Emperor Taizong wrote letters on hemp paper and yellow paper; Emperor Gaozong ate it with white paper and issued "imperial edict and jute paper". Later, due to the serious damage to books, artists and painters from all over the world were called to Beijing to repair the books in the imperial palace. During the reign of Xiaozong in the Southern Song Dynasty, many books such as Zuo Zhuan and Guoyu were eaten by insects. Ten books were made of dates and pepper paper, and none of them had been eaten by insects until about 600 years in the Qing Dynasty. It can be seen that all previous dynasties attached great importance to the preservation and maintenance of paper cultural relics.
The evolution of paper cultural relics is directly related to the invention of the main constituent material paper and the improvement of papermaking. Describe it as simply as possible.
The invention of the first 1 PaperSmart
When was paper invented? Who invented it? Academic circles have been arguing about this for a long time. It is generally believed that paper was invented by Cai Lun, the eunuch of the Eastern Han Dynasty. With the in-depth development of archaeological work, the unearthed paper cultural relics provide us with valuable physical specimens to answer the question of the origin of paper. 1933, an archaeologist, Mr. Huang Wenbi, discovered hemp paper at the beacon tower site of Han Dynasty in Luobuzhuoer, Xinjiang. 1957 On May 8th, the hemp paper of the Western Han Dynasty was unearthed near Anba Bridge in Xi 'an, Shaanxi Province (some papermakers and academics thought it was hemp instead of paper), and the hemp paper of Emperor Xuan Di was found in Fufeng, Shaanxi Province 1978. And ancient scraps of paper unearthed in Wuwei, Gansu and Inner Mongolia. The discovery of these objects proves that our people have invented papermaking with plant fibers long before Cai Lun.
During the Eastern Han Dynasty (A.D. 105), Cai Lun summarized the experience of folk papermaking on the basis of predecessors' practice, and improved, perfected and popularized it with the help of the equipment provided by the government, which made an unprecedented breakthrough in papermaking. Since then, China's paper industry has been further developed.
In the second quarter, the process of papermaking in China.
First, the beginning and development stage of papermaking in China.
After Cai Lun, on the basis of summarizing the papermaking technology in Cai Lun, Zuo Bo further revised the papermaking raw materials and technology. If the Western Han Dynasty was the initial stage of China's papermaking, then the Wei, Jin, Southern and Northern Dynasties entered the development stage. Compared with the Han Dynasty, papermaking in this period not only improved the output and quality, but also expanded the raw materials for papermaking, updated the equipment and appeared new technologies. In addition, measures such as soaking paper with Huangnie juice to prevent moth-eaten are the first of our people's yellow dyeing technology.
Second, the prosperous period of papermaking in China
The Sui, Tang and Five Dynasties were the heyday of papermaking in China. Compared with Wei, Jin, Southern and Northern Dynasties, the raw materials for papermaking were further expanded and the cost was reduced, so paper products were widely used in daily life. At the same time, some progress has been made in improving the properties of pulp and transforming papermaking equipment. With the cultural exchange with foreign countries, papermaking spread from east, west and south to Japan, Arabia, India, Nepal and other countries in Southeast Asia, East Asia and West Asia.
Third, the mature stage of papermaking in China
The Song and Yuan Dynasties were called the mature stage of ancient papermaking in China. The raw materials for papermaking have changed from bark, hemp, rags and old fishing nets to bamboo, straw and straw. Due to the expansion of papermaking raw materials, the innovation of papermaking technology and the improvement of papermaking equipment, more and higher papers were produced in this period than the previous generation, such as bamboo paper and wheat straw paper, marking a new era in papermaking history. Paper is widely used in painting, printing, currency and so on. At the same time, paper products have also been used to make clothes, curtains, quilts and pillows, becoming a partial substitute for silk and textiles.
Fourthly, the comprehensive period of papermaking in China.
Paper-making in Ming and Qing Dynasties can be said to be a comprehensive stage, not only the raw materials, technology, equipment and processing of paper have been greatly improved, but also the output, quality, use and origin of paper have increased compared with the previous generation. There are even books devoted to papermaking and processing technology, which were rare in the previous generation.
Five, the beginning of modern industrial papermaking in China.
With the increasing demand for paper, traditional hand-made paper can no longer meet the requirements of social development and daily life. Under the influence of the wave of industrial revolution, Dacheng Paper Mill was set up in Hong Kong in the 13th year of Guangxu reign (1887), and Li Hongzhang introduced western European paper machinery and technology in189/kloc-0, and set up a machine-made paper mill-Zhang Lun Paper Mill in Shanghai. Since then, China's paper industry has entered the stage of machine manufacturing, and then "Zhang Lun Paper Mill" was established in Pudong. By 1978, there are more than 70 paper mills in Taiwan Province province, and the output of paper and paperboard ranks 22nd in the world.
Before paper was invented or widely used, characters were engraved on tortoise shells, animal bones, jade articles and metals, and some were written on bamboo slips, wooden slips and silk books. Because of their huge size, these carriers are extremely inconvenient to store, read and carry, and it is difficult to popularize and popularize, which hinders the spread and exchange of culture. With the invention, production and use of paper, paper has become the carrier of writing, painting and printing and an indispensable material in daily life. It has played a great role in the widespread dissemination of ideas and academics, and is of epoch-making significance in promoting the progress of human society.
Manuscripts, books, paintings, classics, newspapers, and documents left over from past dynasties are all historical records, and are the original materials for studying history, political metallurgy, science and technology, culture and art, which are not only abundant in quantity, but also rich in content. They are the precious cultural wealth of the Chinese nation and are of great value to the study of human social progress and scientific and technological development.
With the passage of time, due to internal factors (acidification and material changes) and external factors: drastic changes in temperature and humidity, light, erosion of harmful gases, insect decay, microbial growth, mechanical wear, rat bites, fires, floods, etc. Paper will deteriorate and be damaged, and even cause irreparable losses. Therefore, it is an urgent task to study the causes of paper damage and its maintenance methods to prolong its service life.
Chapter II Composition Materials of Paper Cultural Relics
Paper cultural relics are composed of paper, writing ink, printing ink, painting pigment and adhesive. The quality of these materials is directly related to the internal factors of whether paper cultural relics can be preserved for a long time.
Section 1 Main raw materials for papermaking
Paper is the main material of paper cultural relics, and the types of paper can be divided into manual paper and mechanical paper. Handmade paper includes hemp paper, leather paper, rattan paper, bamboo paper, cotton paper, rice paper, wool paper, historical paper and so on. At the end of 19, handmade paper was gradually replaced by machine-made paper. Newsprint, printing paper, typing paper, glossy paper, picture paper and kraft paper are commonly used.
The main raw material of papermaking is plant fiber, and there are many kinds of plant fiber, which can be basically divided into bast fiber, stem fiber and seed hair fiber.
Table 1 Types of Paper Plant Fibers
woody plant
Mulberry, bamboo and rattan
Stem fiber
annual
Straw, straw, reed
perennial plant
bamboo
Seed wool fiber
cotton
First, bast fiber:
It is the main raw material of ancient papermaking. Because it contains a lot of cellulose, it is generally between 60% and 83%. In addition, the fiber length is 120 ~ 180mm, and the fiber length-width ratio is about 950 ~ 1230 times. Because bast fibers are long, paper is tough.
Second, the stem fiber:
Such as bamboo and straw. Its cellulose content is between 24% and 60%, and its length-width ratio is about 100 ~ 200 times. In different periods, the composition and properties of paper are different, and what materials and processes are used to make it.
Third, the hair fiber:
For example, cotton has the purest and most cellulose content, which can generally reach more than 90%. The length of the optical fiber is about 1250 times the width. Because the fiber is particularly fine, has good cohesion, strong texture and delicate and soft texture, the paper made is more wear-resistant and durable.
Section 2 Types of Repair Paper
When repairing or mounting damaged paper cultural relics (books and paintings), it is often encountered how to choose paper with the same color, material, performance and thickness, which is an important factor related to the maintenance quality of paper cultural relics. Therefore, in the maintenance of calligraphy and painting, we often encounter various kinds of paper. According to their age, texture, nature and characteristics, we will briefly describe them:
First, hemp paper
Hemp paper is paper made of hemp fiber (hemp and hemp). Common are white hemp paper, jute paper, hemp paper, dry beach slope paper and so on.
Second, rattan paper
As early as the Jin Dynasty, rattan paper was produced in large quantities in Zhejiang and Jiangxi in the Tang Dynasty. Its paper is made of rattan fiber. There were white rattan paper, green rattan paper and rattan paper.
Third, rice paper.
Xuan paper is handmade paper made of Dalbergia Dalbergia bark and rice straw, named after it was produced in Xuanzhou, Anhui Province. This kind of paper is soft, white, smooth, meticulous and uniform, and its color remains unchanged for a long time. Known as "slippery as spring ice and dense as silkworm". Xuan paper is a kind of flannelette paper, which is not detailed because of its various specifications. Common ones are: ribbed paper, cotton paper, printed jade paper, single-sided adhesive paper, ten-edged paper and sandwich paper, which have been used in ancient calligraphy and painting since the Tang and Song Dynasties in China.
Fourth, cotton paper.
Cotton paper, also known as leather paper, is made of the bark of Broussonetia papyrifera, which is soft and rich in texture. Tearing from the longitudinal surface of the paper, the broken part is like silk wool, hence the name. The varieties of cotton paper vary from place to place. There are more than 20 kinds of common cotton paper, such as Henan cotton paper, Guizhou cotton paper, Shanghai cotton paper, Qian 'an cotton paper, cocoon paper, Tibetan sutra paper, Korean paper, booklet paper, Minos paper, Hua Kai paper and Taishilian paper.
Five, bamboo paper
Bamboo paper is made of tender bamboo treated with lime, which is also called "yellow paper" because of its yellowish color. There are mainly more than ten kinds of wool paper, wool paper, Sichuan paper, meta paper, straw paper and historical paper.
Six, other paper
In addition to the above kinds of paper, there are kraft paper, magnetic blue paper, tiger paper, wax paper, wool paper, gold paper and so on.
Figure 2- 1 Unearthed ancient hemp paper
Figure 2-2 Xuan Paper
Figure 2-3 Cotton Paper
Figure 2-4 Bamboo pulp paper
Figure 2-5 Old Ink
Figure 2-6 Collecting Ink
Section 3 Writing materials
The materials used for writing, printing and drawing on paper are ink, pigment, ink, ballpoint pen oil, pencil and rubber compound, which are briefly described as follows:
First, ink and ink
Ink has a history of about 4700 years in China. According to legend, ink was made after punishing foreigners at the end of the Western Zhou Dynasty. Natural graphite was used before Qin Dynasty, and artificial ink was made after Qin Dynasty. The key producing area of Chinese ink is Hanyang, Shaanxi, which was called "Rubidium" in ancient times. By the Tang Dynasty, Kuaimo was famous not only in China, but also in Huizhou ink circle at that time. There are many famous Mohists in the past dynasties, such as Wei Zhiwei's birthday, Li Tinggui in the southern Tang Dynasty, Pangu in the northern song Dynasty, Fang in the Ming Dynasty and Qing Dynasty, etc. Mo Bao of Li Tinggui, in particular, was very popular with people at that time and had the reputation of "gold is easy to get, but Li Mo is hard to find".
(1) The main raw materials for making ink are soot, animal glue and antiseptic additives.
1. Carbon ink smoke:
It is formed by collecting smoke from incomplete combustion of organic hydrocarbons. Due to the different combustion raw materials, it can be roughly divided into four types: pine smoke, lampblack, lacquer smoke and industrial carbon black. Pine smoke is made from burning pine branches. At first, the method of taking smoke was "vertical kiln", and later it was "horizontal kiln", with smoke removal as the first priority. Generally speaking, Song Yanmo is dark and lacks luster. Cooking with oil fume began in the Southern Tang Dynasty and became popular in the world in the Song Dynasty. The ancients smoked ink with vegetable oil, soybean oil, lard, soap green oil, sesame oil and tung oil, among which tung oil was used as ink, and the ink was black, shiny and enduring. In Song Dynasty, lacquer smoke was made by soaking Gu Song in lacquer residue. The lacquer smoke ink in Cheng Junfang in the Ming Dynasty has the best texture, which is made of tung oil and a certain amount of lacquer. Its handwriting is particularly shiny and quite popular. Industrial carbon black is extracted by burning mineral oil or industrial smoke, and its quality is poor.
2. Animal glue:
Animal glue is a kind of protein, which is hydrolyzed from collagen. There are many kinds of glue, such as bone glue and skin glue. The processing methods of outsole include taking materials, washing with water, soaking in lime, removing non-stick protein, pickling, boiling in water and filtering. Antler glue, swim bladder glue, Niu Pijiao, etc. It has been used throughout the ages, and its function is to make the particles of carbon ink stick together, which is convenient to make into blocks and make writing firm.
3. Anti-corrosion additives:
Its function is to prevent animal glue from mildewing and improve smell, color or viscosity. There are nearly a thousand kinds of anti-corrosion additives used by famous artists in past dynasties. Borneolum Syntheticum, Musk, Clove, Sandalwood, Gan Song, Pogostemon, Linglingxiang, etc. are commonly used for antisepsis and odor improvement. There are cinnabar, orpiment, pearl powder, gold foil, silver foil, copper sulfate, cinnabar, cortex fraxini, Sanguisorba officinalis, radix Arnebiae, madder, konjac, black beans, gallnut, walnut, cortex moutan, lavender beans, pomegranate peel, etc. It is different to add orange peel, protein and pomegranate peel to improve the viscosity and make the ink firm and not crack.
(2) the traditional ink-making procedure
Can be divided into 1. Soak in oil 2. Tobacco bowl 3. Burning tobacco. Screening tobacco. Glue 6. Drug therapy 7. Search tobacco 8. Steam agent 9. Casting 10. Weighing agent 1 1. Tempering 12. Pilling The thinner and lighter the cigarette, the better, and the older the cigarette, the more it needs to be washed and screened. Glue mixing and pestle grinding are important ink-making processes, and the proportion of glue mixing often varies with construction methods, additives and environmental climate. Should not be too heavy or too light. Too much glue is beneficial to molding and coloring, and too much glue will lead to pen lag. In ancient times, there was a saying that "100,000 pestles were too light", but the glue was too light and the pestle work was more complicated.
(3) The main raw materials of ink
The main raw materials of ink are soot, rubber, additives and solutions, which are generally machined. There are many kinds of soot, including various mineral plants and animal raw materials, which are formed by combustion or thermal decomposition. In addition to animal glue, vegetable gum (Arabic gum) or various synthetic gums such as acrylic gum and polyol resin are also used as glue. Additives include various stabilizers, penetrants, wetting agents, preservatives, essences, etc.
In contrast, the convenience of using ink is better than that of Mo Ding. However, due to the extensive use of various synthetic materials to prevent deterioration, precipitation and corruption, whether it will have adverse effects on human beings and paper cultural relics will be a problem to be further evaluated and discussed. On the other hand, China ink stick ingot is characterized by black and shiny, stable ink quality and lasting ink color. It can still be seen in ancient books and paintings for thousands of years, far from the ink of other ancient civilizations such as Egypt, Greece and Rome. The quality of China ink stick is very special, and it has been copied by other countries. /kloc-in the 7th century, French missionary Lacott said, "China ink stick is of excellent quality, and legal persons cannot copy it repeatedly. Du Hald also claimed in 1735 that Europeans tried to imitate China ink stick but failed. Therefore, China's ink is an important invention of past dynasties. It is not only used for writing and painting, printing rubbings, decorating and dyeing palaces and thrushes for women, but also used as a medicine for treating blood diseases and eye diseases. Its main feature is that it does not change color and does not fade. Whether it is the classics written by the Tang people in the Six Dynasties or the first edition of the Five Dynasties, it will still shine after 1000 years or 15,600 years. The main factor is that the chemical properties of carbon are very stable at room temperature, and the traditional gluing process has accumulated many methods, so the written handwriting is heat-resistant, water-resistant and light-resistant, and is not easy to fade, which is suitable for long-term preservation.
Second, ink.
Ink appeared with the revision of writing tools, such as the use of pens. According to the chemical properties of its raw materials, it can be divided into blue-black ink and color ink.
(1) blue and black ink
Also known as iron tannate ink, it consists of blackening component, pigment component, stabilizer, corrosion inhibitor, wetting agent and preservative.
1. Black persistent ingredient:
Mainly tannic acid (C4H 10O9) and gallic acid (C7H6O5? H2O) and ferrous sulfate (FeSO4) combine with each other to form ferrous tannic acid and ferrous gallate, which are insoluble high-valent iron after oxidation, namely ferric tannic acid and ferric gallate. The former enhances water resistance, while the latter enhances blackening, thus making the ink water-resistant, blackening and durable.
2. Pigment composition:
At present, acid ink blue and direct lake blue dyes are commonly used. Black water blue is the main color of ink, and the aqueous solution does not deteriorate in acid, but turns brown in alkali. Direct lake blue plays an auxiliary role in ink, because it contains more impurities, so it is not suitable for multi-use, and it is easy to grow mildew in wet environment.
3. Stabilizer:
The main purpose of adding stabilizer to ink is to eliminate the precipitation of ink and avoid the phenomenon of water shortage when writing. Commonly used stabilizers are sulfuric acid (HSO4), oxalic acid (COOH)2 and formaldehyde (HCHO) solution. These stabilizers have certain acidity, which lays a hidden danger for paper acidification and should not be used more.
4. boycott:
Because the stabilizer added in ink has strong acidity, in order to prevent corrosion, a corrosion inhibitor is often added to form a film with iron to reduce the corrosion effect of sulfuric acid by 90%. The iron content in the ink will not increase due to the corrosion of the pen tip, thus increasing the stability of the ink.
5. Wetting agent:
In order to prevent the water in the ink from evaporating, which makes writing inconvenient, glycerol [C3H5 (OH) 3] which is non-volatile and absorbent is added to the ink to keep the nib moist and facilitate writing.
6. Preservatives:
Organic substances and other substances contained in ink raw materials are easy to rot and mold in humid environment. In order to prevent decay, chemicals such as phenol or sodium pentachlorophenol are often added as preservatives.
(2) Pure blue ink and red ink
Pure blue ink and red ink are organic dye inks. Although their colors are bright, their handwriting is not as strong as blue and black ink, and it is easy to fade. However, red ink will fade and penetrate quickly when it meets water, so pay special attention to it.
Third, pigment dyes
Chinese painting pigments commonly used in Chinese painting can be divided into natural mineral pigments such as azurite, azurite, Chu Shi, cinnabar and alum, plant pigments such as cyanine and gamboge, animal pigments such as rouge, magenta and humiliating powder, and metal pigments such as clay gold, clay silver, lead powder and zinc titanium dioxide.
Fourth, rubber alum.
The preparation of traditional Chinese painting pigments requires alum and glue, and painting with alum silk and paper is full of color. Glue can be divided into animal glue and plant glue. Animal glue includes Niu Pijiao, deer glue, donkey-hide gelatin, bone glue and yellow croaker glue, while plant glue includes gum, bletilla glue and agar, and Niu Pijiao and bone glue are commonly used.
Alum, also known as "alum" or "alum", is made by firing alum ore. In order to protect paper silk, enhance water resistance and reduce flexibility, the painting was mounted into glue alum water and brushed on paper silk. In order to promote the uniformity of chromaticity, a proper amount of rubber alum water is added to the dye-inserted color water. Usually, one gram of glue is mixed with 60 ml of hot water at 30℃. If the glue doesn't melt after soaking for a day, simmer it and dissolve it into glue. Each gram of alum will be soaked in warm water of 10℃ in winter to form alum water, using the ratio of two grams of glue to one gram of alum. After the glue and alum water are cooled, stir them evenly with a wooden stick, and they are in proportion.
Although glue alum water can enhance the water resistance of paper filaments, alum absorbs water in humid environment, which promotes the decomposition of alum to produce sulfuric acid and accelerates the acidification of paper, which deserves attention and attention.
Chapter III Causes and Mechanism of Damage of Paper Cultural Relics
The first section internal causes
First, papermaking raw materials
The main raw material of papermaking is plant fiber, and the main chemical components of plant fiber are cellulose, hemicellulose and lignin. In addition, it also contains a small amount of tannin, pectin, resin, fat, wax, pigment, ash and other trace components.
(1) cellulose
Cellulose is the abbreviation of α cellulose, which is a compound of carbon (C), hydrogen (H) and oxygen (0). It is composed of many D- glucose groups. Glucose groups are connected with each other through β -glucose bonds, and grow into chain cellulose macromolecules. Its molecular formula is (C6H 10O5)n, where n is the number of glucose groups, which is called the degree of polymerization. The value of n is hundreds to thousands or even more than ten thousand. The degree of polymerization has a direct effect on the strength of fiber. The greater the degree of polymerization, the greater the molecular weight, that is, the longer the molecular chain, the stronger the mechanical properties of the fiber. Cellulose is white, with a specific gravity of 1.5~5.6, with optical double folding. Because cellulose molecules contain hydroxyl groups, it can absorb moisture in the air. But it is insoluble in water, which is due to the regularity of molecular arrangement and the existence of a large number of hydrogen bonds. Cellulose can be hydrolyzed into glucose in acidic medium, and nitric acid can hydrolyze and oxidize cellulose to form nitrocellulose.
Cellulose is very stable at room temperature and its tensile strength decreases with the increase of temperature. In the presence of high temperature, light and oxygen, oxidation reaction will occur, which will make cellulose produce oxidized cellulose.
Glucose at the end of cellulose exists in the form of hemiacetal, which reacts with oxidant to make cellulose react as follows:
Oh, oh.
∕
Cellulose-c10.3 hclo3 → cellulose -C +2ClO2
?
Oh, oh.
Cellulose can also undergo esterification and etherification, so that cellulose can be produced into methylcellulose, hydroxymethylcellulose and so on.
Compared with hemicellulose and lignin, the chemical properties of cellulose are relatively stable. The higher the cellulose content and molecular weight in paper, the better the strength and durability of paper. Handmade paper in ancient China has been preserved for a long time because of its pure cellulose and long fiber.
(2) hemicellulose
Hemicellulose is composed of plant cells, and xylose and galactose can be separated during hydrolysis. It belongs to a mixture of polysaccharide molecules. Include pentosan, polyethylene glycol, polydextrose and beta and alpha cellulose. Its molecule contains 200~500 hemicellulose glycosyl groups, which play a connecting role between cellulose and lignin. It differs from cellulose in that cellulose is a linear polymer, while hemicellulose contains polysaccharides with short side chains. Cellulose is a single polysaccharide, and hemicellulose is composed of more than two sugar groups. They belong to the same kind of polysaccharide, which can be esterified, etherified, oxidized, degraded and hydrolyzed under the action of light, heat, acid and alkali.
Proper hemicellulose in paper can not only shorten the beating time, but also increase the strength of paper. If the hemicellulose content is too high, it will affect the life of paper.
(3) Lignin
Lignin is one of the main components in plant fiber, which has aromatic properties and is a compound containing carbon, hydrogen and oxygen. According to chemical analysis, lignin contains the following functional groups: methoxy (-OCH3), hydroxyl (0H), carbonyl (O =C), aldehyde (-CHO), ether bond (-0-) and so on.
Lignin is white or nearly white, insoluble in solvents, fragile in texture, soluble at high temperature, and its solution is milky white or dark brown. Because lignin contains various functional groups, its chemical properties are relatively active, such as sulfonation, which makes lignin become soluble lignosulfonate and oxidized into soluble chlorinated lignin. Lignin is the most easily oxidized, especially in the presence of light, high temperature and alkali. Modern paper contains more lignin, and newsprint is easy to turn yellow and brittle, so it is not easy to keep for a long time.
It can be seen that the paper-making raw materials contain plant fibers, especially lignin, pectin, fat, pigment and other components, which has laid a potential factor for the harm of paper.
Second, the relationship between papermaking technology and paper durability
The durability of paper is not only related to the raw materials, but also to the production process. There are two production methods of paper: manual papermaking and machine papermaking.
(A) manual papermaking method
China was that first country to invent pap. /kloc-paper produced before the 0/9th century is generally called handmade paper. Handmade paper is divided into bamboo paper and leather paper. Many precious ancient books, documents, paintings and calligraphy in the past dynasties were made of leather paper. These papers have been preserved for hundreds or even thousands of years. What is the reason? This is closely related to the manufacturing process of handmade paper. With the development of the times and the progress of society, papermaking is constantly developing, revising and perfecting.
After on-the-spot investigation and analysis, Mr. Pan Jixing, with the strong support of the master of paper mill workers, made the most primitive eight-step process with China paper by means of simulation experiment:
Soaking → chopping → washing → mashing → grooving → papermaking → drying → uncovering.
The 16-step complex process of Shaanxi Fengxiang papermaking;
Soaking hemp → chopping → grinding → washing → ashing water → ashing grinding → ashing → cooking → washing → fine grinding → washing → grooving → cutting paper → squeezing → drying paper → uncovering paper.
But to sum up, the process of making handmade paper can be roughly divided into cooking, bleaching, beating and copying.
This paper is divided into four stages.
1. Cooking: Papermaking raw materials are mechanically pretreated (soaked, chopped and washed), and lime milk [Ca (OH) 2] and plant ash water are used as cooking agents in the pulping process, so as to remove the residual pigments, dirt, wax, gum and other fillers in the raw materials, so that the made paper contains calcium (calcium) instead of harmful chemicals.
2. Bleaching: The bleaching process of ancient papermaking adopted "sunlight bleaching". According to A Qing Mo Xingsan's Paper-making Theory, "Stains are exposed again after exposure. If so, yellow will turn into white. Its stains must also be tung ash and wattle ash, otherwise it will not be white. " First, the paper pulp is irradiated by sunlight, and the ozone in the air is used to produce oxidation, so that the natural pigments or coloring substances contained in valuable fibers become other genes. Then the oxidized substance is dissolved by the aqueous solution of tung ash, wattle ash and plant ash, which plays a role in bleaching. Paper made of this bleached pulp does not change color for a long time and is not easy to age and become brittle.
3. Knocking: Hu wrote in "On Papers": "If you cast it with a mortar, the more you hammer it, the more it melts, and the bones and bamboo tendons are liquid." It shows that the beating should be sufficient, and only after sufficient hammering can the paper with uniform fiber interweaving be made.
4. Paper-making: the plant fiber is made into paper pulp after the above treatment. In order to make the fibers float in the water discretely, in addition to fully stirring, some suspending agents such as Abelmoschus manihot, carambola, wild grape and phoenix tree are usually added to make the fibers evenly distributed and increase the strength.
From the above simple process, we can see that the manual papermaking process is slow, the production process is meticulous, there are few harmful chemicals left in the paper, and the fiber is not easy to be damaged, so the paper is strong and wear-resistant. At present, the paintings, calligraphy and ancient books we have seen in the Jin and Song Dynasties have a history of 1000 years. Some papers are still as white as jade and intact. These papers are all made by traditional manual methods.
(2) Machine papermaking method
Machine papermaking generally goes through the following processes: first, prepare raw materials, and then make pulp. Due to the different methods of making pulp, there are mechanical methods and chemical methods.
1. mechanical method: the fiber is dissociated by mechanical method to make mechanical wood pulp. This kind of wood pulp, lignin can not be removed, and its fiber is short and thick, containing more non-cellulose, so the paper made is loose and brittle, and it is easy to oxidize and turn yellow in sunlight and air, which is one of the factors of poor durability.
2. Chemical method is to use appropriate chemicals to remove lignin and other non-cellulose in the process of cooking raw materials, so as to dissociate fibers into pulp. According to the different chemicals used, chemical methods can be divided into sulfite method, alkali method and chlorination method.
(1) sulfite method: fiber is cooked with the mixed solution of calcium bisulfite [Ca (HS04) 2] and sulfite (HS03)2 to make sulfite chemical pulp. This kind of pulp contains a certain amount of hemicellulose and cooking liquor, and the acid that produces lignosulfonic acid remains in the pulp, so the durability of the paper is greatly affected.
(2) Alkaline method: It is a method of cooking with caustic soda (NaOH) as cooking liquid and raw material at high temperature. Because the alkalinity is too large, it does great damage to fibers, reduces the strength of paper and has high cost, so it is rarely used now.
(3) chlorination method: the raw materials are cooked with sodium hydroxide, treated with chlorination and alkali solution to remove lignin, and then bleached. In this process, sometimes alkali, sometimes bleaching powder and sometimes chlorine are used to treat cellulose, which will cause different degrees of damage to cellulose.
It can be seen from the manufacturing method of pulp that the quality of pulp is directly related to the durability of paper.
(c) Papermaking process and paper durability
From the point of view of papermaking technology, the durability of paper is also related to beating, sizing and filling.
1. The purpose of beating:
Beating is one of the important processes that determine the performance and quality of paper. The purpose of beating is to shorten the transverse cutting of fiber and make the longitudinal splitting fine. At the same time, the fiber is "hydrated" and expanded into a gel, so that both ends of the fiber are brushed, which increases the crosslinking ability of the fiber and improves the fastness of the paper.
2. The purpose of paper sizing:
To reduce its hygroscopicity. at present