Liu et al. Herit Sci (2021) 9:13 https://doi.org/10.1186/s40494-021-00486-4 RESEARCH ARTICLE Open Access A new method for the conservation of ancient colored paintings on ramie textiles Jiaojiao Liu*, Yuhu Li*, Daodao Hu, Huiping Xing, Xiaolian Chao, Jing Cao and Zhihui Jia Abstract Textiles are valuable cultural heritage items that are susceptible to several degradation processes due to their sensi- tive nature, such as the case of ancient ma colored-paintings. Therefore, it is important to take measures to protect the precious ma artifacts. Generally, ″ma″ includes ramie, hemp, fax, oil fax, kenaf, jute, and so on. In this paper, an examination and analysis of a painted ma textile were the frst step in proposing an appropriate conservation treat- ment. Standard fber and light microscopy were used to identify the fber type of the painted ma textile. Moreover, custom-made reinforcement materials and technology were introduced with the principles of compatibility, durabil- ity and reversibility. The properties of tensile strength, aging resistance and color alteration of the new material to be added were studied before and after dry heat aging, wet heat aging and UV light aging. After systematic examina- tion and evaluation of the painted ma textile and reinforcement materials, the optimal conservation treatment was established, and exhibition method was established. Our work presents a new method for the conservation of ancient Chinese painted ramie textiles that would promote the protection of these valuable artifacts. Keywords: Painted textiles, Ramie fber, Conservation methods, Reinforcement, Cultural relic Introduction Among them, painted ma textiles are characterized by Textiles in all forms are an essential part of human civi- the fexibility, draping quality, heterogeneity, and mul- lization [1]. Te raw materials that have been used for tiple layers, making them complex objects to conserve. textiles include cotton, ma, silk, wool, goat hair, and so Ma textiles are made of ma including ramie, hemp, fax, on. Previous reports mainly focus on the degradation and oil fax, kenaf, jute, and so on [21]. China has a history ageing of linen, wool and silk textiles [2–5], the preser- of more than fve thousand years and since the Liao and vation environment of archaeological textiles [6, 7], the Jin era are signifcant periods in ancient China, many ma- analysis and identifcation of textile components [8–13], colored paintings from Buddhist culture and history have the fungal contamination and splicing technology of tex- been preserved (Fig. 1). Tese works provide an impor- tile objects [14, 15]. After the frst conference on textile tant reference to understand the historical prosperity, conservation held by IIC in Te Netherlands in 1964 [16], decline and nature of Buddhist culture in the Chinese certain textile conservation methods have been devel- Liao and Jin era. Unfortunately, all textiles, including ma oped, including disinfecting of textile objects [17], clean- textiles in museums are exposed to many risks such as ing [18], mounting [19], and stitching techniques [20]. uncontrolled relative humidity (RH) and temperature, It is well known that ma textiles have been used for light and air pollution, and non-standard storage and making uniforms, ropes, paintings, and scriptures. display methods [22, 23]. Te ma fbers are hygroscopic, thus they could react with water, carbon dioxide, and also *Correspondence: [email protected]; [email protected] sulfur dioxide in the air leading to deterioration of the Engineering Research Center of Historical Cultural Heritage Conservation, fbers [24]. In addition, the deposition of dust and micro- Ministry of Education, School of Materials Science and Engineering, organisms on the surface accelerates chemical reactions Shaanxi Normal University, Xi’an 710119, China that lead to loss of tensile strength and pliability [25]. As © The Author(s) 2021, corrected publication 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. 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Herit Sci (2021) 9:13 Page 2 of 10 Fig. 1 The painted ma textile object dates to Chinese Liao and Jin era (160 30 cm) × a result, the ornamental value of ma fabric is afected. below have been lost, and both have height of 160 cm and As far as we know, there are few studies on conservation width of 30 cm. Te body of this pair of banner-hanging methods of painted ma textiles. Previously, research- Bodhisattvas showed the image of Bodhisattvas in Early ers [26, 27] reported some analytical techniques for the Indian Buddhism, and it is a rare Buddha painting made identifcation and characterization of textile materials, on ramie fber. Te painting shows light and dark expres- the categorization of painted textile, and a collaborative sive methods, and the painting style has characteristics approach between textile and paintings conservators on that integrate many artistic features of India, Greece and lining and mounting painted textiles. the Western Regions of China. Tis pair of the colored Good conservation policy for painted ma textiles ramie drawing Bodhisattva banner-hangings originates should not be only about protection against the risks from the Western Regions of China during the North- caused by environmental factors, but also about the use ern and Southern Dynasties [30]. As shown in Fig. 2, of appropriate conservation methods, required by scien- there were many signs of damage on the object, such tifc research. In this article, the selection of reinforce- as many missing areas and weft yarn. ment materials was the frst step for these conservation methods. Reinforcement materials should possess an Characterization of ma fber in the painted textile appropriate structure, weight, and fber to provide ade- Based on the compatibility principle of reinforcement quate support to the ma textiles [28]. Tereby, the type of materials, this experiment applied one analysis method fbers and extent of damage were studied through difer- to identify the fber type of colored painting of ma textile. ent ways of investigation. Before the identifcation on the Preparation of Herzberg coloring agent and samples has fber type of the original object, painted ma textile was been reported [31, 32]. Light microscopy (LM) was used used. After it is completed, painted ramie textile, ramie to observe and compare the fber morphology of ma fber fber or ramie net was used. Ten, based on the princi- from painted textile and standard fber. ples of compatibility, durability and reversibility, the new reinforcement materials and techniques were decided. Evaluation of reinforcement material Finally, the conservation methods of the Chinese painted Te Xi’an Yuanhaohuazang Museum has collected ramie textiles were developed, including realignment of the colored ramie paintings of the Chinese Liao and the distorted weave, consolidation of the painting layer, Jin era, and samples were taken from the fragments of wet cleaning and stain removal, fne realignment of the the degraded colored ramie paintings. Te reinforce- fbers, reinforcement of the ramie net and in-fll of areas ment material was prepared with the ramie net. Polyvi- of loss. Tis work aimed to propose conservation meth- nyl alcohol 217 (PVA-217), ramie fber and water-based ods for Chinese painted ramie textiles, which would fuororesin were purchased from a commercial company enrich conservation scientist’s information about the and used as received. conditions of conservation and physical chemical proper- ties of reinforcement materials [29]. Accelerated aging of reinforcement material Tree general aging methods were employed for the Experimental accelerated aging of the reinforcement material, and Historical context three parallel experiments were carried out for each As shown in Fig. 1, there is a colored ma drawing: a pair group of aging methods. Each sample was aged for 3, 5, of Bodhisattva banner-hangings. Te banner hand on and 7 days. Heating textiles or paper for 72 h (3 days) at the left and right of the banner body and the banner foot 100 °C is equivalent of approximately 25 years of natural Liu et al. Herit Sci (2021) 9:13 Page 3 of 10 Fig. 2 The types of damage of the ma textile colored painting (a): There are mainly two signs of damage on this object: missing areas (b); missing weft yarn (c) aging under normal condition [16]. One aging method 7 days, and each sample was measured 5 times to get the was dry heat aging, the prepared ramie net and PVA flm average value. Four layers of ramie net were superim- were put in a blast drying aging box at 105 °C. Te second posed to perform the test. Te larger the value of ∆E*, the method was wet heat aging, the prepared ramie net and greater the color change of the sample. PVA flm were put in a constant damp heat aging test box at a temperature of 80 °C and a relative humidity of 65%.