Experimental Exploration of Restoring the Broken Strip Disease of Collections of Calligraphy and Painting Based on Hydroxypropyl Methyl Cellulose

Abstract: "Broken strip disease" is the most common disease of calligraphy and painting in the collection, which is related to the previous preservation environment and its own complicated transmission experience. The traditional method of repairing the "folding strip disease" is usually adopted - pasting the folded strips, but this method treats the symptoms but not the root cause. "Broken strip disease" is fundamentally due to repeated effects of paper aging and external force. Before pasting the folded strip, it is reinforced with hydroxypropyl methylcellulose (HPMC). , folding tester to measure the effect of this repair method, the results show that the gap at the folded strip of the "broken strip disease" sample treated with hydroxypropyl methylcellulose has been well filled, and the color difference is within 1.56. The gloss is almost unchanged, there is no glare effect, and the folding endurance is increased by more than 8 times. Reinforcing with hydroxypropyl methylcellulose and pasting folded strips is a simple and effective way to treat the "folded strip disease" of calligraphy and painting.

Key words:calligraphy and painting in the collection; "broken strip disease"; hydroxypropyl methylcellulose (HPMC); folded strips; reinforcement

Collections of calligraphy and painting are generally attacked by "folding disease", which is manifested as several creases on the surface of the painting center, and such creases can basically be seen under copying tables and metering lights. "Folded strip disease" is divided into open folded strips and hidden folded strips. The creases that have been broken or seem to be broken are called open folded strips; Hidden, making it invisible to the naked eye, and easily overlooked during restoration. The essence of "folding strip disease" is the aging of paper, which is the local highlight of paper aging, or the local cellulose breakage caused by external force factors, such as repeated opening and rolling, and the influence of storage environment, such as high temperature and humidity , Acidification and other conditions, the stress is formed between the painting center, the supporting paper, and the backing paper, resulting in the "broken strip disease". The "folding strip disease" shows a series of creases on the outside, but in fact, the heart of the painting has been broken. Because the descendants have remounted it many times, the backing paper and the backing paper are intact, so the appearance of the creases appears on the outside. At present, the traditional method of sticking folded strips is mainly used in the treatment of "folded strip disease". Zhou Haikuan uses the traditional way of sticking folded strips in actual repair work. The specific method is to cut the rice paper into strips of 3-5mm, and paste them on the folded strips according to the trend of the folded strips. There are two situations: one is to cut the rice paper strips directly with a single layer of rice paper, which is suitable for re-mounting. On the painting and calligraphy, paste it on the back of the painting heart that has been supported by Xiaotuo; the other is to use rice paper (two layers) that has been carried by Xiaotuo to cut rice paper strips, which are thicker and harder, and are suitable for paintings and calligraphy with slight "folding strip disease". , not demounted, directly pasted behind the backing paper.

There are few people who study the repair of "broken strip disease", and they mainly focus on the improvement of traditional technology and technology, and have not combined with modern repair materials. The patent developed by the Shang Xiaolin team of Shaanxi Normal University to repair the "broken strip disease" is based on the traditional broken strip repair method. Different repair methods are adopted according to the degree of the "broken strip disease" and the details are improved. Jia Xiaoyan, Li Jing This method has also been applied in the actual repair work, and achieved good results. Although repeated heating can make all the hidden folds appear in the mid-term "folded strip disease", the author believes that repeated heating is not conducive to the preservation of calligraphy and painting. One of the principles of cultural relics protection is minimal intervention, that is, the preservation status is stable so that it will not continue to deteriorate. In the late period of "folding strip disease", white silk was used to reinforce it, which may increase the thickness of calligraphy and painting and affect the mounting effect. Moreover, the technical requirements of restorers are very high, and it is difficult to practice without hard work. Painting and calligraphy mounting restoration is a long-standing traditional craft in our country. It has been taught by teachers for a long time. However, many mounting masters have traditional ideas and form a barrier between technology and science. It is necessary to break this barrier.

There are many studies on hydroxypropyl methylcellulose (HPMC), which are concentrated in various fields: industry, medicine, food and other fields, indicating that this material has excellent performance and wide compatibility. However, it is rarely used for paper restoration. Zhang Xiaomei and Su Jing from the School of Archeology and Museology of Peking University have studied the excellent performance of hydroxypropyl methylcellulose in strengthening fragile paper.

Liang; Fan Xiaoyu and Hu Daodao from the Engineering Research Center of the Ministry of Education for the Protection of Historical and Cultural Heritage of Shaanxi Normal University, etc. obvious. However, this method is only used for the reinforcement of aging paper, and has not been applied to the restoration of calligraphy and painting mounting, nor has it been applied to the restoration of the "folded strip disease" of calligraphy and painting.

The traditional "broken strip disease" repair method is local reinforcement, which has limitations, and hydroxypropyl methylcellulose has not been directly used for the repair of "broken strip disease" in calligraphy and painting. Based on the traditional repair method of "broken strip disease" - sticking the folded strip method, at the same time using the reinforcement effect of hydroxypropyl methylcellulose on the paper, combining the two, when repairing the "broken strip disease", first use hydroxypropyl methylcellulose It is a simple and effective method to paste the folding strips after treating the base methyl cellulose. Therefore, this paper compared the differences in microscopic morphology, color difference, gloss, and folding resistance between hydroxypropyl methylcellulose-treated and untreated "broken strip disease" samples.

1. Experimental part

1.1 Reagents and instruments

Reagents: hydroxypropyl methylcellulose (produced by KIMA CHEMICAL CO., LTD), alum (AR) (produced by Tianjin Shengao Chemical Reagent Co., Ltd.).

Instruments: Electrothermal constant temperature blast drying oven (DHG-9070A, produced by Shanghai Qixin Scientific Instrument Co., Ltd.); super depth-of-field microscope (KH7700, Hiroshi, Japan); spectrophotometer (CM700D, Japan); gloss meter (DTG60M, Changzhou Dedu Precision Instrument Co., Ltd.); folding tester (MIT, the brand is Tianshi Olsen).

Experimental preparations: flour (the brand is Xiangmanyuan), Shengxuan (produced by Wuxing Xuan Paper Factory in Jingxian County, Anhui Province), and a small watering can.

1.2 Sample preparation

Simulated creases: Since the naturally formed creases cannot be quantified, artificial creases are artificially made and the paper is properly aged to simulate the "crease disease". Prepare two sheets of 30cm×30cm rice paper, overlap the two sheets of rice paper, and cut 6 slits with a paper cutter. The direction of the slits is consistent with the direction of the paper curtain grain, and the length is 15cm. Artificially create broken marks to simulate the shape of folded strips. Because the "broken strip disease" is actually the fracture of the center of the painting caused by the aging of the paper and the external force, in order to facilitate the detection with the folding tester, the "broken strip disease" is quantified, and the cut is the manifestation of the "broken strip disease". strengthening of the form. After the paper is lifted, the whole paper is aged, and the formation method of "folded strip disease" is simulated.

Prepare the paste: use the brewing method, take 250g of flour, add an appropriate amount of warm water and stir it evenly with a wooden stick, add a small amount of hot water and stir vigorously to make the batter slightly thinner, and finally wash it with boiling water, and stir it with a wooden stick until the batter is Thin and thicken, light yellow in color, and brushed when provoked. Boil the water to submerge the paste. After cooling, add cold water to submerge the paste. The paste is completed. To make slurry, use a bamboo screwdriver to cut the paste into small pieces, dip your hands in cold water to take out a small piece, first add a small amount of water, stir with a wooden stick until there are no particles, then add water in batches, and stir while adding water until it becomes a pan. Rice water color, stir evenly with a paddle.

Supporting the heart of the painting: Hold the prepared 30cm×30cm rice paper separately, with the back of the rice paper facing up, brush the pen dipped in starch water on it, and move the brush in a rice-shaped shape, so that the rice paper is evenly covered with starch water, and take a piece slightly larger than For the heart-painting rice paper, put the backside up on the heart painting, brush it flat with a brown brush, and let it dry, with the supporting paper in the same direction as the curtain pattern of the heart painting. Because the traditional folding method is to paste the folding strip on the back of the painting center behind the small support, and make samples according to the same requirements. In order to ensure the accuracy of the experimental results, the direction of the curtain lines of the two samples is the same, which is mainly considered for the measurement of the folding endurance.

1.3 Proper aging of samples

Spray the alum solution evenly on two 30cm×30cm rice papers supported by the support, the concentration is 10mol/L, and the amount of each spray is 20ml, so that the paper is acidic. Refer to GB/T464 2008, place the sample in an oven at 105°C for 72 hours, take it out, wet it with a watering can and roll it up, then place it in the oven after drying, repeat three times, so that the paper repeatedly experiences high temperature and humidity in a short period of time environment, and repeated folding and opening, so that the sample is properly aged.

1.4 Preparation of hydroxypropyl methylcellulose solution

Heat water and stir quickly during preparation to prevent agglomeration. The preparation concentration is 20mol/L, and it is set aside after cooling. Spray with a watering can to make the hydroxypropyl methylcellulose solution cover more evenly. If the method of soaking is adopted, the painting heart is easy to rot after being picked up. Sample 1 sprayed the hydroxypropyl methylcellulose solution evenly, sample 0 took no action. In order to reduce the variable factors in the experiment and unify the test conditions, the folded strips were not actually attached, and only the difference between the "broken strip disease" samples treated with and untreated by hydroxypropyl methylcellulose was compared.

2. Analysis and detection

2.1 Micro analysis

Use a super depth-of-field microscope to observe the microscopic morphology of the hydroxypropyl methylcellulose-treated and untreated folded strips, take the same position, observe the difference between the folded strips and the nearby positions, and observe at a magnification of 200 times, using a lens of MX (G )-5040Z. Because the paper is thin and light, heavy objects can be used to press the surrounding area when it is fixed on the observation platform.

2.2 Chromatic difference analysis

Chromaticity changes can reflect the influence of hydroxypropyl methylcellulose on the color of the paper body. The larger the color difference value, the greater the material’s color change to the paper. The change in paper color was minimal, demonstrating the usability of the material. Use a spectrophotometer to test the brightness L, red-green contrast a, and yellow-blue contrast b of hydroxypropyl methylcellulose-treated and untreated "broken stripe" samples, and use the formula to calculate the color difference △E. The test method is to test the spectrometer on the surface of the sample after black and white plate calibration, and take the midpoint of the folded strip of the sample, and take six points for each sample to calculate the color difference value.

2.3 Gloss measurement

Gloss can reflect the ability of the surface of the material to reflect light, and hydroxypropyl methylcellulose will be gelatinous at high concentrations, so it is necessary to test the gloss of hydroxypropyl methylcellulose covering paper at low concentrations to judge whether it is There will be a glare effect. A gloss meter was used to test the glossiness of the hydroxypropyl methylcellulose-treated and untreated "broken stripe" samples, and the observation angle was 60°. Test method: first calibrate the gloss meter, take the midpoint of the folding strip, measure six data for each sample, and take the average value.

2.4 Folding Endurance Test

Folding resistance refers to the ability to withstand 135° reciprocating folding under a certain force, and the folding resistance can be a good measure of the effect of the repair of "broken strip disease". Use the folding endurance tester to measure the folding endurance times of hydroxypropyl methylcellulose-treated and untreated "broken strip disease" samples. Because the rice paper is thin and soft, the test conditions are 0.5kg applied force and 175 folding times per minute. . The test method is to cut the "broken strip disease" sample into a strip with a length of 14cm and a width of 1.5cm according to the national standard GB/T2679.5-1995, and place it between the upper chuck and the lower chuck to measure the effective distance 7cm, ensure that the upper and lower chucks clamp the folded strip, keep the paper strip vertical and taut, measure the number of folding endurance respectively, and take the average value.

3. Results and Discussion

3.1 Filling effect

Hydroxypropyl methylcellulose has a very good filling effect between the fiber gaps. The form of "broken strip disease" is fiber fracture, which is like a ravine in the microscopic state. The crevice ravine pulls the fibers on both sides, so it needs A bridge is used to connect the fibers on both sides, and hydroxypropyl methylcellulose plays this role well.

After treatment with hydroxypropyl methylcellulose, there are a lot of white particles in the cracks and surrounding fibers of the folded strips, and the folded strips are well filled. Hydroxypropyl methylcellulose is a kind of cellulose ether, a kind of derivative of cellulose, which is a product in which the hydrogen atoms of the hydroxyl groups in the cellulose molecule are replaced by alkyl or aromatic hydrocarbon groups. Hydroxypropyl methyl cellulose is amphiphilic, and there are both hydrophilic groups and hydrophobic groups, which can more comprehensively and perfectly integrate the excellent properties of cellulose ethers, and have better stability than other cellulose ethers . The structure of hydroxypropyl methylcellulose is similar to that of paper, both of which are cellulose components, which can form bridges and fill between broken paper fibers.

3.2 Colorless and transparent properties

After treatment with hydroxypropyl methylcellulose, the L value of the "broken strip disease" sample dropped a little bit, and the range of △L was between (-1.51) and (-0.46), indicating that after treatment, the brightness of the paper was slightly reduced ; △a ranges from -0.1 to 0.06, △b ranges from 0.22 to 0.4, and the values of a and b hardly change; The change that cannot be detected by the naked eye shows that the color difference caused by the "broken stripe disease" treated by hydroxypropyl methylcellulose is negligible. Due to the appreciation and value of calligraphy and painting, the requirements for brightness and chroma are relatively high. The difference in gloss between hydroxypropyl methylcellulose-treated and untreated samples of "broken bar disease" is only 0.3, and the gloss has hardly changed. Although Hydroxypropyl methylcellulose has the effect of strengthening the paper, but it is not a glue, and it is diluted to a certain extent, so it will not have a strong reflective effect. Hydroxypropyl methylcellulose is colorless and odorless when dissolved in water, and it is not sticky at low concentrations, so it hardly affects the color and gloss of paper.

3.3 Improve the folding strength

The folding resistance of the "broken strip disease" sample treated with hydroxypropyl methylcellulose was greatly increased, and the folding resistance was more than 8 times that of the untreated one. "Folded strip disease" shows a series of creases on the surface, but in fact, the center of the painting has been broken, the strength of the paper is reduced, and the folding resistance is reduced. The structure of hydroxypropyl methylcellulose is similar to that of paper, which can effectively fill the fiber gaps and surrounding fibers at the breakage of the folded strips, form a bridging effect between the fibers through hydrogen bonds, improve the strength of the center, and then paste on the back The folding strips greatly enhance the folding endurance of the paper.

4.Conclusion

By simulating the "broken strip disease" sample, compare the microscopic morphology of the hydroxypropyl methylcellulose treated and untreated samples under the ultra-depth microscope, measure the color difference value with a spectrophotometer, measure the glossiness with a gloss meter, and fold resistance The tester measured the number of times of folding endurance, and the results showed that the "broken strip disease" sample treated with hydroxypropyl methylcellulose, the gaps and fractures of the folded strip and the nearby fibrous tissue were well filled, which played a role in reinforcement. Function, the color difference value within 1.56 is a slight change, the glossiness is almost unchanged, and the folding resistance has increased by more than 8 times. It is concluded that treating "broken strip disease" with hydroxypropyl methylcellulose treatment and then sticking strips is a simple, convenient and effective method, which can realize the combination of traditional restoration technology and modern restoration materials.

The results of this research in the laboratory are relatively satisfactory. On the basis of full evaluation and demonstration, we will try to apply it to calligraphy and painting with "broken strip disease". Reinforcement technology, restoration process, in order to obtain good results of calligraphy and painting restoration.