Recommended quantity of silica gel for temporary exhibition cases in rooms with moderate to good climate control are as follows:
RD gel 9 kg/m� or 0.55 lb/ft�
Art-Sorb 4 kg/m� or 0.25 lb/ft�
Rhapid Gel 2 kg/m� or 0.125 lb/ft�
Recommended quantity of silica gel for maintenance-free exhibit cases are as follows:
RD gel 18 kg/m� or 1.1 lb/ft�
Art-Sorb 8 kg/m� or 0.5 lb/ft�
Rhapid Gel 4 kg/m� or 0.25 lb/ft�
These recommendations are based on average exhibition conditions using standard assumptions about leakage rates and RH conditions within and outside the exhibit case. These recommendations were determined with the following equation, described in detail in the Objects Specialty Group article entitled Demystifying Silica Gel [Steven Weintraub, OSG Postprints (Vol. 9), 2002. Washington, D.C.: American Institute for Conservation].
Q = (Ceq D)V(Nt)/( MH F)
Through the application of this equation, it is possible to adjust the amount of silica gel required for a specific application. For example, if a case is measured and is known to be extremely airtight, it is possible to use less silica gel.
Why do some publications recommend 20 kilograms of silica gel per