How to protect ancient buildings

Cultural relics protection technology is a comprehensive professional knowledge, including cultural relics production, protection, as well as prevention and control of science and technology, material properties, operational processes and a variety of surveys, testing and so on. Cultural relics in the preservation process, endured two factors of destruction, namely: ① man-made destruction. Such as ancient buildings, grottoes and temples, ancient tombs were destroyed by fire, demolished or improperly maintained lost its original appearance; copper and iron, painting and calligraphy, bamboo and lacquer ware, ceramics, etc., due to the protection of improper handling was damaged. ② wind, rain, lightning, electricity, fire, earthquake, light, pests, mold and other natural factors on the destruction of cultural relics.

China has a long history of cultural relics protection techniques, in the Tang Dynasty (618 ~ 907) on the use of wooden wedges to set right the crooked flash of ancient architectural beams recorded, and according to Huang Huofu's "Yizhou famous paintings recorded", Chengdu had relocated the three walls of the mural paintings after more than 200 years are still intact as before. Pictures and paintings to protect the unmounting technology, to the Tang Dynasty has been quite mature. "Lacquer sticking stone, swim bladder sticking wood" is the traditional technique of repairing stone cultural relics and wooden cultural relics which has been passed down for a long time. Later, with the progress of science and technology, polymer materials, physical testing technology gradually introduced to the protection of cultural relics.

Some countries in Europe in the 18th century, has been used to milk, lime water mixed with the traditional techniques of restoration of murals, has been handed down to the present.

Protection technology cultural relics protection should follow the policy of prevention first, maintenance as a supplement. Immovable cultural relics of moisture, leakage, fire, lightning, earthquake, etc., mainly relying on engineering technology to solve, while the prevention of insect pests, bird damage, etc., the main use of engineering technology and chemical treatment combined approach.

Atmospheric dust, sulfur dioxide and sulfur-containing compounds and other pollution of cultural relics exceeds the national standard, should be lifted from the source of pollution, in the national standard permits, should be greening the environment, alleviate the pollution, and at the same time, to strictly control the new addition of pollution sources.

The protection of movable cultural relics, should first pay attention to the museum library and showroom in the moisture-proof, shock-proof, mildew and other protective measures, and then on the different textures of the various types of cultural relics were protected, such as copper and iron rust, masonry and stone cultural relics of the weathering, silk and paper mildew, moth-proof, preventing aging and so on.

Repair technology wooden buildings as a whole crooked flash, prop up and set right, and then make the reinforcement treatment. Components of localized damage should be picked up, pier connection. Large components of the spoiled hollow, available unsaturated polyester resin and other polymer material infusion reinforcement, spoiled by the serious replacement of the original system.

Masonry structure of ancient buildings, the whole crooked flash, should be done first fixed point, regular observation, stabilized by the reinforcement, will no longer do foundation treatment. Cracks can be reinforced by adding hoops and grouting methods, masonry mutilations can be picked up, such as can not be picked up can be partially or completely dismantled and rebuilt according to the original. Grotto temple of the mountain fissure, using spray riveting reinforcement or grouting reinforcement, water seepage and leakage should be channeled, interception. Stone carvings, stone carvings and other stone cultural relics surface weathering application of organosilicon type of polymer material sealing.

Restoration of ancient buildings, should be able to do small repairs, not big repairs, can be partially dismantled not all dismantled, as far as possible to retain the original components in order to retain the historical value of ancient buildings. For ancient buildings with carved tile animal parts, wood carving, brick carving, stone carving and other artistic components, to be handled carefully, try to do not change or less change. On statues, murals, color paintings and other ancillary works of art, more can not be arbitrarily repaired.

Movable cultural relics of the restoration, can take the traditional techniques and modern technology combined methods, such as copper rust, can be removed mechanically or electrolytic reduction method to take away; bamboo and wood lacquer dehydration, available natural drying method, or with alcohol and ether immersion, sublimation of frozen, polymer materials penetration polymerization method; the destruction of the painting and calligraphy more than the traditional method of uncovers the mounting method of restoration; modern books and magazines can be used to strengthen the silk screen; the ancient silk screen Silk available fumigation sterilization; fragile textiles available screen reinforcement or traditional mounting method of reinforcement; ceramics broken with insect glue or epoxy resin and other polymer materials bonding.

The new materials and techniques used in cultural relics restoration must ensure that they do not harm the historical value of cultural relics, including the shape, material, color and strength of cultural relics, and at the same time reversible. The new materials used in the repair of ancient architectural components should also comply with the principle that can only be strengthened can not be replaced.

Testing technology is mainly used for the detection of traces of cultural relics residual injuries, texture and structure of the chemical composition of the analysis and age determination. Injury detection commonly used X-ray, ultrasound, etc.; texture and structure of the analysis of commonly used electron microscope, metallurgical microscope observation; chemical composition of cultural relics commonly used spectroscopy, mass spectrometry analysis; fuzzy, showing a very small contrast ink painting, etc., can be taken by infrared imaging methods; wood and other carbon-containing materials can be used to determine the age of carbon fourteen; ceramic tiles and tiles can be used to determine the age of thermoluminescence.

Preservation Techniques of Stone Cultural Relics

Preservation Techniques of Stone Cultural Relics stone cultural relics due to sunlight, water erosion, earthquakes and other natural camp force and environmental pollution, microclimate change and other factors will occur chalking, discoloration, mold, nail, alkali, cleavage, etching empty, The damage forms such as coagulation, collapse, and overturning.

Cave temple protection technology should first investigate the disease. Investigation work has the following steps: ① mapping topographic maps, cave area plan, elevation, longitudinal and transverse sections. Mapping methods are latitude and longitude instrument wire measurement, control network measurement, small plate measurement. In the elevation measurement, cave stone artwork mapping, can be used in close-up photogrammetric methods. ② Environmental quality evaluation. Including cultural relics in the mountain stratigraphy, lithology, tectonics, hydrogeological conditions, meteorological, hydrological, seismic data, sources of pollution and the hazards caused. Should point out the main hazards to cultural relics and management measures. ③ Geophysical exploration. For the solution of a special purpose, to meet the physical prerequisites and the necessary working conditions in order to achieve results. The current use of physical exploration methods are: DC resistivity method to find seepage pathways, microelectrode system method to detect the thickness of the weathering layer on the surface of the grottoes, acoustic method to measure the degree of weathering of the grottoes, seismic surveys, such as the cave before the archaeology. Stability analysis. Many grottoes are located in steep slopes, belonging to the combination of steep slopes and caves three-way space. Analysis of its stability should be from the cultural relics where the rock nature of the mountain, fissure, deformation damage process, mechanical analysis and calculation, etc., to predict the deformation damage law. For a large volume of dangerous rock should also be analyzed and calculated for the structural surface.

Preventive measures refers to the improvement of the environment in which the cultural relics, to avoid a variety of weathering stress continues to destroy. The main measures are in the grotto cliff top for seepage control and drainage, change and dredge the surface water flow direction, location and cut off the connection with the cave; find out the direction of the fissure, the scope of the surface water flow along the fissure seepage grottoes; the use of grottoes in front of the ground drainage, lowering the water table; exclude the grotto moisture condensation, preventing drastic changes in the alternation of wet and dry, etc., to prevent the water on the erosion of cultural relics. In order to avoid works of art by sunlight, rain, wind and sand direct attack, but also to build the eaves of the cave for protection.

The reinforcement of grotto temples is mainly to prevent the collapse of grottoes and the weathering of artworks.

Measures are: ① with retaining walls, retaining walls, large masonry or pouring body to stop the development of fissures, to prevent overhanging rock collapse and resist rock cracking. This method is difficult to maintain the status quo of the grotto, easy to destroy the historical remains of the cliff face, used only as a last resort. ② Spray anchor reinforcement. To different lengths of anchor rods (thick steel) using horizontal or inclined in different directions through the fissure rock body, the unstable rock body anchored in the stable rock body, and then the end of the anchor rods and fine reinforcing steel mesh welding, the surface of the high-pressure spraying of 5-15 cm thick concrete, and then use the mountain rock powder cover to do the old.

Leaving drainage holes along a certain spacing so that a small amount of seepage water can still be discharged. This method is suitable for already loose, more fissures, caves dense and broken rock grotto mountain.

It can play a reinforcing, supporting, weatherproof effect, with a large bearing capacity and safety reserves. The disadvantage is that it will locally change the external appearance of the grotto and cover up some historical remains. ③ grout bonding. For the grottoes in the carving artwork fracture, cave cliff wall cracking, collapse of one of the reinforcement protection methods. Currently used grout bonding materials are mainly epoxy resins, acrylates and inorganic chemical materials. The material performance requirements close to the physical and mechanical properties of the reinforced rock, and in line with the requirements of good adhesion, low viscosity, good irrigability, curing at room temperature, freeze-thaw resistance, water resistance. Grouting equipment is mainly used air compressor and special grouting bucket. Inspection of the grouting depth, range, rock strength, deformation characteristics, etc., to ensure the quality of grouting reinforcement.

Open-air stone cultural relics protection technology first from the study of the weathering form of stone sculpture, weathering cause classification, and then according to meteorological elements, water damage and humid environment of long-term observation and records, according to the depth of weathering of stone sculpture systematic sampling, and physical and mechanical properties of the rock test, rock oxides, chemical analysis, identification of thin section of the weathering products of the difference between the thermal analysis, X-ray diffraction analysis, spectroscopic analysis, Scanning electron microscope observation and other work, to find out the main causes of weathering of stone carvings, the use of point load strength test and ultrasonic test to detect the degree of weathering of stone carvings, and then according to the changes in the chemical composition of the rock with the depth of the means of physical prospecting, electrical and petrographic identification to detect the depth of weathering of stone carvings.

Generally more complete, weathering is not serious open-air cultural relics, should improve the protective environment. Serious weathering, no protection, can not be preserved cultural relics, only the use of protective materials. The use of protective materials should be clear mainly to prevent which kinds of weathering camping force, the proposed protection should be achieved after the main indicators, and requires that the material is colorless, transparent, non-reflective, not crispy alkali, chemical stability, penetration ability, with the ability to resist weathering, a certain solidification strength and so on. Generally used protective materials are polymer organic polymerization materials (silicone, polyurethane, methacrylate, silicone, etc.) and inorganic chemical materials.

In order to the safety of cultural relics, it is necessary to be careful about the performance of the stone protective layer of material testing, including: ① protective layer of material form, filling degree and changes along the depth direction; ② physical and mechanical properties: such as porosity, permeability, consolidation strength, abrasion strength, etc.; ③ resistance to water erosion: such as the surface water absorption rate (capillary water absorption), the maximum rate of water absorption, hydrophobicity, Water permeability, water permeability, etc.; ④ weathering resistance: such as aging resistance (including artificial aging test and natural exposure field), freeze-thaw test, stability test, wet and dry alternation test, etc.; ⑤ chemical stability: such as resistance to acidity, soluble salts, in the content of soluble salts, resistance to contamination, etc.; ⑥ recoating: the possibility of providing protection for future generations.

The collection of stone cultural relics protection technology from the tomb or from the field into the museum collection of stone cultural relics need to surface descaling, remove contained in a variety of salts or microorganisms. The main methods are: ① remove soluble salts. Generally in running water for a longer period of time, and then use deionized water. Volume of stone tools, can be coated with paper pulp, after drying uncovered. ②Surface descaling. Into the ultrasonic cleaner, quickly wash away. Marble rust shells can be used to seal around the dimethyl resin with dilute acid corrosion of the rust, and then mechanically removed. Other stoneware can be softened with dilute acid to dissolve the dirt, and finally washed with non-ionized water. ③ bonding repair. Bonding materials are generally used in epoxy resin class mixed with a small amount of pigment mixed into the stone powder adhesive, can also be used in nitrocellulose or polyvinyl acetate class bonding weathering serious stoneware. Has been quite loose or painted surface stone artifacts, bonding before the selection of methyl acrylate and polymethacrylic acid butyl ester, polyester acid vinyl ester, epoxy, organosilicon and barium hydroxide and other materials for penetration reinforcement. Repair materials commonly used in cooked gypsum plus cellulose, acetone and amyl acetate mixture with 10% celluloid solution and then adjusted to fine stone powder, polyvinyl acetate emulsion to join the rock powder and amorphous silicon dioxide, the pigment will be adjusted into a paste for repair.

Restoration Techniques of Grotto Paintings

Restoration Techniques of Grotto Paintings grotto murals are generally in the cave after excavation, in the uneven stone walls on the first layer of grass and mud, and then painting. Northern Wei, Western Wei, Northern Zhou period of the mural battle, more than smearing wheat grass mud two layers, do not paint the base color, directly in the rougher mud wall coloring for painting. Ground battle between the grass and mud layer and the pigment layer and the grass and mud layer combined with each other more closely, generally does not produce peeling lesions, but the local wall will have small cracks appear.

Tang and song dynasty fresco mud layer is generally 3 to 4 layers, the mud layer type increase, in addition to wheat grass mud layer, there are hemp knife, cotton, cattail and other mud layer. Before applying color painting, first in the surface of the ground battle brush a very thin layer of white powder. This white powder painting layer will produce cracked skin and scale-like flaking, generally known as cracked armor lesions. When the moisture is serious, together with the ground battle mud layer together with flaky, known as crispy powder lesions.

Some of the frescoes on the ground battles mud layer is too thick or descendants in the previous generation of frescoes on the repair of heavy frescoes, due to humidity, earthquakes, rock fissures and other impacts, part of the ground battles with the rock wall detachment, the formation of fissures and drums, frescoes at any time, there is a risk of large-scale fall off.

Five Dynasties period there is a production in the cave outside the rock face of the mural, also known as open-air mural. The ground battle is in the rock wall first smeared grass mud two layers, and then smeared with hemp knife lime paste layer, there are also directly smeared lime paste on the rock wall, and then apply color for painting. This kind of lime ground battle will also appear hollow drum or small area detached from the rock lesions.

The repair method of the above lesions are as follows:

1) mural white powder painting layer cracking armor lesions repair method. First remove the armor white powder painting layer inside and outside the dust and sand, to the armor white powder painting layer and the mud layer between the injection volume ratio of 4:1 2.5% polyvinyl alcohol water solution and 1% polyvinyl acetate emulsion prepared by the mixed adhesive, the white powder painting layer back to the ground battle, and then outside the package white silk cotton pat compaction, and so injected into the white powder painting layer of the internal adhesive in the water collection, and then to the surface of the mural paintings sprayed once volume ratio of 4:1 1 1.5% polyvinyl alcohol solution and 1.5 percent polyvinyl acetate emulsion prepared by the adhesive, and the volume ratio of 4:1 1 polyvinyl acetate emulsion. 1 of 1.5% polyvinyl alcohol water solution and 1% polyvinyl acetate emulsion mixture. If there is a lesion missing place, there will be bubbles after spraying, can be injected again adhesive repair. To be sprayed slightly dry, the white silk on the surface of the fresco, with a soft rubber rollers universally and evenly rolled once into. With this method of restoration of the mural color without damage, no glare, can maintain the original appearance of the mural, the agent is reversible, does not affect the restoration. China Dunhuang Mogao Grottoes more than 1,000 square meters of cracked armor mural is the success of this method of restoration, has been subjected to the test of 25 years, did not restart armor.

② mural mud layer crispy powder lesions repair method. With the white powder painting layer cracking nail repair process is basically the same, just according to the object to the mud layer deep injection of different concentrations of aqueous polyvinyl alcohol and polyvinyl acetate emulsion mixture or simple polyvinyl acetate emulsion, as well as acrylate emulsion, and then compacted.

3 mural battle detached from the rock and painting wall drum repair method. Mural part of the grass mud ground from the rock body, the first edge of the brush a layer of polyvinyl acetate emulsion, and then 15% polyvinyl acetate emulsion, clay, sand, hemp knife or wheat grass into a paste, to the edge of the ground into the battle, so that the wall of the paintings and the rock body firmly affixed. In order to make the restoration and mural tone consistent, can be added to the mud inside the appropriate pigment.

The wall of the painting of a large area of drums, can be used pressure grout (adhesive) paste or take grout and riveted combination of repair methods.

Lime wall murals small hollow drum, can be soaked in epoxy resin or polyvinyl acetate emulsion gauze strips from the wall breaks into the ground between the battle and the rock hollow drum part, uniformly applying the appropriate pressure, so that the painting wall and the rock body tightly, to be dry and solid after the adhesive can be glued. Painted wall breach with 15% polyvinyl acetate emulsion sand and lime paste to fill. Before filling also to the edge of the wall to smear a layer of polyvinyl acetate emulsion. This will not only make the bond more firmly, but also to avoid the lime paste in the moisture seepage to the surface of the mural, leaving stains.

Preservation and Repair Techniques of WallPaintings in Ancient Buildings and TombsAncient buildings and tombs mural paintings should be protected in situ in general, and in special cases, they can be relocated for protection.

In-situ protection in the reinforcement of murals, but also need to improve indoor ventilation, moisture, sun protection facilities. Tomb murals are mostly used after reinforcement in natural conditions closed preservation, mural reinforcement methods according to the damage.

When the picture serious degumming, with 2 ~ 3% glue alum water or 2 ~ 5 polyvinyl butyral and other polymer materials sprayed 1 ~ 2 times. Picture surface skin crispy alkali reinforcement agents and degumming treatment is the same, but the concentration of the agent increased, the number of times the spraying increased. When the mural surface layer is thin and brittle, the inner layer of crisp alkali, need to use the method of needle injection, the same agent and degumming treatment. Work to be a square inch by square inch piece by piece, the number of injections depending on the picture, the agent used should be thin and then thick.

When the mud layer of the mural drums, the application of dry mud riveted. In the picture without lines, drilling small holes in each square meter 2 to 3, with white ash or sand mixed with polyvinyl acetate emulsion or polyvinyl butyral, made of dry hard ash or clay bar squeezed into the holes, the mud layer of the frescoes and the wall adhesion; serious cracks, with the same dry mud material squeezed into the cracks and adhesion. Part of the picture fall off place according to the original fresco mud layer practices to make up for the smooth, painted color for the old.

Migration and protection of the three steps of uncovering, repairing and installing.

Reveal the fresco and the wall complete separation, fresco area can be small single piece of reveal, large area to be divided into pieces of reveal, each piece of 1 to 3 square meters is appropriate; picture height of more than 2.5 meters need to be divided into upper and lower two layers or three layers of reveal.

Reveal before a series of preparatory work should be done, mainly mural copying, mural and wall structure of the investigation, drawing the uncovering of the mural block number size map, block relationship size map. Then according to the size of the block, frescoes and wall structure to determine the uncovering method. Commonly used methods are as follows:

①Tear down the wall to take. First in the picture with 40% peach glue solution or 10-20% polyvinyl butyral full paste a layer of white gauze to protect the picture. After drying by the screen to install the front wall plate and remove the table. With a knife saw saw the wall board on all sides of the edge of the seam, the seam width of 5 ~ 8 mm, and then in the back of the mural from top to bottom in sections to remove the wall blocks, each section is 50 ~ 70 cm high. Close to the bottom edge of the need to quickly turn the front wall plate, along with the mural mud layer inward push down, flat on the uncovering table.

Transported to the restoration room to be repaired.

② sawing. When the murals have more than two layers of mud, the thickness of more than 2 centimeters with a saw blade to the mud layer and the wall sawing.

3 pry. When the mural mud layer bulging, with a flat shovel to pry the mural away from the wall.

4 vibration. When the fresco local mud layer and the wall solid adhesion, with an iron drill in the mud layer and the wall between the light chiseling, mainly by vibration to make the fresco away from the wall. Sawing, prying and vibration, often in the same block of paintings in the unveiling of the mixed use.

⑤Set take. When the fresco is earth wall wall, can be used wooden box set take.

In the front wall of the four sides of the nail board into a box, embedded in the soil wall will be set into the box mural, and then sawing the soil wall so that the mural left the wall.

6 sticky take. When the mural painted directly on the brick wall or stone wall, available adhesive tape. Coated with 10 ~ 15% polyvinyl butyral and other polymer materials, white cloth, pasted on the screen, so that the color layer of frescoes adhere to the adhesive tape, dry after removing the tape, frescoes with the tape will be removed down.

Repair the mud layer of frescoes, repair should be the back up, with a small shovel to remove the mud layer at the bottom of the frescoes, retaining the surface of the frescoes of the mud layer, with 2 ~ 5% gum alum water or polyvinyl acetate emulsion and other polymer materials, spray 1 ~ 2 times to strengthen, strengthen the agent can not penetrate into the surface of the frescoes. After drying, make up the new mud layer, together with the thickness of the surface layer is generally 1.5 to 2.5 centimeters. The new mud layer of the material ratio and the surface layer of the same, with white ash or sand mixed with insect glue or polyvinyl alcohol and other polymer materials and systems. Then use epoxy resin to paste a layer of gauze shockproof. The back of the final epoxy resin glued into the bottom bracket to support the mural, the style of the cross format of the wooden cabinet or light metal cabinet. The cabinet is reserved for the installation of the iron live eye. After the back is repaired, reverse the wall upward, in addition to gauze, remove the residual glue, the residual damage with raw materials to make up a flush, to be installed after the unified color.

When using adhesive tape to take no mud layer mural, should first be made according to the size of the painting piece of bottom bracket, the face of the nail plate imitation of the original wall color brush for the old, and then the adhesive tape has a painted side of the bottom bracket on the flat plate, and then with the adhesive material diluted solvent will be the adhesive tape brushed wet, and gently uncovered adhesive tape, so that the mural of the color layer to stay in the bottom bracket on the flat plate.

Installation Museum display of small murals or by several pieces of frescoes, only in the back of the repaired murals, installed on the support suitable for visiting can be.

Installed in the original building in the original location, should be based on the structure of the building, the wall above the shoulder to install hanging frescoes of wood or metal brackets. Walls with paintings on one side with a single-sided bracket, two sides with paintings on both sides with a double-sided bracket. Bracket is composed of a number of columns and lateral braces, columns need to be firmly connected with the building frame, and then according to the numbering sequence, a wall, a wall for installation. First of all, the back of the mural bottom bracket with iron work and bracket of the brace connection, at the same time with the mural chunks of the relationship between the size of the map, repeatedly check the correctness of the iron work, and then fixed.

Installation should also consider the mural of moisture, ventilation, the bottom of the wall should be added to the moisture layer. On the side of no painting to build a thinner solid outer wall, the outer wall and the bracket between the gap of 5 to 10 centimeters, can make the back of the mural ventilated; important mural installation, this section of the gap is generally not less than 50 centimeters, in order to prepare for the staff to enter the inspection of the safety situation.

Finally by the art workers to patch the saw kerf between the paintings, and according to the copy of the line coloring, restore the original appearance before the uncovering.