How To Use Desiccants

Moisture causes serious problems for many kinds of products, from pharmaceuticals to leather goods. A desiccant product such as silica gel can help. These handy packets adsorb extra moisture to keep things fresh and prevent damage during shipping and storage.

What Is a Desiccant?

Desiccants are materials that absorb or adsorb moisture from the air. Also known as drying agents, they are used to keep things dry in shipping or storage and prevent moisture damage. The most commonly used desiccant material for shipping, packaging and product protection is silica gel. Silica gel works by adsorption, meaning water molecules in the air are attracted to the surface of the material. Silica gel beads contain many microscopic pores that increase the surface area for attraction and hold onto the water molecules.

What Are Desiccants Used For?

A silica gel desiccant is used to reduce the humidity level in a closed environment and protect products from moisture damage. They can be packed inside product packaging or placed in the shipping box when materials are mailed. They are used when storing, shipping or mailing items that are sensitive to moisture. Some of the most common uses of desiccants are:

• Pharmaceuticals and nutraceuticals
• Electronics and camera equipment
• Dry foods and pet foods
• Clothing, handbags and leather goods
• Silverware, jewelry and metals
• Seed storage
• Cosmetics
• Books, documents and paper goods
• Artwork

Many people save silica gel bags for uses around the home, too, such as preserving dried flowers or tossing them in a sweaty gym bag. Anywhere moisture is a problem, a desiccant can help.

How Do You Use Desiccants?

Passive desiccants like silica gel are easy to use! Silica gel packets are ready to go and do not require any activation. Just toss one or more into the package before you seal it up.

Why Do I Need a Desiccant?

Moisture can come from the air around us (humidity) or from the materials being stored. Many products and materials—including electronics, leather goods, foods and pharmaceuticals—are sensitive to humidity in the air. The desiccant material takes up excess moisture to keep humidity levels in the package within the acceptable range for the product and prevent product damage. Other products may contain moisture that seeps or sweats into the package, raising interior humidity levels. A desiccant can help with this problem, too. By controlling moisture levels inside the package, silica gel packets protect products from mold, rust, microbial growth and other problems created by moisture.

What Are the Advantages of Silica Gel Packets?

Silica gel packets are low-cost, easy to use, and highly effective. Silica is one of the most abundant elements on Earth, making it highly accessible and cost-effective. Under normal conditions, silica gel will provide protection from moisture for many months, making them ideal for both shipping and storage. Silica gel can absorb up to 30% of its own weight in water while remaining effective.

When Should Silica Gel Packets Not Be Used?

Silica is best for use in normal atmospheric temperatures and humidity levels. They may not perform as well in extreme temperatures (especially high temperatures) or with very high levels of moisture. Other types of desiccants or adsorbents, such as calcium chloride, may be needed if you are dealing with high levels of moisture or liquid water that needs to be removed.

How Many Silica Gel Packets Do I Need?

The number of silica gel packets you need depends on:

• The volume of space to be desiccated
• The amount of moisture in the air
• How long protection is needed
• How dry the air needs to be

Silica gel packets are sized in “units.” For example, a small silica gel packet is 1/3 unit and a large silica gel packet is 2 units. As a general rule of thumb, 1.2 units of silica desiccant will protect up to 1 cubic foot of space inside the package for standard shipping and storage conditions. 

How Long Do Silica Gel Packets Work?

Silica gel packets are usually good for between 4 and 12 months, depending on how much moisture is in the space. After this, they will need to be recharged or replaced. However, in a sealed low-humidity environment, unused silica gel packages can be stored much longer—potentially indefinitely, if they are not exposed to any moisture. If you are not sure if your silica gel packets are still good, they can be recharged.

Can Desiccants Be Recharged?

Yes, most desiccants can be recharged and reused, though in practice, silica gel packets are usually thrown away by consumers when the package is received. Silica gel packets can be recharged in the bag by heating them to 245°F for 16 hours. Do not overheat; this will damage the silica gel and, at high heat, can set the paper packaging material on fire. Low and slow is the key to recharging desiccants!

Is Silica Gel Toxic?

By itself, silica gel is non-toxic—but those bags are marked “Do Not Eat” for a reason. Silica used for desiccant purposes may contain traces of other materials which may be toxic. In addition, the silica gel will dehydrate tissues in the body, which may cause irritation to mucus membranes in the nose and throat, stomach pains, vomiting and constipation. Silica gel can also cause choking or an intestinal obstruction as it adsorbs water and swells in the body. Keep silica gel packets out of the reach of children and pets and contact a health professional if they are swallowed.

What’s the best desiccant for your needs? Talk to a Benchmark representative to find the right desiccant for your application.