Molecular Sieve vs Silica Gel: What’s the Difference?

The quality and shelf life of a product is paramount, especially in the healthcare industry. Medications that line store shelves or are dispensed by a pharmacy can’t degrade or become less effective as they wait to be consumed.

To protect pharmaceuticals, supplements, vitamins, and diagnostic products like pregnancy tests, many companies add a desiccant to control moisture and maintain the product’s effectiveness over time.

There are many kinds of desiccants to choose from, but the two most commonly used in the healthcare industry are: Molecular sieve and silica gel.

Understanding the difference

Both molecular sieve and silica gel are moisture-removing desiccants that help keep products from degrading. However, the two desiccants are quite different.

Silica gel

Silica gel is a form of silica that’s processed into various forms like granules or beads. Silica gel works like a sponge, drawing moisture into its many pores. It has the power to absorb up to 40% of its weight in water. Aside from its impressive moisture-removing abilities, this material is approved by the FDA for food and drug packaging.

Molecular sieve

Molecular sieve is aluminosilicate and absorbs water vapor from the air through its 3D structure. Molecular sieve is a fast-drying agent, with the ability to trap moisture quicker and more aggressively than silica gel. This material is ideal in products that require low humidity and remains stable when temperatures rise.


Rate of adsorption (moisture capture)  EXCELLENT GOOD
Functionality in high temperatures   EXCELLENT FAIR
Capacity at low Relative Humidity (RH)   EXCELLENT POOR

How to choose between molecular sieve and silica gel

While the information above explains how molecular sieve and silica gel differ, there are many factors to consider when selecting a desiccant for your product. Before making a decision, consider these additional factors:

  • Relative humidity
  • Temperature range
  • Moisture fluctuations
  • Pressure changes
  • Mechanical forces
  • Assembly options

Adding a desiccant to a product

Both molecular sieve and silica gel can be integrated into a product with ease. Desiccants can take on many shapes, from a packet or canister to an adhesive or many other formats, there are solutions for every application.

Still need a little help deciding between molecular sieve and silica gel? Contact Multisorb for desiccant advice.

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