Silica gel, a granule form desiccant made from sodium silicate, absorbs moisture from the air to reduce the relative humidity to about 40 percent. Manufacturers of edible and non-edible products often include silica gel packets in their packaging to retard corrosion, mold and mildew. Free-flowing silica gel granules in canisters work in dehydrators for homes, hospitals and industry. You can dry silica gel packets or free-flowing silica gel in a standard oven, while you can dry free-flowing, color-changing silica gel in a microwave oven.
Spread free-flowing silica gel evenly in a shallow Pyrex dish. Place silica gel packets in the dish so they do not touch each other.
Place the dish in an oven. You can dry color-changing silica gel in a 900-watt microwave oven. The gel is blue when it is dry and pink when it is saturated. You only need dry it if it is pink.
Heat free-flowing silica gel at 300-degrees Fahrenheit for one-and-a-half hours per liter (about a quart dry measure or 30 ounces by weight). Heat packets at exactly 245-degrees Fahrenheit for 24 hours. Use an oven thermometer to ensure the temperature does not go over 300-degrees for the free-flowing, or over 245-degrees for the packets. For the color-changing silica gel, heat it at 900 watts in three-minute bursts in the microwave until it turns blue.
- Do not go over 300-degrees in the standard oven or 900-watts in a microwave. You will damage the silica gel and it will lose its absorbency.
- Heating the packets over 245-degrees will damage the packaging.