Silica gel packets are commonly found packed with electronics and shoes to guard against corrosion or other damage from high humidity. Silica gel packets have many uses around the home protecting electronics and food, but packets can be difficult and expensive to buy commercially. You can make your own silica gel packets from common materials cheaply and easily.
What Is Silica?
Silica is chemically similar to quartz, but is very porous—like a sponge. Because of this, silica gel can absorb 40 percent of its weight in water. Commercially prepared silica gel packets bear the warning "Do Not Eat," though silica gel is not toxic. However, silica dust can irritate skin, eyes and the respiratory tract, so wear gloves, eye protection and a respirator when working with it.
Where to Buy Silica Gel
Silica gel is sold in bulk in most grocery stores as "crystal" cat litter. There are two varieties: irregularly shaped shards of silica and small round beads. Either variety absorbs moisture, but the round beads are easier to work with. You can also find powdered silica sold for drying flowers in the craft section of department stores.
Make Your Silica Gel Packet
To DIY your own packet, all you need silica gel and a porous material. Most fabrics will be ineffectual for this purpose. The best thing to use as your packet base is cheesecloth, silk or nylon stockings or a coffee filter.
Coffee Filter Packet
Gently fold a coffee filter in half a square, or a folded envelope and insert a handful of silica beads. Using a sewing machine or hand sewing, carefully sew the edges of the square together, taking care not to spill or tear the thin material. If a sewing machine isn't available, or you prefer another method, use a stapler to close the edges of the filter around the filter.
Cheesecloth and Nylon Packet
Cut your cheesecloth or nylon into a small square. The toe of a stocking is the perfect shape for this already. Lay the silica gel on a square of cheesecloth, and tie the corners of the square together or gather and secure all four corners of the square tightly with a rubber band to make a small bag. Silica gel will go directly into the toe section of the silk or nylon stocking. Gather the excess stretchy material above the gel and tie it into a tight knot, or use a rubber band. It will look like a small round bag.
Weigh for Moisture
Weigh and mark the weight on each packet so you'll be able to tell when the silica has absorbed the maximum amount of moisture. Store the packets in an airtight container if not used right away.
Unless the silica packet is in an airtight container, you will need to check to make sure it's still able to absorb water vapor. Weigh the packet. If the weight is over 30 percent of the original "dry" weight, the packet should be replaced. Don't toss out used packets! Used packets can be dried for reuse by placing them on a cookie sheet in a 250 degree Fahrenheit oven for two hours. After they dry for two hours, weigh and mark the weight as if they were brand new. Store in an airtight container with other packets.
Your homemade silica gel packets can be used anytime you need to reduce the humidity in a container. Throw a packet in with your camera and other electronics when putting them into long-term storage. Silica is nontoxic, so you can use your packets to keep stockpiled food dry. Gardeners use silica gel packets to keep stored seeds from growing mold and to keep tools from rusting in storage.