About Silica Gel

About Silica Gel

Silica gel serves a dual purpose: it can either remove moisture from the air or act as a humidity-buffering agent to maintain a constant relative humidity (RH). Regardless of its use, it might require conditioning before the initial use or reuse.

There are two types of silica gel: indicating and non-indicating. Both can be dried in a regular oven, not a microwave, at 250°F (120°C). To ensure thorough drying, spreading the gel in a single layer on a baking sheet for about an hour is generally sufficient. If the silica gel is in containers that aren't oven-safe, remove it for drying unless the packaging specifies otherwise. Remember to replace it in the container after drying.

To condition silica gel to a higher RH, place it in a sealed container or zip-lock bag with a water source, such as a dish of water or a soaked sponge (ensuring no direct contact with the water). Allow it to equilibrate for a day. To test the RH of conditioned silica gel, enclose a sample in a sealed container or plastic bag with a hygrometer for one day and then take a reading.

For Further Reading:

Simplified Procedures for Reconditioning Silica Gel. © Steven Weintraub. American Institute for Conservation of Historic and Artistic Works.

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