Prosorb 500g Sachet

Description

PROSORB is a silica gel ideally suited for stabilizing relative humidity (RH) inside museum display cases and storage cabinets. Thanks to its large inner surface area and its ability to adsorb and desorb water vapour, PROSORB can maintain a stable RH within narrow margins. It is supplied pre-conditioned for the individual humidity level you require. PROSORB offers unique and exceptional adsorption capacity within the 30 – 60% RH range, and surpasses other products sold for this purpose. Most museums tend to maintain their collections at an RH of between 30 – 60%. Thus PROSORB precisely matches the needs of museum conservators.

What pre-conditioning will I need?

The optimum pre-conditioning value largely depends on the requirements of the exhibit. Buffering humidity always implies buffering to an RH range, not to a simple RH point. Depending on whether ambient climatic conditions are drier or more humid than the desired humidity range, pre-conditioning of PROSORB will have to be at the upper or at the lower end of the desired RH range.

Example: You want to keep a display case at an RH of 45 – 55% and the ambient RH is 60%. Ambient air will gradually enter even the best-fitted display case. The PROSORB should be pre-conditioned to 45% RH in order to adsorb as much moisture as possible.

If ambient RH is similar to the desired RH range of the showcase and the aim is simply to buffer RH fluctuations, pre-conditioning in the middle of the desired RH range should be chosen.

How much PROSORB do I need?

The amount of PROSORB that you need depends on a variety of factors. These include the tightness of the display case and the ambient climate. It is therefore difficult to make predictions. Basically, the more PROSORB is used, the smaller the humidity fluctuations will be and the less frequently the display case will require maintenance. We recommend beginning with 2 – 4 kg of PROSORB per cubic metre of display case volume and constantly monitoring RH in each display case with a hygrometer.

Guideline values are:

• 2 kg/m³ for glass hood or large display cases > 2 m³
• 4 kg/m³ for very tall or small display cases (< 0.2 m³)

The required amount increases with:

• leakages in the display case
• high moisture gradients between the display case and the ambient air
• long exhibition durations or permanent exhibitions
• temperature fluctuations and air movements
• hygroscopic display case installations that are drier or damper than the desired climatic range. The exhibits themselves may sometimes be drier or damper than stated by the lender.