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.
Homemade Silica Gel Packets
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.
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. Seal the gel in a porous material. If you have access to a sewing machine, sew a handful of silica beads into a folded coffee filter. If not, put the silica gel on a square of cheesecloth, silk or nylon stocking and tie it into a bag or secure it with a rubber band. 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.
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.
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. Used packets can be dried for reuse on a cookie sheet in a 250 degree Fahrenheit oven for two hours.