2  Silica Gel Basics/Buffering Capacity

Measuring the Effectiveness of Silica Gel: Moisture Buffering Capacity and MH Value

Preconditioned silica gel is used to slow down the rate of change in relative humidity within a sealed exhibit case or storage unit. The property that determines the relative effectiveness of Arten Gel, Rhapid Gel and other types of silica gel used for stabilizing relative humidity is the gel’s MH value, representing the gel’s moisture buffering capacity within the designated RH range of use.

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A HIGHER MH VALUE INDICATES A HIGHER BUFFERING CAPACITY. THEREFORE, LESS SILICA GEL IS NEEDED TO ACHIEVE THE SAME BUFFERING EFFECT AS A SILICA GEL WITH A LOWER MH VALUE

Comparing the Performance of Museum-Grade Silica Gels

The Moisture Buffering Capacity bar graph below illustrates the relative effectiveness of different types of museum-grade silica gels. 

  • Since Arten Gel is an A-Type gel, it has the same performance characteristics as other standard  A-Type silica gels.

  • Rhapid Gel and PROSorb have comparable performance characteristics since they have similar chemical and physical compositions. 

  • The relative effectiveness of other types of silica gel can be determined by comparing their MH values within the appropriate RH range of use.

Comparing the Performance of Arten Gel and Rhapid Gel

Within the Range of 20% - 30% RH

  • Rhapid Gel (MH=4.4) would require 1.25 times as much gel as Arten Gel (MH=5.5) for comparable performance. Since the difference in MH values between the two gels is relatively small, either type of gel would work well within the range of 0-45% RH. 

  • The primary benefit of Arten Gel is the relative cost of an A-Type gel compared to a high-performance silica gel such as Rhapid Gel for use in a low RH range.

Within the Range of 40% - 60% RH

  • Arten Gel (MH=1.9) would require 2.8 times as much gel as Rhapid Gel (MH=5.4) for comparable performance. 

  • Therefore, Arten Gel is not recommended for applications where the RH range will exceed 45-50% RH for an extended length of time.