Recharge your Silica gel moisture absorbtion packs

Why is my filament popping, I keep it in a dry box!?

You may not have given it much thought but the moisture absorbent (Silica gel) packs you have stashed inside your dry boxes to protect your 3D filament only work for a few months before they become saturated with moisture.

Unless the Silica gel pack is in a completely sealed package (like a vacuum packed bag) moisture will make its way into the container (containers breath with changing pressure and temperature in the environment), and the pack will absorb it over time. Once the pack has gained approximately 10% of its weight in moisture, the efficiency of the pack drops drastically and eventually become no longer effective.

As an example 300g of gel packs will absorb about a standard shot glass of water from the air before it can no longer maintain 0% humidity inside a given container.

The amount of time this will take depends on the humidity where you live, the heat, size of space that is being dried.

Recharge your Silica Gel packs

Its not the end of the world though, you can get the moisture back out of the packs to restore them to full working order, its easy to do, fast, and you can restore all of your packs in one go.

All you need to do is warm your oven to 100 degrees Celsius and bake the packs for about 90 minutes. You can weigh them before and after baking to determine how much moisture was removed from the packs.

As you can see from these before and after shots my Silicon gel packs lost about 28g of moisture from a 60 minute bake in the oven.


The Silica gel beads themselves can actually be heated to much higher temperatures however the packaging or the colour changing dyes added to some packs can be affected.

What a pain, are there other alternatives?

Most other methods of moisture absorption either cost a lot of money, use a lot of power, or both. Some examples

  • Dehumidifier – not very power efficient, needs to run all the time, and the bigger the space, the worse it gets. Also you are drying a whole room rather than just what you need to keep dry.
  • Air conditioner – as above, but even less power efficient
  • Light bulb in a dry box – an old welders trick, install an incandescent (read: inefficient, that generates a lot of heat for a given wattage) light bulb inside a metal dry box to raise the temperature, effectively dropping the humidity in the container. Normally about a 25W halogen light bulb would be enough for an average dry box, depending on the size of course. Works out to about $40 per year in power.
  • You can try an dry filament before you use it by baking it in an oven. many possible issues as you can imagine.

Leave a Reply

Your email address will not be published. Required fields are marked *