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How To Dry Silica Gel

How to Recharge Silica Gel

Silica Gel is a plastic-like substance that is typically seen in white sachets like the one shown below. Silica Gel absorbs moisture from the air and can help to prevent fungus growth on camera lenses. After a while, it becomes saturated with moisture and loses its ability to remove humidity from the air.

Thankfully, you don’t have to throw away your Silica Gel sachets. You can avoid sending them to the landfill by reusing your Silica Gel sachets. The process is really easy and I have reused my indicating Silica Gel beads at least a few hundred times over the last decade, and they still work just fine. Let me help you learn everything that you need to know about Silica Gel, and how you can use your Silica Gel packets for as long as you need to!

Yes, Silica Gel can be easily reactivated and reused many times by drying it in an oven at 120°C (248°F) for 1-2 hours; it can then be reused many times. Continue reading to learn more about this wonderful chemical and what you can do with it and its close cousin, “Indicating Silica Gel.”

Why Does Silica Gel Need To Be Dried?

When exposed to humid air for an extended period of time, Silica Gel adsorbs moisture from the air, and its microscopic pores become saturated with moisture. If your camera storage case is not airtight, moisture will continue to enter until the silica gel becomes saturated.

Once saturated, the beads will release some of the moisture back into the air, negating the previous benefits. This is why you should keep your cameras and lenses in a sealed box and why you should dry and recharge your Silica Gel on a regular basis, so that you can keep reusing it.

The good news is that you can easily dry out (or recharge) your Silica Gel beads and use them repeatedly, to keep your camera equipment safe from fungus growth and moisture damage.

How To Tell If Silica Gel Is Saturated With Moisture:

  1. When Indicating Silica Gel changes color, it is telling you that it is full of moisture. You should recharge it (dry it out) at this point.
  2. Orange Indicating Silica Gel turns green, and Blue Silica Gel turns pink.
  3. Because normal Silica Gel is white, it is difficult to tell when it has become saturated with moisture. On the other hand, it is easy to tell when Indicating Silica Gel is saturated. This is why I prefer to use Indicating Silica Gel.
  4. If you already have white Silica Gel, you could buy some 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.

How Much Moisture Can Silica Gel Remove from the Air?

Silica Gel can adsorb up to 37% of its weight in moisture. This means that each kg of Silica Gel can adsorb up to 370ml of moisture from the air around it.

Color-indicating Silica Gel changes color when saturated and has gained 8-10% of its weight in moisture. Even if the color changes at 8% of its weight, Silica Gel will continue to adsorb moisture up to 37% of its weight.

Is Silica Gel Efficient at Removing Moisture?

At room temperature and high humidity, Silica Gel is remarkably efficient at removing moisture from the surrounding air. It is more efficient at higher humidity levels.

  • Silica Gel will reach maximum saturation in about 5 hours at 25°C and 77% RH.
  • As long as the Silica Gel is not saturated, it can reduce RH (Relative Humidity) to less than 40%.

This would indicate that you would benefit from using more Silica Gel, rather than less. I use about 4.5 lbs for a box that is about 6 cubic feet in size.

Quick TIP: You can keep track of how humid your camera storage box is, by using a Digital Hygrometer. I highly recommend using one.

How Can I Dry/Recharge Silica Gel that is Saturated?

Indicating Silica Gel reused after restoring it to its original condition, by heating it in an oven at 120°C (248°F) for 1–2 hours to dry out the moisture that it has adsorbed. Once it is fully dried out, Indicating Silica Gel will return to its original color; either orange or blue depending on its type. At this point, its ability to adsorb moisture is fully restored, and it is ready to be reused.

White Silica Gel can safely be heated up to 150-175°C (302-347°F) to recharge it. White Silica Gel does not change color and remains white all the time.

How Many Times Can Silica Gel be Dried And Reused?

Silica Gel can be reused many times even though it can get saturated very quickly. From an environmental perspective, it’s nice to note that Silica Gel can be reused many hundreds of times. In fact, Silica Gel’s desiccating effect lasts quite well through many dozen cycles of adsorbing and drying, and is effective even after recharging up to 500 times (PDF). Though Silica Gel’s efficiency decreases after about 100 uses, it still remains quite efficient at removing moisture from the atmosphere almost indefinitely, as long as it is not overheated, and its internal structure is not destroyed.

Just remember not to heat the beads above 150°C or you may damage the indicating chemical element, or over 200°C or you will destroy the silica gel’s internal structures.

7 Steps to Dry Out & Reuse Silica Gel Repeatedly:

  1. Spread the Silica Gel across the bottom of a bake-safe oven dish (you can use aluminum foil if you prefer to keep it off the dish itself). Spread the beads or crystals evenly and less than an inch deep in the dish.
  2. Place the dish in an oven and heat it to 120° C (248° F) for 1–2 hours until it starts changing color. 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. When the Silica Gel has returned to its original color, it is ready to be taken out.
  3. Do not heat Indicating Silica Gel to more than 125-150° C because it will lose its indicating ability.
  4. Do not heat any Silica Gel to more than 200° C as its fine internal structures will be destroyed.
  5. The Silica Gel beads release the trapped water from within them and will revert to their original blue or orange color. Once the color changes fully, the Silica Gel is recharged and restored to its original capacity.
  6. To speed up the drying process, you can spread the gel out as much as possible, use a fan to circulate air, and periodically move around the Silica Gel layers to dry it out evenly.
  7. Finally, allow the Silica Gel to cool inside the oven, and quickly return it to a sealed airtight container, ready for later use.

Some Points to Note About Silica Gel:

  • The chemical that actually indicates the presence of water is a little more sensitive, and will most likely turn blue before the Silica Gel is fully refreshed, so keep it in the oven a little longer after the color changes..
  • Remember to use an airtight storage container for long-term storage of your Silica Gel and your camera equipment so that humidity doesn’t keep coming in and saturating the Silica Gel crystals.
  • Remember to recharge your Silica Gel often enough, and your camera equipment should last a very long time.
  • Silica Gel is safe, and you will not die from ingesting the white beads, despite what it says on the packets.

How Much Silica Gel Is Needed For A Space?

Absolute Humidity Calculation at 40% RH and 25 °C
Absolute Humidity Calculation at 40% RH and 25 °C

Silica Gel quickly absorbs moisture and can hold up to 40% of its weight in water. To keep the level of relative humidity consistently low, it is advisable to use more Silica Gel than may be required. Silica Gel reduces the humidity of the air to around 40% RH (Relative Humidity), but does not go much below that level. To calculate how much water must be removed from the atmosphere, we must first know how much is present, then we can calculate how much Silica Gel would be required to remove it. We can do this easily with a Relative Humidity (RH) to Absolute Humidity calculator.

With such a calculator, we can easily calculate how much water is in the air when the Relative Humidity and air temperature are known (easily done with a hygrometer). Then, we can calculate the difference between the current RH and the ideal RH (40% or so), to arrive at the amount of water to be removed, and from there, how much Silica Gel is needed.

Calculation Example:

At an air temperature of 25 °C and Relative Humidity of 75%, there will be about 17.2 grams of water per cubic meter.

In contrast at 40% RH, and the same temperature there will be only 9.2 grams per cubic meter. The difference is about 8g/m3. In this situation, one would need at least 20 grams of Silica Gel per m3 to reduce the relative humidity to 40%, and ideally, one would use more to ensure that any humidity that seeps in is kept under control.

Can a Microwave Oven Be Used to Recharge Silica Gel?

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. It is quite possible that the Silica Gel would get very hot and lose its capacity to adsorb humidity.

Additionally, the porous structure of Silica Gel is harmed when the water evaporates too quickly, which reduces its capacity to absorb moisture.

For best results, we suggest using low heat in a conventional convection oven for a longer period of time.

How Can I Store Recharged Silica Gel?

Store Silica Gel in an airtight container after it is dried out. If there is an air leak in the container, it will pre-absorb moisture from the air.

An airtight bag or container is required to ensure that no moisture comes into contact with the beads. If left out in the open, Silica Gel will quickly re-absorb moisture from the air around it and lose its effectiveness when required. Luckily it can easily be recharged and reused.

FAQ About Silica Gel for Photographers

1. What Kind of Silica Gel Should I Buy?

Different types of Silica Gel
Different types of Silica Gel

It is best that you buy indicative or reactive Silica Gel.

Silica Gel comes in a few different types. Typically they’re sold loose, as crystals, tiny spheres, or in porous plastic sachets that allow air through.

I prefer to buy the loose spheres or crystals because it’s not easy to see the condition of Silica Gel when it is in sachets.

More specifically, I prefer to buy indicative Silica Gel spheres/pellets. This type of Silica Gel is sometimes called reactive Silica Gel.

While they’re difficult to monitor, sachets are very convenient for some non-photographic uses, and to manage humidity in plastic packets.

We recommend that you use Orange Indicating Silica Gel Beads. The orange-to-green type is preferred, as the chemical used to show moisture content is non-toxic and is also less sensitive to heat. The blue-pink indicating Silica Gel contains Cobalt (II) Chloride and is considered carcinogenic in some countries.

2. Is Silica Gel Toxic?

No, Silica Gel is not toxic. However, you should not try to ingest it or mix it with edible items. Also keep it away from children, eyes, etc.

Here is some additional information: The Cobalt (II) 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.

3. Where Can I get Indicating Silica Gel?

Personally, I use 2Kgs of orange beads of Silica Gel.

4. What Precautions Should I Take When Using Silica Gel?

Silica Gel itself is safe to handle and use, but here are a few precautions that you can take when using, storing, recharging, and handling silica gel.

  • Silica Gel should not be handled by children, placed near eyes, or ingested. If ingested, Silica Gel is not toxic and will pass through the system. However, they 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.

5. How Can I use Silica Gel, & Why Is It Important For Photographers?

Silica Gel can be used to remove condensation that is inside camera lenses, and is important when storing cameras in humid environments.

Camera equipment needs to be stored under low humidity or else it becomes possible for fungus to grow on the elements of lenses. Additionally, high humidity also causes rubber parts of the camera and lens to begin degrading.

Silica Gel is, therefore, a very important part of camera maintenance, both in the short and long term. Knowing how Silica Gel works and is recharged is important for photographers to be able to take care of their equipment.

What is Silica Gel?

Silica gel is a naturally occurring compound that is a type of amorphous silicon dioxide. It’s made from quartz sand, a crystalline form of silicon dioxide. The gel form of silica gel is created through the precipitation of a silicon dioxide solution in water.

The silica gel used in industries is a synthetic product created in a laboratory. It is a form of silicon dioxide that is insoluble, porous, and highly cross-linked. The gel is used as an adsorbent, desiccant, and catalyst support.

The main advantage of silica gel is its high adsorption capacity. It can adsorb up to 40% of its weight in water vapor. The gel is also resistant to mold and bacteria. It is non-toxic.

The gel is available in different forms, such as beads, granules, and powder. The beads are the most common form of silica gel. They are round and have a uniform size. The granules are irregular in shape and have a larger surface area than the beads. The powder form of silica gel is the most fine-grained form of the 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.

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Published: August 27, 2016 | Last Updated: November 29, 2022

14 thoughts on “How To Dry Silica Gel”

  1. 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

    1. 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

  2. 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

    1. 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

  3. 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.

  4. Adam R Hagedorn

    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?

    1. 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.

  5. 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…?

    1. 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.

  6. 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?

    1. 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.

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