Integrating ancient and modern techniques to protect the cultural heritage of wooden structures——A full analysis of ancient building wood anti-corrosion technology
Ancient Chinese architecture is built with wooden frames as the core construction system. Millennium-old buildings such as the Forbidden City, Yingxian Wooden Pagoda, and Foguang Temple have stood up despite wind and rain, and are inseparable from the wood preservation wisdom passed down from generation to generation of craftsmen. As a natural organic material, wood is easily eroded by moisture, fungi and borers. Anti-corrosion technology is the key to extending the life of ancient buildings and preserving historical context. From the traditional ancient methods of the ancients adapting to local conditions to today's modern craftsmanship enabled by technology, various anti-corrosion methods are protected layer by layer, allowing wooden ancient buildings to resist the erosion of time and continue the vitality of culture.
Traditional ancient anti-corrosion methods: natural materials, ingenious craftsmanship, and the inheritance of thousand-year-old protection techniques
In ancient times when there were no modern chemical agents, craftsmen relied on natural materials and exquisite craftsmanship to build a comprehensive anti-corrosion system, with the core centered on Material selection moisture-proof, surface protection, structure moisture-proof, natural insect repellent The four dimensions take into account both practicality and environmental protection, and many skills are still used in the repair of ancient buildings.
1. Preferably, it is a rot-resistant wood that blocks corrosion at the source
The ancients were well versed in the characteristics of wood and gave priority to wood with a hard texture, dense grain and natural corrosion-resistant properties, greatly reducing the risk of later corrosion. Nan wood and cypress are often used in buildings. Nan wood contains volatile oils and oils, and its aroma can repel termites. It has a low moisture content and is not prone to mold. Therefore, the core beams and columns of the Hall of Supreme Harmony in the Forbidden City are made of nan wood, which has remained intact for hundreds of years. Cypress wood is rich in resin, resistant to moisture and rot, and is often used for exposed components such as brackets, doors and windows. Cypress wood is rich in resin, resistant to moisture and rot, and is often used for exposed components such as brackets, doors and windows. Ancient folk buildings often use camphor wood and fir wood. Camphor wood has a significant insect repellent effect Fir is light and rot-resistant, making it suitable for the construction of ordinary houses. At the same time, the wood needs to be air-dried naturally to reduce the water content and reduce the conditions for fungal growth from the root.
2. Surface coating and sealing to form a waterproof and anti-corrosion protective layer
Painting natural protective materials is the core process of traditional anti-corrosion. The most representative is Tung oil finish With Large lacquer decoration The Committee recommends that the State party take all necessary measures to ensure that all children, including those in the family, have access to adequate health care and adequate housing. Tung oil is taken from the seeds of the tung tree. After refining, it is repeatedly applied to the surface of the wood. After drying, it forms a dense waterproof oil film to isolate air and moisture from contact with the wood, while inhibiting the invasion of borers. Ordinary wood components need to be applied 3-5 times, and important components need to be applied more than ten times to ensure that the oil fully penetrates the wood texture. Lacquer is a high-end anti-corrosion material. It is taken from the sap of sumac trees. It is natural and non-toxic. It is resistant to rot, moisture and wear. After painting, it can not only be highly anti-corrosion, but also form a warm luster. It also takes into account decorative properties. It is often used in beams, columns, doors and windows of palaces and temples. Its durability far exceeds that of ordinary coatings. In addition, the ancients would also mix lime slurry and cinnabar powder to decorate wood. The alkaline environment of lime can destroy the living conditions of insect eggs and fungi. Cinnabar has both insect repellent and decorative effects, and dual protection extends the life of wood.
3. Structural design to avoid moisture and reduce moisture damage
In addition to material treatment, ancient buildings avoid moisture hazards through exquisite structural design and indirectly achieve anti-corrosion. Universal adoption platform The design raises the wooden columns tens of centimeters to several meters above the ground to isolate the underground tidal surge; with a steeply sloping roof and eaves, it quickly diverts rainwater to prevent the wooden components from being soaked by rainwater; stone column bases are set at the column feet to block the direct contact between the wood and the ground Prevent moisture from seeping into the column; at the same time, use transparent lattice doors, windows and wall ventilation holes to maintain air circulation inside the building, reduce humidity and inhibit mold growth. The mortise and tenon structure tightens the joints, reduces wood gaps, reduces the probability of moisture and pest intrusion, and further enhances the anti-corrosion effect.
4. Natural medicine repels insects, green and harmless handguard
The ancients cleverly used natural herbs and minerals to make insect repellent. They ground mugwort, Sichuan peppercorns, camphor wood chips, or minerals such as realgar and orpiment, and then embedded them into the gaps of wooden components, under beams and columns, and inside walls. Their unique smell can repel termites and wood borers for a long time, and is harmless to humans and animals and does not pollute the environment. Some ancient buildings also place desiccants such as charcoal and lime inside the wooden components to absorb surrounding moisture, keep the wood dry, and achieve physical moisture resistance and anti-corrosion.
Modern anti-corrosion technology: technology-enabled, precise and efficient, adapted to the new requirements of ancient building cultural heritage preservation
With the development of cultural relic protection technology, modern wood preservation technology takes into account Anti-corrosion effect, protection of the original appearance of cultural relics and environmental protection and safety , upgrade and innovate on the basis of traditional processes, form three core systems: physical modification, environmentally friendly chemical treatment, and non-destructive testing and maintenance, strictly follow the principles of ancient building repair “small intervention, repair as old as old”, and adapt to the protection needs of different ancient buildings.
1. Environmentally friendly chemical anti-corrosion treatment, long-lasting antibacterial and insect prevention
Modern ancient building restoration abandons traditional toxic chemicals and adopts Low-toxic, environmentally friendly, colorless The new preservative complies with the national "Wood Preservative" and ancient building wood structure maintenance standards, and does not damage the original texture, color and appearance of the wood. It is mainly divided into water-soluble environmentally friendly preservatives (such as copper azole and isothiazolinone microemulsion) and natural extract preservatives. Through vacuum pressure, injection, spraying, injection and other processes, the drug is precisely injected into the wood. It is mainly treated on easily corroded parts such as column feet, mortise and tenon joints, brackets, etc. The drug has a long-lasting effect of up to 50 years and effectively inhibits decay bacteria and borers And environmentally friendly. For delicate small woodwork that is not suitable for large-scale treatment, such as doors, windows, and caissons, trace amounts of chrysanthemum esters are injected into the wood. There is no pungent odor and it does not affect the original appearance of the ancient building.
2. Physical modification technology to optimize wood properties
Physical anti-corrosion technology does not add chemicals, improves corrosion resistance by changing the internal structure of wood, and is suitable for the protective treatment of precious ancient buildings. Common processes include High temperature heat treatment , treating wood in an oxygen-free environment of 160-230℃, changing the chemical composition of wood, reducing water content and moisture absorption, and enhancing corrosion and wear resistance; microwave and high-frequency heating treatment, quickly evaporating the internal water of wood, while killing insect eggs and fungi, achieving the dual effects of drying and corrosion protection; in addition, acetylation treatment, optimizing the molecular structure of wood through chemical reactions, Improve dimensional stability and corrosion resistance to avoid wood cracking and deformation.
3. Non-destructive testing and precise repair, pre-emptive corrosion prevention and control
Modern cultural heritage protection introduces non-destructive testing technologies such as ultrasound, infrared thermal imaging, and radar. Without disassembling wooden components, it can accurately detect the degree of internal decay, insect infestation range, and moisture content of wood, check for hidden dangers in advance, and formulate targeted repair plans. For locally rotten wooden components, repair them by removing the rotten wood, filling them with special glue, and injecting pesticides to avoid overall replacement; for parts that are susceptible to moisture, such as column feet, treat them with sealing compresses and bandages to protect the original components and preserve the authenticity of the ancient building
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