Silica gel is a granular, vitreous, porous form of silica made synthetically from sodium silicate. Despite its name, silica gel is a solid. It is a naturally occurring mineral that is purified and processed into granular or beaded form. As a desiccant it has an average pore size of 2.4 nanometers and has a strong affinity for water molecules.
It’s high surface area (around 800 m²/g) allows it to absorb water readily, making it useful as a desiccant to control local humidity in order to avoid spoilage or degradation of some goods.
We supply many different types of silica gel
Standard white silica gel
Standard white silica gel is referred to as being non-indicating. As it absorbs moisture it remains physically unchanged. Non-indicating silica gel is both cheap and effective and available loose in bulk packs, packed in the tin, or packed in sachets.
Self-indicating silica gel
Self-indicating silica gels have a moisture-sensitive additive added to the basic silica gel. This indicator changes colour as moisture is absorbed thus giving a visual indication as to the activity level of the silica gel.
Advantages of silica gel as a desiccant
- It will absorb up to 40% of its own weight in water vapour. This absorption efficiency is approximately 35% greater than typical desiccant clays, making silica gel the preferred choice where weight or efficiency are important factors.
- It has an almost indefinite shelf life if stored in airtight conditions.
- It can be regenerated and reused if required. Gently heating silica gel will drive off the absorbed moisture and leave it ready for re-use.
- It is a very inert material, it will not normally attack or corrode other materials and with the exception of strong alkalis and hydrofluoric acid, is itself resistant to attack.
- It is non-flammable.
- It is most frequently and conveniently used packed in a breathable sachet or bag.
- These are available in granule, creaked bead or round bead form in a wide range of sizes.