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Recharging Reusable Indicating Silica Desiccants

Keeping your plastic dry is critical.  It greatly improves both printer reliability and print quality.  A week ago, we announced our reusable indicating silica gel desiccants, along with some other products.  While we mentioned in the product description that you can dry these out in a microwave to reuse them, we thought we'd give a little more guidance.

How to Use our Reusable Indicating Silica Desiccants

We've just found these handy little cloth bags, which will now be included with any of our desiccants:

To use your desiccants, you have several options:

  • Use the cloth bag that comes with your desiccants
  • Put them in a square or pouch of spare cloth, or in a thin rag and secure shut using a rubber band or zip-tie
  • Punch holes in the lid of an Altoids tin and put them in there (probably not the best among these options as it won't promote the best airflow; but it should still work, and similar setups are how many professional dehumidifier products work)
  • Design and print a clever container to hold your desiccants

When to Recharge our Reusable Indicating Silica Desiccants

Make sure to check on your desiccants often.  How often you'll need to change them depends greatly on the relative humidity in your area, on how air-tight your plastic storage is, and on how often you open that storage to access your plastic.  Check frequently though, and make sure your desiccant hasn't changed color all the way.  If the color change is complete (see below pictures to see comparisons between saturated and unsaturated), your desiccants have already stopped working for you.  Ideally, you want to catch them when they're almost saturated, but when their color still hasn't completely changed.

Here are the two desiccants we sell and a comparison of how they look when fresh versus when they are saturated:

Blue to Pink Desiccant Fresh (Unsaturated) (Left) vs Saturated (Right)
Orange to Green Desiccant Fresh (Unsaturated) (Left) vs Saturated (Right)

How to Recharge (dry out) our Reusable Indicating Silica Desiccants

Take your silica out of its container or bag and put it in a microwave safe dish that spreads the silica out fairly thin (like a normal plate). In selecting your dish, keep in mind that you'll need to collect the silica from it afterwards, so something from which you can pour might make your life easier.

Here is a before picture of some of our orange to green silica after having been exposed to moisture, spread out on a plate ready to be microwaved.

Put the dish in the microwave and set it for a medium power defrost cycle (which offers an intermittent duty cycle, such as a few seconds on, a few seconds off, and so on). Watch it the whole time it is in, and stop it when it appears fairly orange. The time will depend on many factors (how saturated the silica is, how much silica you're recharging, what kind of dish you're using, how powerful your microwave is, what the duty cycle of the defrost setting is, your ambient humidity level, and probably others), but most likely 2 to 3 minutes will do the trick.

Here is the plate of recharging orange to green silica after 1 minute in the microwave:

And after 2 minutes:

Because of their temperature, the drying will continue even after the desiccants are out of the microwave, which brings us to safety...

Be very careful of the silica that has just come out of the microwave, it will be incredibly hot, as will the dish you microwaved them on. Check the temperature of the dish before picking it up and use a hot pad or oven mitt if necessary. Also make sure not to set the plate on any heat-sensitive surfaces. Do not touch the silica while hot. When it is hot it can also become sticky to skin; so hot and sticky you'll wonder why it hasn't been weaponized.

Over time the beads of silica may break down as they are used and recharged. The granules will break apart. You can minimize this by using lower-power cycles on your microwave, by recharging it before it is quite as saturated, or, for maximum life, by recharging slowly in the oven.  Also keep in mind that faster absorption of moisture, such as extremely high humidity and direct contact with liquids can cause the beads of silica to break down more quickly too.

If you'd like to use the oven instead, set your oven to 170F, or it's lowest temperature if above 170F, and add your silica (on an oven-safe dish, of course). All the same safety rules apply, and make sure to keep an eye on it as before.

Once cooled, return to the bag or other container for continued use. As soon as it's cool, it's ready to go again.

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