What is a Desiccator?

Desiccators are sealable enclosures containing desiccants used for preserving moisture-sensitive items. A common use for desiccators is to protect chemicals which are hygroscopic or which react with water from humidity.

The contents of desiccators are exposed to atmospheric moisture whenever the desiccators are opened. It also requires some time to achieve a low humidity. Hence they are not appropriate for storing chemicals which react quickly or violently with atmospheric moisture such as the alkali metals.

Desiccators are sometimes used to remove traces of water from an almost-dry sample.

A desiccator is also an economical and reliable way to assure dry, dust-free storage and organization of humidity sensitive products such as valuable
reagents or electronics. Proper storage conditions can be optimized by selecting a desiccator size,
shape and control mechanism best suited to your application, space requirements and items to be stored 

How do you choose the proper desiccator?
First decide what method of desiccation best suits your needs. Each method has its unique
advantages and trade-offs. Standard desiccators typically use desiccant cartridges and
are economical, but they require monitoring so that cartridges can be changed as needed
to maintain a continuous dry environment. Automated desiccators regenerate desiccant
as needed requiring minimal monitoring and no worries about samples being compromised,
but are generally more expensive than standard desiccators. Vacuum desiccators remove
air and moisture with the use of an in-house laboratory vacuum or vacuum pump and can
be brought back to vacuum easily after opening. Vacuum desiccators can also be used for
degassing techniques. How long vacuum is maintained can vary from model to model.
Gas ported desiccators are available for desiccation with gases such as argon and
nitrogen to achieve ultra-dry environments.

How do you know what style and size of desiccator to choose?
Identify the size of the items you need to store and in what quantity. Where the desiccator
will be housed, its interior volume, and shelving options should be considered. Both round
and cabinet style desiccators range in size from quite small to very large.
Round style desiccators typically have one shelf, and a domed top to provide extra vertical
space. Cabinet style desiccators tend to have easier accessibility, greater storage capacity
and may have stacking ability to save exterior space. They often have multiple shelves,
many of which are adjustable to suit your needs. Traditionally vacuum desiccators were
only available in round style as a square shape would be expected to implode under
vacuum. Lab Companion desiccators, however have overcome this concern and can
withstand the vacuum, so they provide the benefits of vacuum desiccation with the ability
to store more items with easier access and in less space.

Types of Desiccators

Standard Desiccator (Glass / Plastic)

  • Manual monitoring and operation. Moisture is absorbed from air in the unit by using a desiccant. Once the desiccant is ‘saturated’ it must be regenerated through heating, or replaced.
  • Flexibility to use any type of desiccant (silica gel beads, activated charcoal, etc.) based on economics and convenience.
  • Portable
  • Economical functionality. Most desiccants can be regenerated periodically


Automatic Desiccators

  • Electric fans and heaters continuously regenerate the desiccant to prevent saturation and to automatically maintain a low humidity environment.
  • Convenience, requires minimal monitoring.
  • Precise control of humidity. Operates on a set schedule of desiccation followed by a regeneration period.
  • Process uses silica gel beads that last for thousands of regeneration cycles.

Gas Purge Desiccators

  • A slow steady flow of inert gas (often dry nitrogen) is provided.
  • Achieve relative humidity at a much faster rate.
  • Dust free and desirable for many applications including clean room environments.
  • Option to close stopcocks and use with regular desiccants.

Vacuum Desiccators

  • Air and moisture are removed from the chamber by use of a vacuum pump.
  • Best for total dry storage or if air could be damaging to material being stored.
  • Dust free and desirable for many applications including clean room environments.
  • Option to close stopcocks and use with regular desiccants

Information required to to quote on a Desiccator

  1. Do you need a standard, vacuum type or auto-desiccator?
  2. Glass or acrylic?
  3. Do you require cylindrical or cubic shaped?
  4. What size do you require?
  5. Do you require UV protection or amber stained type?

Further Reading

How Does a Desiccator Work?