All silica gels are hydroscopic, and respond to the relative humidity (RH) of the surrounding air in the
same way as most organic materials such as paper, textiles and wood. Like organic materials, the
amount of moisture in silica gel will increase as the RH rises, and will decrease when the RH falls.
Unlike organic materials that expand and contract with changes in moisture content, silica gel
remains stable. Also, unlike organic materials, silica gel adsorbs and desorbs much larger amounts of
moisture when the RH changes under normal conditions.
All exhibition cases have some degree of leakage. If the RH in the air surrounding the case is not the
same as the RH in the case, moisture will be transferred between the case and the surrounding air.
As the RH in the case increases or decreases, the moisture within the hygroscopic materials of the
case will gain or lose moisture in order to remain in equilibrium with the RH of the surrounding air.
Since the objective is to prevent a change in the moisture content of museum objects, we add silica
gel as a supplement to the case. Since silica gel, if used properly, gains or loses a much greater
quantity of moisture than the organic materials on exhibition, the presence of silica gel slows down
the rate at which the hygroscopic museum objects gain or lose moisture. This is referred to as the
silica gel's buffering capacity.
All silica gels are hydroscopic, and respond to the relative humidity (RH) of the surrounding air in thesame way as most organic materials such as paper, textiles and wood. Like organic materials, theamount of moisture in silica gel will increase as the RH rises, and will decrease when the RH falls.Unlike organic materials that expand and contract with changes in moisture content, silica gelremains stable. Also, unlike organic materials, silica gel adsorbs and desorbs much larger amounts ofmoisture when the RH changes under normal conditions.All exhibition cases have some degree of leakage. If the RH in the air surrounding the case is not thesame as the RH in the case, moisture will be transferred between the case and the surrounding air.As the RH in the case increases or decreases, the moisture within the hygroscopic materials of thecase will gain or lose moisture in order to remain in equilibrium with the RH of the surrounding air.Since the objective is to prevent a change in the moisture content of museum objects, we add silicagel as a supplement to the case. Since silica gel, if used properly, gains or loses a much greaterquantity of moisture than the organic materials on exhibition, the presence of silica gel slows downthe rate at which the hygroscopic museum objects gain or lose moisture. This is referred to as thesilica gel's buffering capacity.
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