Moisture. It is the main nemesis of metal, wood, and important documents. Especially in a confined place, like a gun safe.

Fortunately, there is an easy (and cheap) way to vanquish it!

In this instructable, I'll show you how to make a gun safe dehumidifier. It's not just for gun safes though, you can make these to any size you need, and use them any where you need to remove moisture: jewelry box, silver drawer, file cabinets, document safe, ammo boxes, you name it.

You can buy plug-in rechargeable dehumidifiers pretty cheap nowadays (this one is only $15). We are basically going to recreate this type at a much cheaper scale.

There are many ways you can tweak this instructable to serve your purposes. I'm going to show you the method I developed after a number of trial versions. This method is cheap, and easy to recharge.

Step 1: Understanding Moisture

Let's start off with getting a better understanding of the problem.

We all know that moisture will cause metal to rust, wood to warp, and documents to mold.

HOWEVER, a complete removal of moisture isn't always the solution. Documents and metals would probably benefit from 0% humidity, but wood needs to have some moisture in it.

The wood stock of your firearm will benefit from keeping your gun safe at about 50% humidity. If you removed all moisture from your safe (and hence the stock), then went out in the woods on a rainy hunt, the stock will start sucking moisture in and potentially swell and warp. As with most things in life, avoid extremes.

Keeping your safe at a stable temperature will help manage humidity problems. First, you need to understand if you have a problem. Hygrometers (humidity sensors) are cheap. And you can get cheap "weather stations" that have temperature and humidity monitors for under $20 (like this one), that will keep track of the highs and lows as well as show the current readings.

If your safe is at 50% humidity and a stable temp (60-70), you are probably in good shape.

If your safe is in your garage, or somewhere with major temperature swings, you should deal with that first. A plug in safe dehumidifier that works by heating (like this one) will give you better results, since it will even out your temperature swings.

But if your safe is in your basement, and just has high humidity, read on!

Step 2: Gather Your Supplies

You will need:

Cheese Cloth - [Click to see example]
Coffee Filter - any kind will do
1/2 pint canning jar with ring - head to Wally world if you don't have any on hand. You can actually make these whatever size you want. I like to use some of the "fancy" jars, and make these as Christmas presents.
Silica Gel Desicant - You can get these for free, they are the little balls that look like tapioca pudding in the packets they stick in shipping boxes, clothes (pockets sometimes), shoe boxes, etc. Save these up over time, get your friends to save theirs for you, you'd be amazed at how quickly they add up.

An alternative to saving the desiccant packets is to use silica kitty litter. It HAS to be the silica type, which looks like white crystals, sometimes with blue crystals added.

I like to add some blue indicator crystals like these. These are optional, but the benefit is you will KNOW when it's time to recharge your dehumidifier because they will change from blue to pink.

These blue silica gels are pretty cheap too - if you wanted to just use them, you can get 2 lbs for under $20. That will give you enough to make quite a few dehumidifiers if you wanted.

Step 3: Put It Together

The cheesecloth can be omitted here, but it makes recharging it MUCH easier and faster, because it increases the surface area of the crystals exposes when heating it.

Cut a square of cheese cloth big enough to line your jar. You want to leave a little excess that we can gather together to wrap it together.

Add the silica gel of your choice. If you are adding blue ones to the white, add enough and mix them thoroughly so that you can see a good number of them through the jar and the cheesecloth - they won't help us if we can't see them change color!

NOTE: Silica gel on it's own is non-toxic. The blue additive (if you use the blue crystals) however does have some toxicity to it. I use a spoon to add and mix them, so I never actually come in contact with them.

Once your jar is packed, gather the loose ends of the cheesecloth together, and seal it tightly with a zip tie or twist tie.

Cut off the excess cheese cloth.

Step 4: Cap Your Jar

If you made the cheesecloth bag, you can just use that as it is. Putting it in the jar just pretties it up a bit.

Adding the coffee filter cap is also optional if you used the cheesecloth in the prior step. If you use loose beads though, it's required. You don't want to accidentally spill those silica gel beads!

Put your coffee filter over the jar, and tighten the ring down over it.

Use scissors to cut the extra filter from the edge of the ring.

You have finished your safe dehumidifier!

Step 5: Recharge Your Dehumidifier

If you recycled your silica gel from packets, I like to recharge them BEFORE I make the dehumidifier, that way it's ready to go in the safe as soon as it's assembled. Simply bake the packets in the oven at 250 degrees for a few hours (2 to 3).

DO NOT place the original packets directly on the oven rack. The seams are usually glued, and this will separate during the heating, and beads will go everywhere. Place them on a cookie sheet to bake them.

To recharge your completed dehumidifier, you basically follow the same process. If you used the cheesecloth liner, when the crystals turn pink, pull it out of the jar, put it on a cookie sheet, and bake at 250 for 2-3 hours. When the crystals turn blue again, it's recharged!

If you didn't use the blue crystals, you'll have to guess when it needs charging. But 2-3 hours should do it for the recharging process.

If you didn't use the cheesecloth liner, you can spread the beads out on a cookie sheet to do the same thing. It's not as much fun pouring the beads back in the jar though.