Did you know that silica gel needs to be recharged periodically to stay effective? As photographers we use silica gel in our camera bags and lens storage all the time. But silica gel needs to be recharged after it has been used for a while. As it absorbs water, it becomes saturated, and less effective. Not recharging silica gel regularly can lead to excess humidity in camera and lens storage, meaning that your lenses could be affected by Lens Fungus.
Table of Contents
Recharge Silica Gel:
Here are the basics that you need to know:
You can dry silica gel in an oven at 248 °F (120 °C) for 2-3 hours to recharge it. This method is tried and tested, and is safe for your Silica Gel.
Caution: Heating silica gel too much could inactivate the indicating dye, and heating it for too long would simply waste energy.
How to Recharge Silica Gel Using an Oven
The oven method is the most reliable way to recharge silica gel. It works for both indicating and non-indicating types, requires no special equipment, and restores the gel to near-original absorbing capacity.
- Prepare the dish. Spread the silica gel evenly across an oven-safe dish, no more than an inch deep. Line the dish with aluminium foil first if you’d rather not get gel residue on the dish itself.
- Heat at 248 °F (120 °C) for 2–3 hours. For indicating gel, it’s fully recharged once it has reverted to its original blue or orange colour. For non-indicating gel, weigh a sample before heating and again periodically – it’s done when the weight stops dropping.
- Don’t exceed 257 °F (125 °C) for indicating silica gel. Higher temperatures destroy the colour-changing indicator. The gel will still absorb moisture, but you’ll lose the visual cue that tells you when it’s saturated.
- Never exceed 392 °F (200 °C) for any silica gel. Above this temperature, the fine internal pore structure that traps moisture is permanently damaged and the gel loses its absorbing capacity.
- Cool inside the oven, then seal immediately. Hot silica gel will pull moisture from room air as it cools. Transfer it to an airtight container as soon as it’s safe to handle.
NOTE: We built easy to use calculators so you know: How much silica gel to use, and How long to recharge your silica gel.
How Long to Heat Silica Gel for Effective Drying
The table below is an approximate guide for drying fully saturated silica gel beads spread roughly 1 inch (2.5 cm) deep. Times shorten significantly if the layer is thinner or if the gel is only partially saturated.
| Temperature | Indicating Silica Gel | Non-Indicating Silica Gel | Notes |
|---|---|---|---|
| 212 °F (100 °C) | 4–6 hours | 4–6 hours | Slow but safest; good if unsure of gel type |
| 248 °F (120 °C) | 2–3 hours | 2–3 hours | Recommended sweet spot – efficient and safe for both types |
| 257 °F (125 °C) | 1.5–2.5 hours | 1.5–2.5 hours | Upper safe limit for indicating gel |
| 302 °F (150 °C) | ⚠️ Avoid – damages indicator | 1–2 hours | Non-indicating only |
| 347 °F (175 °C) | ⚠️ Avoid | 45–90 minutes | Non-indicating only |
| 392 °F (200 °C) | ⚠️ Avoid | 30–60 minutes | Absolute maximum – structure damage above this |
Factors That Change Drying Duration
- Layer depth: halving the depth roughly halves the time. Spread the beads thin for faster drying.
- Saturation level: partially used gel dries faster than fully saturated gel.
- Bead size: smaller beads (1-3 mm) dry faster than larger ones (5-8 mm).
- Oven type: convection (fan-forced) ovens are around 25-30% faster than conventional ovens.
- Airflow: stirring the gel every 30 minutes and running a fan in the oven speeds up drying considerably.
- Ambient humidity: drying takes longer on humid days than on dry ones.
Trust the Visual Cue, Not the Clock
For indicating silica gel, the colour change is the real signal. Pull the gel out when it has fully reverted to its original colour regardless of how long it has taken. For non-indicating gel, weigh a small sample before and during heating: when the weight stops dropping, the gel is fully dried. We don’t recommend non-indicating gel simply because it’s cheap and easy to use indicating gel.
Quick TIP: You can keep track of how humid your camera storage box is, by using a Digital Hygrometer. I highly recommend using one.
Does My Silica Gel Need To Dry More?
- When indicating silica gel changes color, it is full of moisture. You should recharge it (dry it out) at this point.
- Orange indicating silica gel desiccant turns green, and blue silica gel turns pink.
- Normal silica gel is white, so it is difficult to know when it has become saturated with moisture. However, when Indicating silica gel is saturated, its colour changes, so it is easy to know when to replace it. This is why I prefer to use Indicating silica gel.
- If you already have white silica gel, you could buy a little indicating silica gel, and mix indicating and non-indicating silica gel. The Indicating silica gel will help you to judge the condition of all your silica gel combined.
- Finally, keep a Hygrometer in your camera’s dry box. This tells me what the rh (relative humidity) is at all times. When it starts to rise above 50% RH, I recharge my silica gel beads
Quick Tip: Use sufficient silica gel, based on the interior volume of your container. Calculate the volume of your container, and then use 50 g/litre volume, or more, of silica gel. The more silica gel you use, the less frequently you will have to replace the silica gel in the container.
Reuse Silica Gel
When exposed to humid air for an extended period of time, silica gel adsorbs moisture. The microscopic pores in beads become saturated with water when exposed to humid air. If your camera case is not airtight, more moisture will continue to enter, until the air becomes uniformly humid. This will again pose a risk of lens fungus.
To avoid saturating your silica gel with moisture, you should keep your cameras and lenses in an airtight box when in long-term storage.
Drying out your silica gel beads on a regular basis allows you to keep your camera equipment safe from fungal growth, by keeping moisture at bay, and keeping the relative humidity low.
The good news is that you can easily dry out (or recharge) your silica gel beads, and use them repeatedly. This will keep your camera equipment safe from fungus growth and moisture damage.
How Many Times Can Silica Gel Be Reused?
Silica gel can be reused up to 500 times or more. This makes it an eco-friendly option. silica gel’s efficiency decreases after about 100 uses, but it still remains quite efficient at removing moisture from the air almost indefinitely. One should remember not to overheat it, or its internal structure will be destroyed.
Drying Silica Gel Using a Microwave – Don’t!
We do not recommend using a microwave to recharge silica gel.
Silica Gel adsorbs water vapor into microscopic pores in its structure. Microwave ovens can not regulate the temperature of the materials in them as well as convection ovens, resulting in spikes of high-temperature steam which shatters the porous structure of gilica gel. When we tried using a microwave oven, the translucent silica gel beads became white and cloudy.
For best results, we suggest using low heat in a conventional convection oven for a longer period of time, as mentioned earlier.
Storing Recharged Silica Gel For Long Periods
If silica gel is not stored properly it will immediately start to absorb moisture again. It should be kept in an airtight container until it’s ready to be used.
- Store silica gel in an airtight bag or container after it is dried out. You can use Tupperware, airtight storage boxes, or some vacuum-sealed airtight container.
- If there is an air leak in the container, it will reabsorb moisture from the air.
If left out in the open, silica gel beads will quickly absorb moisture from the air around it and lose its effectiveness.
Additional Information:
The Cobalt (II) Chloride used in blue>pink indicative silica gel has been classified as hazardous/carcinogenic if inhaled or ingested, so if you’re using indicative silica gel, don’t inhale the dust from the crystals.
The orange to green silica gel is considered safer for human use.
Plain white silica gel is the safest option as there are no added chemicals.
Where Can I Get Indicating Silica Gel?
- Here’s an Amazon.com page with a wide choice of Indicating Silica Gel options.
- Dry-Packs 45g indicating silica gel hard plastic canister (Orange > Green).
Personally, I use 2Kgs of orange beads of Silica Gel.
Precautions To Take When Using Silica Gel
Silica gel is safe to handle and use by itself. Skin contact is not a problem. Still, here are a few precautions that you can take when using, storing, recharging, and handling silica gel. See the safety data sheet linked below.
- Silica gel should not be handled by children. Avoid eye contact, inhalation or ingestion. If ingested, silica gel is not toxic and will pass through the digestive system. However, the beads and packets are considered a choking hazard for small children.
- Do not inhale any dust that comes off silica gel. It could cause irritation to the nose and lungs and may cause discomfort if it touches the eyes.
- When recharging silica gel in an oven, it may remain hot for quite a while. You can allow it to cool down in the oven until it is safe to handle, and then transfer it to an airtight sealed container for long-term storage.
- Orange silica gel – Comprehensive Safety Information.
NOTE: We built tools to calculate How Much Silica Gel to Use, and How Long to Recharge Silica Gel.
Reference Material
Now that you have read 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.
- Demystifying silica gel – Steven Weintraub, Objects Specialty Group Postprints, Volume Nine, 2002 (PDF)
- Comprehensive Information about Silica Gel (PDF)
- Silica Gel: Passive Control of Relative Humidity – Technical Bulletin 33 by Jean Tétreault and Paul Bégin
- What’s The Difference Between Orange & Blue Indicating Silica Gel?
- What to do if Silica Gel is ingested
- Silica Gel Technical Information Sheet (PDF)
- Cobalt Chloride Information Sheet
- What’s better than Silica Gel for Long-Term Camera Storage? A Dry Cabinet!
Hi Susheel, recently acquired a new dry cabinet wth digital indicator outside ,but has a manual setting inside the cabinet ,which is set for RH of say 43 %.Is such type of dry cabi.is any way less efficient than the one called ‘digital’,which has controls outside the cabinet?I wl have to ,anyway,open the cabi.to get my gear out ,right?So whats a big deal of having control outside?
Pls xplain d diff.I am confused..I already invested in a ‘manual’ Dehumidifier.Regards.Dr.Mhatre
Hello Dr. Mhatre,
Thanks for stopping by and leaving your comment. From what I understand, the efficiency of the dehumidifying mechanism would not vary much based on digital or manual controls and / or their placement. Usually, digital controls do offer more fine-grained control over the RH that is maintained, turning the mechanism off and on more frequently than analog controls. PS: these cabinets do not need to have their settings changed once set. They’re essentially set-and-forget. 40% seems like a good place to keep the RH. I don’t think you should ever need to change it. So based on that, you could decide to get the one with the controls inside the cabinet, or outside. Do let us know what you decide to do. Your insight could prove valuable to others. Thanks :D
good day for all,
i would like to ask about the optimum way to use silica gel blue(2-4 mm) as a dryer, what is the required quantity to the suitable area, humidity, ….
thanks
Hi Ahmed,
While there are some research papers that talk about how much silica gel to use per x volume of air for long term storage, these papers are directed towards use for museum showcases, and for the preservation of manuscripts and other fragile items. I’d suggest that you should decide the relative humidity level that you want to maintain, then get a hygrometer to check the actual humidity of the space. Experiment so that you’re able to maintain a humidity level that you’re comfortable at. I personally put about 100 grams of the orange balls into a perforated plastic container to get the humidity out of a 2x4ft box. I change the silica gel beads every week or two. I think that it has worked for me so far.
Hope that helps.
Susheel
i agree with this article. Working with Sorbead India in this industry have opened my eyes as to how vital are those silica gel packets.
Thank you! Do you have any further tips to add from your experiences?
I was just curious if anyone has ever tried using an air fryer to recharge desiccant?
Or if you think that may be a suitable methods?
Hi Adam, Not having used an air fryer I couldn’t really tell you for sure. A quick search shows me that Air Fryers typically operate at 200 Degrees Centigrade. This is too hot for Silica Gel, which needs about 100 Degrees Centigrade. If yours has a variable temperature that goes down to 100 Deg Celcius, you can definitely give it a try. Let us know what happens. :) Thank you for stopping by and commenting.
i am using white silica gel. but i am confused when to recharge it. does it turn in any color when it needs to recharge or is there any other way to get to know…?
Only Indicating Silica Gel changes colour when it is saturated. This is usually coloured orange/yellow or blue. If you have white, colourless Silica Gel, then there’s a chance that you will saturate it without knowing so. I’d suggest buying some Indicating Silica Gel as soon as you can.
I have one air tight dry box with analog humidity indicator. But I also buy 2 digital type too. I know that lowest and highest value is differs one to another. But when it indicate some stable condition in the middle of range. they also indicate quite differ value, For example, 2 different brand digital humidity indicator indicate 26%and 47%, while analog indicator indicates 65%, Silica gel already had turned to pinkish color. Which value should I believe. Which brand of humidity indicator more accurate?
That’s a great question and one that I should probably investigate in a different article. However, for the moment I think you should believe your Silica Gel.
If the Silica Gel is pink, it is already time to recharge it. Don’t leave it in your dry box. I would investigate whether you should use a bit more of Silica Gel – if it is getting saturated quickly.
I understand that your box is airtight, so it shouldn’t be getting saturated if you’re not opening it often. If you do open it often, remember to recharge the Silica Gel in a timely manner.
I didn’t know that heating them up in a micro could damage its functionality. I will have to switch to using the oven. Thanks for the information, my friend!