How To Recharge Silica Gel Crystals
Silica Gel absorbs moisture in the air around your camera equipment (such a material is called an adsorbent). This ensures that the area is not friendly for fungus to grow inside your camera lenses (article I wrote about keeping fungus at bay). But did you know that if you leave silica gel inside your camera bag for too long it can get saturated with moisture and actually start to give off some of that moisture later on? This could really mess up your equipment. I didn’t know this myself, until a few years ago.
Here’s how you can avoid this potentially huge problem, and recharge Silica Gel sachets or crystals that you use to keep your camera equipment safe from moisture.
What Type of Silica Gel Should I Buy?
Silica Gel comes in a few different forms. Typically they’re sold loose, as crystals, tiny spheres, or in porous plastic sachets that allow air through. I prefer to get the loose spheres or crystals because it’s not easy to see when the crystals are saturated when in sachets. More specifically, I prefer to buy indicative Silica Gel. This is also called reactive Silica Gel.
The sachets are very convenient for some non-photographic uses.
How Do I know When My Silica Gel is Saturated with Moisture?
Normal Silica Gel is white, so it’s difficult to know when it is saturated with moisture. This is why I prefer to use Indicative Silica Gel. These Silica Gel crystals are blue when fully active, and become pink when they are saturated with moisture. There is also a variety that is orange when fully active, and that turn green when saturated. The orange type is preferred, as the chemical used to show moisture content may be less toxic.
Quick TIP: You can keep track of how humid any space is, by using a Digital Hygrometer.
How Can I Restore or Recharge Silica Gel that is Saturated?
Silica Gel gets saturated with moisture rather quickly when there is a high level of humidity in the air, so it’s important to check on the crystals / sachets often during this time. Fully Saturated Silica Gel crystals can begin to give off humidity to the surrounding air when the humidity falls. This means that you need to refresh / recharge the crystals before they reach this point so that they continue to absorb water from the air.
The good news is that you can reuse these crystals as many times as you like, and the procedure is quite simple. All you need is an oven, an oven-safe dish, maybe some aluminium foil to hold the crystals, and you’re ready to recharge Silica Gel. Here are the steps:
- Spread the crystals across the bottom of a bake-safe oven dish (you can use aluminium foil if you prefer to keep it off the dish itself). Spread them evenly and less than an inch deep in the dish.
- Place the dish in an oven and heat it to 120° C (250° F) for 1–2 hours until they start changing colour. If you want to avoid the risk of making your Silica Gel inactive, you could use a lower temperature and leave the Silica Gel in for a longer period of time.
- CAUTION: Do not heat Silica Gel to more than 180° C because it will lose its ability to absorb moisture.
- The Silica Gel crystals will release the trapped water from within them, and revert to their original blue or orange colour. Once the colour changes fully, the Silica Gel is recharged and restored to its original capacity.
- Note that the chemical that actually indicates the there is water in the silica gel crystals is a little more sensitive, and will most likely turn blue before the Silica Gel is fully refreshed. This is why we suggest leaving the crystals in the oven for a while longer, after the crystals turn blue / orange.
- Allow the crystals to cool down before you touch them, and then restore them to their perforated containers in your camera bag or cabinet.
- Store them in an airtight container so that they don’t absorb moisture from the atmosphere when they are not in use.
- Use an airtight storage container for your camera equipment so that humidity doesn’t come in from outside and saturate the Silica Gel crystals. Remember to recharge your crystals often enough, and you should be fine.
Some people say that you can use a microwave oven to recharge Silica Gel, however we recommend against it because there is no way to control the temperature of the crystals, and you risk making them inactive.
Is Silica Gel Toxic?
No, Silica Gel is not toxic, but you should not try to ingest it, or mix it with edible items. Also keep it away from children, eyes, etc.
In short, treat it with enough respect and you will be safe. Follow the link above for more information about precautions around children.
The Cobalt Chloride used in blue>pink indicative Silica Gel has been classified as hazardous if inhaled or ingested, so if you’re using indicative Silica Gel, don’t inhale the dust from the crystals. The Orange > Green Silica Gel is considered safe for use.
Where Can I get Indicating Silica Gel?
- Here’s an Amazon.com page with various options.
- Dry-Packs 45gm Indicating Silica Gel Hard Plastic Canister (Orange > Green).
- 1 Gallon Blue Replacement Desiccant Indicating Silica Gel Beads.
Thanks for reading right through to the end. Follow this link if you want more information about how to take care of your cameras when it’s raining, or if you live in a humid area.