What is desiccant and what does it do?
A desiccant is a dehumidifying agent which attracts moisture from the atmosphere.  It adsorbs and holds particles of water to itself.
The three most common types of desiccants are clay, silica gel, and molecular sieve.


How do desiccants work?
Performance packaging means trapping moisture around products that must be manufactured, stored, shipped, sold, or used in a dry condition. Moisture causes:

  Moisture can ruin products in several ways. Our job is to prevent moisture damage. A desiccant adsorbs moisture and we specialize in desiccants for very sensitive products that require highly-effective protection and sanitary conditions. It is important to understand how the desiccant does its job of protecting the product. Most porous adsorbents, such as silica gel, activated clay or molecular sieves rely upon physical adsorption rather than chemical adsorption to accomplish their function.  

What size of desiccants do I need?

It depends on the size of the air space to be dried, the nature of the material in the package, the moisture barrier surrounding the package, the type of desiccant being used, the desired shelf life, the atmosphere conditions where the package is sealed and stored and the type of seal on the package.
Please refer to our Desiccant Requirements Chart

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.
Can moisture be controlled inside a shipping container?

Yes. Whether shipping by sea, rail or truck, moisture and condensation can damage products while en route to their destinations. We offer a full line of solutions to help shippers control moisture in transit. To keep products dry, PDI container desiccant controls dew point, preventing condensation and container rain inside shipping containers, trailers, or rail cars.


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 dont use enough desiccant in your package to draw down the relative humidity

if the barrier material (e.g. 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.

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.  A 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 the electronic components packaging industries.  The following list shows examples of the types of industries and products that use desiccant products:



Food packaging
Pet food


Bulk powdered chemicals
Cholesterol tests
Circuit boards
Documents and paper storage
Electronic components
Glucose tests
Industrial equipment
Leather products
Medical equipment
Metal and machine parts
Metal powders
Military instruments and armaments
Museum storage
Oceanographic devices
Optical devices
Pet foods
Photographic equipment and film
Powdered or beaded glass
Pregnancy tests
Relays and communication devices

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