Ink Dispersion on Qianlong Xuan Paper with Improved Ink Expression
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Journal of Materials Science & Technology 32 (2016) 182–188 Contents lists available at ScienceDirect Journal of Materials Science & Technology journal homepage: www.jmst.org Ink Dispersion on Qianlong Xuan Paper with Improved Ink Expression Shuyi Wu 1, Xinglong Wu 1,*, Paul K. Chu 2 1 Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China 2 Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China ARTICLE INFO Qianlong Xuan paper, lost two hundred years ago, was reproduced by engineers in Red-Star Xuan Paper Article history: Limited Liability Company of China. Its remarkable performance and profound historical value are highly Received 25 January 2015 regarded by artists and the paper commands very high price in the commercial market. Ink penetrates Received in revised form and spreads optimally in the paper and the words exhibit clear edges with small fluctuations because 11 July 2015 of the desirable wettability and wicking. These characteristics make it stand out from three Xuan paper Accepted 12 July 2015 samples. The good wettability, verified by contact angle measurements, is an essential prerequisite to Available online 17 December 2015 strong wicking. Attenuated total reflectance Fourier-transform infrared spectroscopy is performed to de- termine the chemical structure of Qianlong Xuan paper and the relatively large hydrogen bonding ratio Key words: contributes to the hydrophilicity. The microstructure investigated by scanning electron microscopy and Qianlong Xuan paper atomic force microscopy reveals wide fibers and a uniform fiber arrangement with good connectivity, Wettability dense network, as well as rough fiber surface. These unique properties endow Qianlong Xuan paper with Homogeneity Wicking strong wicking to improve the ink expression. & Surface roughness Copyright © 2015, The editorial office of Journal of Materials Science Technology. Published by Elsevier Limited. All rights reserved. 1. Introduction procedures and more than one hundred operations taking one to two years. Pulping is an essential process utilizing the stream in Jing Xuan paper, also called rice paper in Japan, is used widely in tra- County. Japan has used the same craft to produce Xuan paper but ditional calligraphy and painting and is a prominent type of Chinese the properties are not as good as those produced in the Jing County. handmade paper. It has been widely popular with calligraphers and It is believed that the water in the stream affects the quality of the painters since its inception in the Tang Dynasty (618–907 AD). Pro- paper. gressive calligraphers are always on the quest to show their Xuan paper underwent large development in the Qing Dynasty expression, which cannot be achieved without Xuan paper and in peaking in the period of Qianlong after its advent[2]. Emperor fact, good Xuan paper makes the arts more impressive. Qianlong, skilled in writing, was deeply in love with Xuan paper. Xuan paper manufactures are scattered all over the country. Red- The Qianlong Xuan paper that belongs to Tejingpi is the ultimate star paper mill, located in Jing County, Anhui Province, China, is one writing and painting paper. In order to attract more attention to Xuan of the best and Jing County is believed to be the home of the Xuan paper, Xing Chunrong, the chief engineer of the mill, reproduced paper, where the “traditional handicrafts of making Xuan paper” the Qianlong Xuan paper that was lost two hundred years ago by is listed as a UNESCO World Intangible Cultural Heritage[1]. collecting the related literature. The Qianlong Xuan paper, made by Xuan paper is made of pulped fibers of blue sandalwood bark the best engineer in one of the best Xuan paper companies, has and rice straws. According to different raw material ratios, Xuan paper immense historical significance, rarity and unmatched perfor- is classified into three types, Tejingpi, Jingpi, and Miaoliao, in which mance and owing to the limited supply, it commands the highest the ratios of wingceltis bark are more than 80%, no less than 60%, price. The outstanding wetting properties of Qianlong Xuan paper and about 40%, respectively. In general, the ink expression is better are determined by the chemical constituents and physical struc- for a larger ratio of the bark fibers. The production of Xuan paper ture, which are closely related to the raw materials and the uses natural materials and reagents and manual tools but the process manufacturing process and it is important to understand the sci- is complex and varies with different manufacturers. Normally, the entific reasons for the outstanding performance. production of traditional paper from raw materials requires 18 In recent years, there has been widespread investigation in ink dispersion on Xuan paper in the computer graphics community. However, ink dispersion is a complex phenomenon that involves * Corresponding author. Ph.D.; Tel.: +86 25 83686303; Fax: +86 25 83595535. the interplay between paper, water and ink constituents, thus making E-mail address: [email protected] (X. Wu). accurate physical simulation difficult. Moxi[3] simulated ink dispersion http://dx.doi.org/10.1016/j.jmst.2015.12.014 1005-0302/Copyright © 2015, The editorial office of Journal of Materials Science & Technology. Published by Elsevier Limited. All rights reserved. S. Wu et al. / Journal of Materials Science & Technology 32 (2016) 182–188 183 in absorbent paper by adopting the Lattice Boltzmann Equation (LBE) 2.2. Ink dispersion experiments method, but they neglected the effects of the paper structure on the actual process. Moreover, in many statistical physics experiments Calligraphers wrote on the three types of paper under the same on liquid transport in porous media, paper is chosen for obvious conditions, for instance, same brush, same ink density, same speed and simple practical reasons. However, scientific research in wetting and style. In order to gain further insights into the effects of ink dis- of traditionally handmade Xuan paper has been scarce, except Liu persion under the controlled conditions, the ink with the same and Hu’s report on the wetting property of Chinese ink on Xuan volume of 50 μL is dropped onto the three types of papers from the paper[4] in 1984 and Wu’s study on the relationship between the same height of 1 mm. production technique and performance of ink embellishment on Chinese Xuan paper[5]. However, both of them did not pay enough 2.3. Characterization attention to the physical mechanism. Because of the lack of good understanding and considering the lofty status of Qianlong Xuan The contact angle measurements were performed on the OCA200 paper in Chinese arts and civilization, we want to unravel why (Dataphysics, Germany), FTIR spectroscopy was conducted on a Qianlong Xuan paper is so remarkable from the scientific perspective. Nicolet Nexus 870 spectrometer, scanning electron microscopy was carried out on the Hitachi S4800 scanning electron microscopy (SEM), 2. Experimental and the roughness of the fiber surface was assessed by AFM (AFM, NanoScope IV NS4-1). 2.1. Paper samples and preparation 3. Results and Discussion Two other kinds of high-quality Xuan papers, Jingpi and Bamboo papers, are chosen for comparison. The Qianlong Xuan paper and 3.1. Ink dispersion effect Jingpi were provided by Red-star paper mill in Jing County, and Bamboo paper was purchased from a local Xuan paper agent. The In Chinese calligraphy, artists utilize flexible brushes to create paper was cut into 6 cm × 3 cm, 1.5 cm × 1.5cmand6cm× 6cm expressive strokes. Fig. 1(a–c) shows three Chinese characters, Wu pieces for contact angle measurements, scanning electron micros- Chien-Shiung, a distinguished experimental physicist as well as an copy, and attenuated total reflectance Fourier-transform infrared honorable graduate of Nanjing University (originally Central Uni- (ATR-FTIR) spectroscopy, respectively. The specimens were placed versity). No ink is added until the first two characters are completed. in an oven at 60 °C for 6 h to ensure complete water evaporation. It should be noted that the spreading of ink can be fully shown when The tested pieces weighing 0.2 g were put in 60 mL of deionized the ink in the brush is rich. The first and third characters show better water under magnetic stirring at a low speed for 8 h to separate the wetting with the characters written as soon as the ink is added on fibers while not damaging them. Afterwards, the suspension con- Qianlong Xuan paper. Moreover, the second character looks driest taining the fibers was diluted with adding 200 mL of deionized water indicating that a great deal of ink has been consumed during the and the diluted suspension was dripped onto slides and silicon chips writing of the first character, meaning that the pressure between for fiber width and atomic force microscopy (AFM) measurements the outer edge of the ink front and beneath the brush tip is larger separately. than the capillary suction pressure formed by voids between brush Fig. 1. (a, b, c) Front (left) and back (right) sides of Professor Fang’s work and (d, e, f) enlarged views of the edge of the scanned images of the ink dispersion (inset) on Qianlong, Bamboo and Jingpi Xuan paper, respectively. The scale bar is 1 mm. 184 S. Wu et al. / Journal of Materials Science & Technology 32 (2016) 182–188 Fig. 2. Photographs showing the water droplet shape on Qianlong (a), Bamboo (b) and Jingpi (c) Xuan paper, respectively. hairs. Considering the competition between the two kinds of pres- 3.3. Chemical constituents sure, it is certain that capillary effects affect the ink dispersion more significantly on Qianlong Xuan paper. The back of the artwork is also The wettability, which plays an important role in the paper, demonstrated on the right, showing that Qianlong Xuan paper has depends on both the chemical composition and geometric micro- better performance of transverse wicking, which makes the ink flow structure of the surface[7] and so the chemical composition is studied.