The preservation methods of fingerprint collection kits are crucial as they directly affect the integrity and usability of the collected fingerprints. 

The following are the preservation methods for different components of fingerprint collection kits:

Fingerprint Powder

• Dry and Sealed Preservation: Fingerprint powder should be stored in a dry and cool environment to prevent moisture absorption and caking. It is usually stored in a sealed container, such as a plastic or glass bottle with a tight – fitting lid. This way, the powder is kept from coming into contact with moisture in the air, maintaining its good fluidity and adsorption properties. For example, black fingerprint powder may harden into lumps when exposed to moisture, affecting its even application during fingerprint collection and, subsequently, the visualization of fingerprints.
• Avoid Direct Sunlight: Ultraviolet rays in sunlight can cause chemical changes in fingerprint powder, reducing its ability to adsorb and develop fingerprints. Therefore, the containers holding fingerprint powder should be placed in a shaded area, such as in a cabinet or drawer, to prevent direct sunlight.

Fingerprint Brushes

• Clean Before Storage: Fingerprint brushes should be cleaned promptly after use to remove any remaining fingerprint powder and other impurities from the bristles. The bristles can be gently washed with a mild detergent solution, then rinsed with clean water, and dried with a clean towel or tissue.
• Maintain Bristle Shape: After cleaning, the fingerprint brush should be left to dry naturally in a well – ventilated area. Avoid using high – temperature devices like hair dryers to dry it, as this may damage the bristles. Also, when storing, pay attention to maintaining the shape of the bristles. The brush can be hung up or placed on a specialized brush holder to prevent the bristles from deforming, which could affect its performance in subsequent use.

Lifting Tape

• Preserve in Original Packaging: Lifting tape should be kept in its original packaging to prevent contamination or damage to the tape surface. The original packaging usually provides better protection, preventing the tape from coming into contact with other items and losing its stickiness or picking up dust and other impurities.
• Avoid High Temperatures and Humidity: High temperatures can change the stickiness of the tape, causing it to lose its good lifting effect. A humid environment can make the tape damp, affecting its adhesion to fingerprints. Therefore, store the lifting tape in an environment with relatively stable temperature and humidity, away from heat sources and moisture sources. For example, avoid placing it near windows, air – conditioning vents, or water pipes.

Fingerprint Cards

• Store Flat: Fingerprint cards should be placed flat in a dry and clean location to prevent squeezing or bending. They can be placed in a folder or card box to keep them flat and avoid damage to the fingerprint patterns due to card deformation, which could make the fingerprints difficult to identify.
• Avoid Contact with Chemicals: Fingerprint cards should be kept away from contact with chemicals, such as ink, cleaning agents, and organic solvents. These substances may contaminate the fingerprints or damage the coating on the card surface, thereby affecting the quality of fingerprint preservation. Therefore, the area where fingerprint cards are stored should be kept away from chemical storage areas.

Chemical Reagents

• Store According to Requirements: Different chemical reagents have different storage requirements, and they should be stored strictly according to the reagent instructions. For example, ninhydrin reagent usually needs to be stored in a cool and dry place with good sealing because it is sensitive to humidity and oxygen. Exposure to moisture or air may reduce its reactivity.
• Separate Storage: Various chemical reagents should be stored separately to avoid mixing or chemical reactions between them. A specialized chemical reagent cabinet can be used, placing different types of reagents in different compartments or drawers, and clearly labeling them with information such as the reagent name, composition, storage conditions, and expiration date to prevent misuse.

By using the correct preservation methods, the performance and quality of each component of the fingerprint collection kit can be ensured, thereby providing reliable support for fingerprint collection, preservation, and subsequent analysis, and enhancing the application value of fingerprints in fields such as criminal investigation and security.