PROSORB This is a modern silica gel developed for stabilising relative humidity (rH) in museum display cases. The product is supplied pre-conditioned to a specific humidity level.

Thanks to its ability to both absorb and release water vapour, PROSORB maintains a constant relative humidity level inside the display case. In museum practice, it is standard practice to store organic objects within a range of 40–60% rF and to maintain this level at a constant value.

Within this humidity range, PROSORB performs exceptionally well – better than comparable materials. The choice of the appropriate variant depends on the target rF value and the type of packaging used. Within the 40–60% rF range, the product provides optimal conditions for works of art made from organic materials.

The main advantages of PROSORB:

• Chemical safety – The product does not contain chlorine (unlike many industrial equivalents). Unlike ART SORB, it also does not contain lithium chloride, which can cause metal corrosion or be transferred to objects through contact or dust. Composition: 97% SiO₂ and 3% Al₂O₃;
• low resistance – compared to other silica gels, PROSORB is significantly less dusty, which is of great importance when using loose beads;
• High density (compactness) – 1 kg of product takes up only approx. 1.5 litres in volume, which saves space while maintaining the same absorbency properties. PROSORB cassettes hold more material than ART SORB cassettes;
• stability over time – unlike many other gels, whose properties deteriorate after 1–2 years, PROSORB remains stable for a long period;
• favourable price – a more economical solution than other products with similar applications.

Unlike ART SORB, the conditioning level of PROSORB depends on temperature. The values given are for 20°C. When the temperature drops to 10°C, the relative humidity decreases by approx. 1.5% rF, whilst when it rises to 30°C, it increases by approx. 1.0–1.5% rF. In practice, when climate-controlling display cases containing wooden objects using PROSORB cassettes, temperature changes do not cause any exchange of moisture between the material and the objects.

The product can be ordered conditioned to 40%, 45%, 50%, 55% or 60% rF. The parameters given refer to a temperature of 20°C (±2% rF).