2. Preventing Tool Rust with Silica Gel Packets

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Sometimes when you buy a toy, electronic device, or gourmet food product, you'll find a white packet labeled “Silica Gel - Do not eat - Throw away”.

Silica gel pack containing silica gel beads

Silica gel pack containing silica gel beads.

Instead of throwing away the silica gel packets, toss them into your tool drawers. Or, to be more effective, put the silica gel packs in plastic containers with your tools so there isn’t a constant supply of humid air from the environment.

Silica gel is a desiccant -- the silica beads absorb moisture. The term “gel” is a misnomer; the beads are hard and brittle.

A variety of plain and indicating silica gel beads

A variety of plain and indicating silica gel beads.

Ordinary non-indicating silica gel is clear. It consists almost entirely of silicon dioxide, with some varieties including aluminum oxide (or alumina -- the same material as sandpaper).

Indicating silica gel turns different colors depending on whether it is dry or moist. For example, blue silica gel turns clear and then pink as it absorbs moisture. I’ve also seen orange silica gel that turns clear, and green silica gel that turns brown. Other colors, such as brown silica gel (doesn’t change color) differentiates it as a special formulation of a premium drying agent.

Safety - Silica Gel Poisoning

Believe it or not, the US government and manufacturers say that clean, pure, non-indicating silica gel is non-toxic / not hazardous to touch or consume (Generally Recognized As Safe (GRAS) by the FDA). The reason it says “Do not eat” on silica gel bags is that it is not food. This is not a delicious candy treat included as a thank you gift for buying their product.

However, silica gel beads may come in contact with cutting oils, pesticides, and other containments. Also, indicating (colored) silica gel may contain additives such as cobalt (II) chloride, which may cause cancer. And, depending on its intended purpose (like drying flowers) some silica gel may include a fungicide.

For these reasons, don’t eat silica gel and do keep silca gel away from children, pets, and drunken frat parties. If a person or animal consumes a packet of silica gel, they’re probably going to be just fine, but you should seek advice from a medical provider to be safe.

Silica gel dust can be an irritant, so use a filter mask when working with them, and try to avoid grinding the beads or using a silica gel powder.

Buy Silica Gel

Over time, you can accumulate a small collection of free silica gel packets. But, if you need more, you can purchase bulk silica gel packets from eBay auctions or from McMaster-Carr (such as part number 2189K16).

McMaster-Carr also sells aluminum desiccant canisters filled with blue-to-pink indicating silica gel beads (part number 2219K91 -- Mulitsorb Technologies Inc). If you put a bunch of non-indicating packets in the same container or drawer as an indicating silica gel container, you can use the color of the indicating beads to determine when they all need to be recharged.

Avoid mixing blue indicating silica gel beads together with non-indicating beads, as the blue ones contain a potentially hazardous substance and you’ve then contaminated the entire lot.

Silica gel beads in various containers such as a commercial aluminum perforated box, tea balls, and plastic containers with holes drilled in them.

Silica gel beads in various containers such as a commercial aluminum perforated box, tea balls, and plastic containers with holes drilled in them.

You can also buy silica gel by the pound and put it in your own containers. Stainless steel tea balls work well. Drilling holes in recycled plastic containers is the cheapest way to go, but I’m not sure the air circulation is effective.

Submerging a stainless steel tea ball into a container of silica gel beads to completely fill the inside of the tea ball.

Submerging a stainless steel tea ball into a container of silica gel beads to completely fill the inside of the tea ball.

If you had a permissive mother, then you'll remember this trick from your childhood of filling containers in the bathtub. To completely fill a tea ball with silica gel, simply submerge the two halves into a container full of silica gel beads and close the two halves together while submerged. Alternatively, you may want to only partially fill the ball, to leave room for the silica gel beads to shift around as the ball rolls -- to evenly expose all of the beads to the outer surface.

By the way, the standard silica gel spherical beads are shaped to allow air to pass through them, but the spheres can result in a huge mess (and potential slip hazard) if you spill them. So, some museums and industries prefer the silica gel amorphous granules in irregular shapes because they don’t roll away when spilled.

Reusing Silica Gel

Ordinary non-indicating silica gel is quite friendly from an environmental standpoint:

Silica gel that has come in contact with hazardous fumes or fluids should be disposed of in a responsible way similar to the substance that contaminated the beads. However, clean silica gel can (and should be) reused by drying it out.

Theoretically, you could use the Sun to dry out the beads by spreading them out on a dark surface in direct sun on a dry day. However, most people will chose to use a conventional oven.

Line a clean deep dish or non-coated metal pan with aluminum foil. Toss in the unopened silica gel packets, metal tea balls, or metal perforated containers. Loose silica gel or beads stored in plastic containers should be poured out onto the aluminum foil and spread out. Do not put plastic containers or plastic perforated bags into the oven!

If the pan doesn’t contain any paper / Tyvek packs, then it can be heated up to 300 degrees Fahrenheit for three hours. However, if you use packs, then keep it as low as 220 degrees Fahrenheit for five hours. Overheating can destroy the paper material, melt the Tyvek, and degrade the silica gel beads.

If some of the beads are indicating silica gel (like blue-to-pink), don’t be fooled by them quickly turning blue again. This doesn’t mean the moisture has been driven out. Let the beads bake for the full time period, otherwise they’ll change back again to their moist color shortly after being removed from the oven.

Of course, if you purchased the silica gel packets from a known source or manufacturer, use their directions instead of mine.

In the end, I prefer keeping silica gel in their original packets because I can toss them in drawers, boxes, and containers without the likelihood of spillage. And, I can toss them in a pan for drying. No mess, no fuss, no added expense.