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Every country will have its own national museum, which displays and preserves a large number of various cultural relics. However, with the prolongation of time, the problem of destruction and damage appeared in various cultural relics to varying degrees. The cultural relics showcase is the most basic equipment in the display equipment. Its function is to package and display cultural relics. Through the cultural relics showcase, the museum directly and silently communicates with the audience. At the same time, the cultural relics display cabinet is also the last line of defense to protect the safety of cultural relics. Any cultural relic is a non-renewable resource. As a cultural relic protector, we should pay attention to preventing hidden damage to cultural relics exhibits such as microbial erosion and relative humidity, air pollution, light and heat.

1. Requirements for the protection of cultural relics

(1) Temperature and humidity

When carrying out research on the environment of cultural relics, the most basic work is to measure temperature and humidity. These two factors will have a direct impact on all physical, chemical, and biological functions, and even play a decisive role. Under certain conditions, temperature and humidity affect and interact with each other. When the temperature changes, the humidity will also change accordingly, and then the temperature and humidity jointly affect the photooxidation rate of cultural relics. As we all know, fiber cultural relics will change their structure under the action of light, such as the color change of dyes, and the result of this change is the result of photochemical reaction. The photooxidation rate is closely related to the humidity. When the humidity is very high, the photooxidation will increase rapidly, and the degree of light damage to textiles and dyes will be enhanced. Relatively speaking, metal cultural relics are more susceptible to the influence of temperature, a typical example is "bronze disease". The reason is that under high humidity conditions, metal cultural relics are prone to chemical reactions with moisture in the air, causing harmful rust to form, which seriously affects the life and safety of cultural relics. Moisture is a necessary condition for the growth of microorganisms and bacteria. The higher the humidity in the environment, the more conducive to the growth and reproduction of microorganisms and the spread of mold. During the growth of mold, enzymes will be produced. Under the action of enzymes, the speed of hydrolysis of cellulose will be accelerated to form hydrolyzed cellulose. Under the influence of hydrolyzed cellulose, the strength of organic cultural relics will be greatly reduced, and pigments will fade or change color. The generally accepted standard values for museum indoor temperature and relative humidity are 14°C-24°C and 45%-65% relative humidity. Ideally, the temperature and humidity should be kept constant, but this is impossible and impossible in reality.

Under normal circumstances, when the temperature and relative humidity fluctuate slowly within this value, the increase rate should be minimized, which is suitable for the preservation of cultural relics. In the subtropical regions of my country, when the rainy season comes every year, the air humidity exceeds 80%, and the relative humidity requirements for the display cabinets are strict. Considering the cost of capital investment, electronic constant humidity machine and silica gel agent can be used in two ways. The imported electronic hygrostat is controlled with an accuracy of +/-5%RH. The equipment is installed in the base at the bottom of the showcase, and the humidity detector is installed in the middle of the vertical panel on the side of the showcase to provide accurate humidity in the cabinet. Set the corresponding humidity according to the different cultural relics in the showcase. The electronic constant humidity machine is fully capable of controlling the relative humidity in a small environment to meet our basic requirements. Another way is to use silicone medicine, which is placed in a container made of steel plate, which is installed in the base at the bottom of the display case. At present, these two methods can effectively adjust the relative humidity and have the function of filtering polluted air and dust. As far as the effect is concerned, the humidity control of the electronic constant humidity machine is obviously better than that of the silica gel agent, and the humidity control is more stable and accurate, but the cost of the electronic constant humidity machine is much higher than that of the silica gel agent, and the daily maintenance is also more troublesome. The electronic constant humidity machine needs regular maintenance and cleaning. The fan inside the machine works for a long time, is easy to wear, and makes a lot of noise, which seriously affects the quality of tourists' visits. The humidity conditioner can effectively control the relative humidity in the display cabinet, and has the advantages of low cost, easy to use, and less maintenance. The practical value of research and development of the humidity conditioner is very extensive. In terms of temperature control, the central air conditioner is mainly used to regulate the large environment temperature of the exhibition hall, and the temperature of the entire exhibition hall is kept at about 20°C.

(2) Lighting

In the preservation and display of cultural relics, in addition to temperature and humidity, the basic work also includes light, which is an external environmental factor that is often faced in the study of cultural relics protection. There are two main sources of light radiation: one is sunlight; the other is artificial light. Either way, it will damage the preservation of cultural relics to a certain extent, especially ultraviolet light. Under the influence of light, cultural relic materials will generate thermal energy, which accelerates the speed of related chemical reactions, especially photochemical reactions. Studies have shown that light can destroy all organic material artifacts, cause surface deterioration, and accelerate the rate of deterioration. However, for inorganic material cultural relics such as stone cultural relics and metal cultural relics, the direct damage effect did not appear obviously. When light destroys cultural relic materials, chemical deterioration is the main destructive effect, leading to the aging of cultural relic materials. In order to minimize the impact of this kind of aging and deterioration, corresponding measures must be taken, and the light should be effectively controlled. Consider the light intensity, lighting time, radiation composition, etc. of the cultural relics to ensure that the damage to the cultural relics exhibits is minimized during the exhibition. Fiber optic lighting is a high-tech that began to be applied in the 1970s. Optical fiber lighting is a cold-light lighting system without ultraviolet light. The optical fiber and the optical fiber terminal only transmit light. When some showcases need background lighting at the same time, fluorescent lamps can be installed on the top of the showcase, and special glass and grids that can isolate ultraviolet rays and achieve uniform light effects are used to separate the lamp tubes from the air conditioners in the exhibition area, so as to isolate ultraviolet rays and the emission of the lamp tube itself. heat.

In the exhibition design of museums, when part of the natural lighting is used, it is an important breakthrough in energy conservation and environmental protection, but the ultraviolet radiation in natural light can not be ignored on cultural relics. The entry point to solve this problem should be showcase glass. For ordinary glass, if the ultraviolet wavelength does not exceed 320nm, it can be filtered out, but when the ultraviolet wavelength is 320~400nm, it cannot be filtered out and can still pass through. At this time, anti-ultraviolet measures must be implemented. Ultra-white laminated glass, in the middle is PVB film that can isolate ultraviolet light, which can isolate more than 99% of ultraviolet light, which can effectively prevent ultraviolet light from damaging the cultural relics exhibits in the cabinet.

(3) Harmful organisms and harmful gases

Under the influence of the materials used to make the display cabinets, the environment in the cabinets for preserving the cultural relics exhibits is relatively safe, which can avoid biological and air pollutants from damaging the cultural relics exhibits. The material of the showcase must be well grasped. The materials used must not cause damage to cultural relics, have good waterproof and fire resistance, are not easy to breed insects, and need to undergo strict insecticide and disinfection treatment; they should conform to environmental protection. Because the display cabinet will directly or indirectly contact the cultural relics, if chlorine, sulfur or other acidic components exist in the display cabinet materials, the cultural relics will inevitably be damaged. The internal decorative panels must be made of E0-grade green environmental protection MDF. The boards are firstly treated with anti-virus and insect-proof, and then sealed with Moistop, and the outer surface is bonded with 100% pure cotton textile items. These must pass the test to allow products used in museum showcases. In this way, good air quality is provided, and the pollutants generated by the environmental materials in the showcase are prevented from damaging the cultural relics.

2. The design requirements of the showcase structure

For cultural relics display cabinets, there are double requirements, that is, they must be able to preserve cultural relics well and be easy for the audience to watch. Therefore, in addition to having a solid structure, the display cabinets also need to meet the following requirements.

(1) Air tightness

Air tightness is one of the important parameters to measure the quality of a showcase. When the airtightness is good, a relatively stable storage environment is provided, which is more beneficial to the protection of cultural relics. If the sealing is not good, it cannot meet the requirements of constant temperature and humidity at all, and cannot guarantee the air quality in the showcase. However, the display cabinet not only needs to be sealed, but also sometimes opened. As a result, the airtightness requirement is more difficult to achieve. In order to truly meet the airtightness requirements, non-permanent sealing facilities must be selected, and metal and glass structural materials should be used, and permeable wood and plastic materials should be avoided. The airtightness of the showcase is closely related to its processing technology, the higher the processing technology, the better the airtightness of the showcase. Here I introduce the materials used for sealing, which can be used for reference. The seal on the fixed parts of the showcase can be sealed with imported Dow-Corning environmentally friendly neutral structural adhesive that does not contain any acidic substances, which not only ensures environmental protection, but also ensures the sealing and bonding strength; the movable part of the showcase is sealed It is realized by the sealing profile and the ultra-thin sealing strip made of silicone material.

(2) Safety technical requirements

The display cabinet must be solid, durable, have sufficient shock resistance, bearing capacity and considerable mechanical strength, and will not break or fall apart when subjected to external forces, and will not affect the safety of the stored cultural relics; for fragile exhibits, the display cabinet must be shockproof, Anti-vibration and anti-slip measures; the auxiliary support plate and fixing card of the showcase must be firmly fixed; the fireproof performance is required by the showcase material itself; the anti-theft function should also be equipped in the showcase, and more than two lockholes for the showcase door should be installed, and the management of two keys It is carried out by two managers respectively; the alarm device is installed inside the showcase, and there are two types in total, one is a vibration alarm and the other is a glass breaking alarm device; closed-circuit television monitors also need to be installed; laminated glass is used as a showcase Glass enhances the impact resistance of the showcase.

(3) Operating technical requirements

The operation and practical technology requires that the door of the display cabinet should be flexible, the opening of the sliding door should be reasonable, and the account opening device should be safe and firm; the design of the door of the display cabinet should be convenient for taking and placing cultural relics; the location of the power socket should be hidden, convenient and reasonable; the mechanical device for opening the display cabinet It is hidden, firm and durable, and the base design can be adjusted horizontally; the box of hygroscopic buffer material should be placed on the lower layer of the showcase, and the convenience of replacing the hygroscopic buffer material should be fully considered during design; the maintenance and repair of the showcase is convenient and simple. The door opening technology of the showcase is also one of the signs of high-tech content. At this stage, there are many ways to open the common showcase doors, such as extractive opening, rotary opening, sliding opening, etc., which can be selected according to the actual situation.

(4) Appearance of the showcase

The cultural relics showcase is an object that directly communicates with the audience and provides a space to display cultural relics in a real artistic shape. Aesthetic visual effect technology requires that the appearance of the showcase should be beautiful and generous, with uniform color, harmonious and consistent with the display design of the entire environment, and always grasping the cultural relics is the most eye-catching highlight. Because children are among the audience who watch the cultural relics exhibits, the viewing needs of children must be fully considered. The glass of the showcase should have a wide field of vision, and the safety film or ultraviolet filter film should be pasted between the double-layer glass. It is not allowed to stick film on the outer glass, because it will cause scratches during the exhibition. Colorless ultra-white glass should be used as the glass used in the showcase, and the light transmittance should be above 92%. The glass of museum showcases is not suitable for glass containing iron to avoid color distortion. In the case of iron, the color of the glass will appear green or blue, which will affect the viewing of cultural relics and cause distortion of cultural relics. If economic conditions permit, choose low-reflection ultra-white glass to eliminate unwanted reflected light on the outer surface of the showcase glass.

At present, there is no uniform standard for the protection of cultural relics in the cabinets in various museums. Whether it is the air exchange rate, lighting in the showcase, or the environmental protection performance of the production materials, load-bearing coefficient and other issues related to the protection of cultural relics, some museums have not put forward strict and clear requirements, which will inevitably have a negative impact on the cultural relics on display. It is directly related to the life of cultural relics. It is hoped that the technology of cultural relics display cabinets will continue to innovate and progress, and open a new chapter in the protection of cultural relics.