Desiccants, which are drying agents, are used commercially in sealed packages to extend the shelf life of a product. When properly used, desiccants help keep air dry by absorbing the moisture directly from the air. Therefore, the life of a desiccant is considerably shorter in a climate with high humidity. A desiccant will only work for an extended period of time if it is used in an airtight container, such as a Ziplock bag, with all the air expelled. If you are using a container that is not airtight, like an envelope, the desiccant will become saturated in a short amount of time, rendering it useless. Most salon situations require frequent opening of the container or storage bag, making the use of a desiccant impractical. Plus, even if fungus is not actively growing, invisible fungal fragments can still live even in absolutely dry environments, and will grow when placed where moisture and food exist, such as a fingernail. So for the greatest level of sanitation, use disposable files. -- David L. Dyer, Ph.D.
The primary reason nail techs disinfect implements is to prevent the spread of bacteria, not mold and fungus. Well over 98% of all fingernail infections are bacterial. Fungal infections can occur on the nails, but they are pretty rare by comparison. Also, you will probably never see a “mold” infection on fingernails. They are much rarer than fungus.
The desiccant pouches contain a substance that acts like a tiny sponge. They absorb water and do nothing else. After one use, they should be thrown away. In my opinion, I seriously doubt they will help at all. Once an implement is properly cleaned and disinfected, you may use any type of storage container that keeps out dusts and debris. As you suggest, it is important to keep implements dry, and a paper envelope will do this by allowing moisture to escape as the tools dry. It isn’t necessary to add a desiccant. -- Doug Schoon