How to prevent moisture in leather goods, food, and precision metal instruments

1. Optical lenses

From cameras/DC/DV in daily life; to various professional cameras/video cameras/telescopes/microscopes used in the workplace, all kinds of expensive and precise optics Instruments/equipment/supplies related to measurement, testing, investigation, health diagnosis, automated production, etc. all have lenses that can absorb moisture and become moldy.

According to Japanese photography industry experiments, the Optical Coating on precision optical lenses is prone to mold growth after absorbing moisture for a long time. Especially in environments above 60% RH, once mold grows on the lens, it is difficult to detect it with the naked eye. , even if it is sent for repair, the original sharpness cannot be restored, resulting in deviations in recording/testing/research and losses in maintenance and repurchase. Therefore, automatic humidity control is required at 30~50%RH.

2. Magnetic recording materials

Magnetic recording materials are all made of polymer materials and contain plasticizers, dispersants, etc., which are suitable for mold to decompose and absorb. Although various magnetic recording material companies have more or less added anti-mold agents in their production, the so-called "anti-mold disk" does not guarantee that the disk will not grow mold at all. It is just a difference in probability and speed. Sometimes, a disk suddenly cannot read or write, and a certain track is damaged. The main reasons are mold growth and moisture. If the magnetic recording material gets damp, the magnetic powder will fall off; if mold grows, the tape base will be eroded, both of which will cause the loss of recorded data signals. The fallen magnetic powder and mycelium can also clog the magnetic heads of computers, video cameras, and tape recorders, causing the machines to not work properly or even damaging the magnetic heads. In addition, mold can also be transmitted through the magnetic head.

Nowadays, the information recorded on magnetic recording materials is generally re-copied regularly to prevent the loss of data signals caused by moisture and mold, but this is time-consuming, troublesome, and has limitations. For example, encrypted disks cannot be copied; copying audio and video tapes will cause quality degradation. After repeated copies, the audio and video quality will be very poor and cannot meet the requirements. To ensure the safety of magnetic recording materials, magnetic recording materials should be stored in an environment with a relative humidity of about 30 to 50% RH.

3. Imaging film

Film information carriers are composed of a polymer material base and surface-coated organic photosensitive materials, which are suitable for mold decomposition. In particular, the photosensitive film on the surface is most susceptible to fungal attack. The photosensitive film of the latex layer of photographic film is also very susceptible to hydrolysis when exposed to moisture, damaging the film image. When mold grows, the oxalic acid substances secreted by the mold can corrode the silver shadow particles and dye images. Dye images will also hydrolyze themselves under high humidity conditions, and high humidity will also cause residual chemicals on the film to damage the picture. Harmful gases in the air, such as sulfides, peroxides, etc., can cause harmful effects even at very low concentrations. Peroxide is the main cause of oxidation of silver image particles, causing colloidal silver to form colored deposition spots. Others such as paint fumes and reactive compounds can damage the film base and image.

A low-humidity environment can prevent the growth of mold on photographic films and slow down the fading of image dyes. However, if the humidity is too low or the humidity changes frequently, the adhesion between the film base and the emulsion layer will be reduced, resulting in film edges peeling off, Curling, emulsion layer cracking and other phenomena. High-temperature environments will cause the film to turn gray and lose its gradation.

National standard for photographic film preservation:

Photo archive management specification GB/T 11821-89

Article 6.1.1 The appropriate temperature and humidity for preserving negatives is: Temperature 13-15℃, relative humidity 35-45%.

Article 6.1.2 The suitable temperature and humidity for storing photos is: temperature 14-24℃, relative humidity 40-60%.

Article 6.4.3 The relative humidity change between day and night in the warehouse shall not be greater than ±5%.

Storage technology of processed film security film GB 9049-88

4. Paper, wooden, silk and leather products

Paper products are widely used Used for archival materials, literature, cultural relics, calligraphy and paintings, stamps, photos and various important bills, filter paper, test paper, etc. Wood products, silk products, leather products, etc. are widely used in all aspects of life as well as artworks and antiques. They all contain a large amount of cellulose. Long-term moisture absorption will cause swelling and deformation, affecting the quality of precision printing; moisture will stick to dust and stain, react with color to cause discoloration, and interact with the stamp backing and album folders to cause adhesion. , will form water marks, mold, etc., causing the value of the item to be damaged. Chemical test strips also cannot give normal indications due to changes in their composition. Therefore, it must be stored in a relative humidity environment of 30 to 50% RH to ensure safety.

5. Tobacco, grain, tea, medicine, etc.

From home tea, coffee, milk powder, snacks, dry goods, dry food, whole grains, Chinese and Western medicinal materials, nutritious food; Medicinal ingredients, baking materials, additives in the catering industry, pharmaceutical and food manufacturing industry... These materials are very easy to absorb moisture, agglomerate, change taste, change color, deteriorate, become moldy, and even grow carcinogenic toxins (such as aflatoxin from peanuts, coffee Ochratoxin...), in terms of daily life, it affects the taste and health of food, and in terms of the industry, it will affect the quality of its products. Especially if the above-mentioned items stored in large quantities become moldy and rotten in a large area, the losses caused will be even more shocking. Storing it in a relative humidity environment of 30 to 50% RH and turning it over in time can ensure safety.

6. R&D testing supplies

Samples, reagents, standards (pieces), filters, powder materials, pure metal materials, optoelectronic semiconductor components, hardware tools, electronic parts (Materials), crystals, seeds, spices, adhesives, special sampling and sample pre-treatment supplies, precision instrument accessories/consumables, backup circuit boards... These supplies are very expensive and not easy to obtain immediately. Once they interact with trace amounts of moisture, Various possible qualitative changes will occur, which will affect the results and progress of precision research and development/testing. Therefore, it must be controlled at <40%RH for a long time to effectively solve this problem.

7. Precision metal products:

From collections of watches, precious metal jewelry, silverware, metal crafts, model cars, knives, gold coins... to industrial precision molds/tools/measuring tools /Tools/Machines (pieces)... The metal surface of precision machining (engraving) is easy to absorb moisture and oxidize (especially when above 35%RH), lose luster/rust, and be stained by dust, which affects Collection value; its precise functions may also be distorted due to aging of the machine parts, affecting accuracy or poor contact, making it impossible to operate normally. Therefore, it must be controlled at <40%RH for a long time to effectively solve this problem.

8. Precision electronic equipment

From digital electronic supplies such as DC/DV/mobile phones/MD/ipod; to R&D/Lab/engineering/process/maintenance/military and police information/education /Precision instruments/equipment/weapons/computer network management hosts/audio-visual equipment of medical/testing/computerization/audio-visual and other related units...the electronic contacts in the precision CNC IC chips/circuit boards absorb moisture and oxidize for a long time and cause poor contact, resulting in poor contact. When the machine breaks down or even goes down, its precision sensing components will deteriorate due to the interaction with moisture, causing distortion, deviation or even failure. It must be controlled at <40%RH for a long time to effectively solve this problem.

9. Precision electronic processes such as SMT/PCBA/LED/LCD/IC packaging... etc.

IPC/JEDEC J-STD-033B already strictly regulates humidity-sensitive materials/ Semi-finished products (MSD) must be stored in a fast ultra-low humidity environment (Fast Super Dryer) of <10%RH or <5%RH to prevent the occurrence of quality defects such as popcorn, air welding, peeling, oxidation, etc.

10. All scientific research industries/manufacturing industries that need to be upgraded

must improve their precision contact (closing)/pressing/mixing/injection/packaging/printing/adhesion... processing / process technology, the key materials/semi-finished products must also be MSD classified and quickly and ultra-low humidity stored as specified in 033A, in order to improve the yield rate.