Desiccants - Desiccant Packs

Common Uses of Desiccants:

• Protect foods and medicines like popcorn, candy, pills, vand itamins.
• Protect important documents inside safes and lock boxes.
• Protect musical and camera equipment, electronics, leather, rubber, copper, etc.
• For moisture protection of foods, medicines and exposed electronic components, we recommend white sulfur-free Tyvek Desiccant Packets. Tyvek Desiccants are sold in same pail and drum sizes as Brown Kraft Desiccants.

Why use desiccants?

Products vulnerable to moisture damage need special protection during storage and transport to ensure that they remain effective. Desiccant Packets provide a simple, dependable and economical solution for preventing moisture damage in small, sealed packages. A popular Desiccant Packets configuration in the pharmaceutical industry, Desiccant Packets are also ideal for protecting nutraceuticals, diagnostics, electronics and food in addition to protecting products from moisture.

What are clay desiccants?

Clay desiccants are non-hazardous, moisture adsorbent substances created by the controlled drying of a calcium (bentonite) aluminosilicate clay. This naturally occurring montmorillonite clay has a special affinity for moisture and is chemically inert and non-corrosive. The layered structure of clay desiccant attracts and adsorbs moisture onto its surface and between its layers.

Clay is the least expensive of all desiccants and highly effective within normal temperature and relative humidity ranges. It is used in most industrial applications requiring humidity control. Clay desiccant can adsorb up to 28% of its weight in water vapor at 77°F (25°C) and 80% relative humidity.  At full moisture vapor capacity, Desi Pak remains dry and free-flowing. There is no apparent change in size, shape, or texture of the desiccant. 

Clay desiccant works satisfactorily below 120°F (49°C). Above 120°F (49°C), there is a possibility that the clay will give up moisture rather than pull it in (silica gel or molecular sieve are suitable for such temperatures). Accordingly, anticipated storage and transportation conditions should be considered when deciding whether or not to use clay. 

What is silica gel?

Silica gel is silicon dioxide (SiO2), an amorphous form of silica which is manufactured from sodium silicate and sulfuric acid. It is a naturally occurring mineral that is purified and processed into beaded or granular form. Like clay desiccant, silica gel is also non-corrosive and chemically inert. 

Much like a sponge, silica gel's interconnected pores form a vast surface area that will attract and hold water by adsorption and capillary condensation, allowing silica gel to adsorb about 40% of its weight in water vapor at 100% humidity.

As a desiccant, silica gel has an average pore size of 24 angstroms (24A). Silica gel desiccant will pull in moisture at temperatures up to 220°F (104°C). As temperatures increase above 100°F (38°C) the rate of moisture pick-up will slow down, but the silica gel will still work. Silica gel performs best at room temperatures between 70°F to 90°F (21°C to 32°C) and at high humidity between 60% to 90% relative humidity.

What is indicating silica gel?

Indicating silica gel is a bead or granule washed with a concentration of cobalt chloride (a heavy metal salt). The cobalt chloride is a deep blue color when dry and turns from blue to purple to pink as it becomes saturated with moisture. 

Another use of indicating silica gel is with a moisture-sensitive product that will be inspected regularly, as the indicating silica gel gives a quick visual indication of how well the product is doing. Due to the presence of cobalt chloride, indicating silica gel desiccant should never be used in contact with products for consumption, such as food or pharmaceuticals.

Indicating silica gel desiccant is also available in special packet sizes for use in electronics, pharmaceuticals, or food packaging.

What is molecular sieve?

Molecular sieve is a synthetically produced crystalline metal alumosilicate zeolite. Molecular sieve particles have a uniform pore structure (created during the manufacturing process). This enables the molecular sieve to separate molecules by size. It is also non-hazardous and derived from naturally occurring materials. 

Molecular sieve is the desiccant of choice for the most demanding and unique applications. The pore structure of molecular sieve desiccant provides a higher capacity for water adsorption than either silica gel or clay at very low humidity levels. Molecular sieve also retains a higher percentage of moisture capacity at elevated temperatures; in fact, molecular sieve can hold moisture at temperatures well past 450°F (232°C). Because of its high affinity for moisture, molecular sieve is able to bring the relative humidity in packages down as low as 10% relative humidity.

The most commonly used pore size for drying applications is 4 angstroms (4A). Molecular sieve desiccant is also available in 3 angstroms (3A), 5 angstroms (5A), and 10 angstroms (13X) sizes for specific molecule separation, including gases. 

Molecular sieve is the most aggressive of the primary desiccants (in terms of adsorption rate), so additional handling procedures may need to be considered. 

What is a desiccant "unit"?

In desiccant terminology, a "unit" is the quantity of desiccant required to meet the U.S. Military's specification (MIL-D-3464E) for packaged desiccant products. Under this specification, a unit is the quantity of desiccant which will adsorb 3.00 grams of water vapor at 20% relative humidity or 6.00 grams of water vapor at 40% relative humidity at 77°F (25°C).

When do I need to include a humidity indicator card in my package?

You need a humidity indicator card if you are concerned as to whether or not the desiccant in your package is still active. Desiccant becomes inactive under the following conditions:

if your package is not properly sealed
if you don't use enough desiccant in your package to draw down the relative humidity
if the barrier material (i.e., plastic bag) you use to package your product has a high moisture vapor transmission rate (which means that a significant amount of humid air is entering your package through the barrier material itself).
 

How does desiccant most effectively protect my product or package?

In order to achieve optimal protection, desiccants should be used within a closed/sealed moisture barrier or a rigid/sealed container. Humidity Indicator Cards are generally placed inside the container to show the humidity level and to indicate when the desiccant needs to be replaced.

What size bags, packets, and canisters are available?

Standard sizes for unit bags are as follows: 1/6, 1/3, 1/2, 1, 2, 4, 8, 16, and 80 units. One unit is roughly one ounce of desiccant material.

Standard sizes for packets are as follows: 1/4, 1/2, 1, 2, 3, 5, and 10 grams.

Standard sizes for canisters are as follows: 1/2, 1, 2, and 3 grams.

Custom sizes are available to fit your packaging needs, though such sizes typically carry a significant minimum order quantity.

What industries and products use desiccant?

The largest users of desiccants are the industrial, pharmaceutical, and electronic components packaging industries. The following list shows examples of the types of industries and products that use desiccant products:

Tyvek is a registered trademark of Dupont. / Desi Pak is a registered trademark of Süd-Chemie / Süd-Chemie is a division of the Clariant Company