There are 3 common types of desiccants and the use of desiccants is a smart preventive measure for the proper protection of products from moisture.

1. Types and Uses of Desiccants
A desiccant is a substance that absorbs water vapor from the air. Typically used in the
packaging industry, desiccants are used to eliminate the harmful humidity that could
potentially degrade or even destroy products that are sensitive to moisture. The 3 most
commonly used desiccants include:
1. Silica Gel Desiccants
Silica gel is a granular form of silica that is made synthetically from sodium silicate. It is
non-hazardous and can absorb upwards of 40% of its weight in water vapor at 100%
humidity. It is a solid substance that is extremely porous, making it capable of absorbing
high levels of moisture, it has the highest moisture adsorption capacity of any commercial
desiccant making it one of the most effective ingredients for products designed to
prevent corrosion during transportation and storage.
In cases where moisture needs to be eliminated entirely, the use of powerful desiccants
such as silica gel may not be enough. To that end, moisture barrier bags can provide the
level of protection required. When used in conjunction with silica gel, the levels of
moisture can be reduced to infinitesimal levels. The use of indicating silica gel can also
be a great help, it is a simple yet effective way to ensure that moisture levels remain at a
minimum. Not only does indicating silica gel absorb surrounding moisture, it also
changes colors as it does so. The more moisture the silica gel absorbs, the less effective it
eventually becomes. Once it reaches its saturation point, indicating silica gel will turn to a
specific color, signaling it should be replaced.
2. Molecular Sieve Desiccants
Molecular Sieve is the most aggressive of the primary desiccants and our first choice for
the most demanding and unique applications. A distinctive feature of this non-hazardous
synthetic product is our ability to control the uniformity of pore size openings during the
manufacturing process.
This yields selective adsorption characteristics that can be very useful drying packages
without removing other desirable molecules, such as volatile organics that might be
present in the package. Molecular sieve can hold moisture to temperatures well past
450°F (230°C) and, because of its high affinity for moisture, can bring the relative
humidity in packages down as low as 10%.
3. Montmorillonite Clay Desiccants
Montmorillonite Clay is the least expensive of all desiccants and is a naturally occurring
non-hazardous mineral composed of magnesium aluminum silicate (a calcium aluminum
silicate type of hydros clay).
Montmorillonite Clay is used in most industrial applications requiring humidity control
because it recharges easily and does not swell as it adsorbs water vapor. Subject to a
degree of variability for being a natural material, clay desiccant will adsorb
approximately 25% of its weight in water vapor at 77º F and 40% relative humidity.

2. This desiccant works well at low and room temperatures, but has a rather low ceiling
temperature. At 120º F montmorillonite clay will begin to desorb or shed the moisture it
has adsorbed, an important consideration for storage in hot areas.
Desiccants on their own can be extremely effective, although they work better when used
in combination with moisture barrier bags. Different moisture barrier bag materials come
with different MVTR ratings. These ratings are extremely important, as they are the only
reference point when it comes to the amount of moisture that can seep in over a period of
time. Currently, the most effective moisture barrier bag material has an MVTR rating of
0.02, meaning that only 0.02 grams of moisture can penetrate the material over a 24-hour
period in 95 percent humidity.
Proper protection from moisture is important. To that end, combining moisture barrier
bags with a desiccant is one of the most efficient ways to protect your goods. No matter
how effective a moisture barrier bag may be, there is always a possibility that a minute
amount of moisture may seep in. The use of desiccants is a smart preventive measure for
added protection.
About Protective Packaging
Protective Packaging specializes in protecting products, equipment, and machinery from
corrosion, electrostatic discharge, contaminants, ultraviolet rays and dust during shipping
and storage. Our corrosion prevention products and services consist of: anti-static and
static shielding bags, flexible packaging materials, moisture barrier bags, Mil-Spec
(military specified) packaging materials, corrosion inhibitors, desiccants, humidity
indicator devices, on-site packaging, packaging consulting, and custom-made packaging.
For more information, please visit http://www.protectivepackaging.net