown in Figure 8a, the plain satin was 7/4 warp-faced satin, and the ground weave of the Zhuanghua satin was consistent with it, while the flower weave of the Zhuanghua satin was 7/2 satin. It can be seen from Figure 8(b) that the floats of the Sirong and gilt paper filé were controlled by fourteen heddles interfilar points. And the proportion of the brocading weft to the ground weft was 1:2.

Fig. 8

Table 2 gives detailed parameters of the yarns in the selected samples. The density of the brocading wefts (Sirong) of A1–A3 (149/10 cm) and B1–B3(155/10 cm) measured was found to be different from the ideal data (140/10 cm and 160/10 cm, respectively). This is likely to be an error caused by hand weaving, which explained why the ratio of the ground weft density to the brocading weft density of the Zhuanghua satin was close to 2:1 rather than 1:1.

Detailed parameters of the 12 samples are shown in Table 3. Since the Zhuanghua satin was decorated with supplementary brocading wefts on the plain satin base, the grammage of the Zhuanghua satin was heavier than the matching sample.

Combined with the fabric weave characteristics of the Zhuanghua satin (Figure 8b), we found that the thickness of the Zhuanghua satin was uneven, and it was thicker than plain satin overall. This is because the brocading weft floats of varying lengths were stacked on the back of the Zhuanghua satin when applying the Zhuangzhi technique. The more brocading weft floats stacked, the heavier the fabric would be.

The fabric’s air permeability was tested by an FX3300 textile air permeability tester (Wenzhou, China) according to the standard GB/T 5453-1997 [32]. The evaluation index was the mean air permeability (mm/s), and the pressure difference was 10Pa. Each fabric was tested ten times, and the average was taken as the final result.

The fabric’s moisture permeability was tested by a YG(B)216 textile moisture permeability tester (Wenzhou, China) according to the standard GB/T 12704.1-2009 [33]. Three samples with a diameter of 70 mm were selected for each fabric. The measurement was performed with an oven (heating temperature of 160°C, humidifying temperature of 38±2°C, and relative humidity of 90±2%. The evaluation index was the water-vapour transmission rate [g/(m²·d)]. Each fabric was tested three times, and the average was taken as the final result (accurate to 0.001 g).

The fabric’s stretch resilience was tested by a YG026PC-250 textile electronic tensile strength tester (Wenzhou, China) according to the standard GB/T 3923.1-2013 [34]. Five rectangular samples with a size of 50×320 mm were selected for each fabric in the warp and weft directions. The interval length of the fabric test was set to 200 mm, and the stretching speed was 20 mm/min. The evaluation indexes were the breaking force (N) and elongation at break (%). Each fabric was tested five times, and the average was taken as the final result.

The fabric’s crease recovery property was tested by a YG541E automatic textile wrinkle elasticity tester (Wenzhou, China) according to the standard GB/T 3819-1997 [35]. Five “T”-shaped samples were selected for each fabric in the warp and weft directions. The evaluation index was the crease recovery angle (°). Each fabric was tested five times in the warp and weft directions, and the average was taken as the final result.

The fabric’s stiffness was tested by a YG(B)022D automatic textile stiffness tester (Wenzhou, China) according to the standard GB/T 18318-2001 [36]. Six rectangular samples with a size of 25×250 mm were selected for each fabric in the warp and weft directions. The evaluation index was flexural rigidity. Each fabric was tested six times in the warp and weft directions, and the average was taken as the final result.

The fabric’s propensity to surface fuzzing and pilling was tested by a YG502 textile fuzzing and pilling tester (Wenzhou, China) according to the standard GB/T 4802.1-2008 [37]. Five samples with a 113±0.5 mm diameter were selected for each fabric. The test pressure was 590 cN, and the number of fuzzing and pilling was 50. The evaluation index was the grade of anti-fuzzing and anti-pilling, which was evaluated by comparing the woven fabric fuzzing and pilling grade sample card (Suzhou Silk Research Institute) of woven fabrics. Each fabric was tested five times, and the average was taken as the final result.