this post was submitted on 30 Jun 2025
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How to dry silica gel (feddit.org)
submitted 4 weeks ago by BennyInc@feddit.org to c/3dprinting@lemmy.world
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I have a questions I haven't found answered anywhere, but maybe someone here can help out.

First, some background:

I have bought this silica gel with indicator a while ago and have used it in my AMS and also for storing my filament in ziplock bags.

I now want to dry some of the silica gel, and have looked at the various options there are. I want to rule out the use of my kitchen appliances, as I am not fully convinced of the silica with indicator being really fully non-hazardous. I also recently bought a Creality Space Pi dryer, which I would like to use for drying my silica as well. Of course I would need to print a container for that, and since I only have PLA and PETG available at the moment, I wouldn't be able to drive the dryer too hot.

Online you can find many different opinions about the ideal drying temperature for silica gel, ranging from 60°C to 145°C.

Efficient energy usage is no big concern for me with this, as my PV modules produce a lot of excess power during the current season.

Question:

What temperature should I dry the silica gel at, and does a longer drying time at lower temperature equal the same results as a quicker drying at higher temperature?

Or does higher temperature actually remove more humidity overall, which a lower temperature can maybe not achieve regardless of time?

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[–] myplacedk@lemmy.world 12 points 4 weeks ago (2 children)

A little tip for when you try out different methods: Check the weight of the silica gel, to check your progress.

For example: Take a container from the AMS, weigh it. Give it an hour in a food dehydrator. Weigh it. Repeat until weight no longer drops. Give it a couple hours or more in an oven that's at least 100 °C. Then weight it again.

Now you know how long it takes in the dehydrator, and how well it works.

Later you can weigh it again, and compare to the weight out of the oven. Now you know how much water is in there.

[–] BennyInc@feddit.org 4 points 4 weeks ago

The scientific method, eh? 😄

[–] elucubra@sopuli.xyz 0 points 3 weeks ago

Great advice! Use two food preparation appliances to heat a material you have no clue about what it offgases in addition to water.

Enjoy your food.

[–] ExcessShiv@lemmy.dbzer0.com 9 points 4 weeks ago* (last edited 4 weeks ago) (1 children)

I microwave mine in a ceramic bowl on 30-40% power (in an 800w unit) for 20-30min, stir and give it another 20-30min. That usually restores them to a dry state and doesn't cause issues with overheating them.

[–] PlasticExistence@lemmy.world 5 points 4 weeks ago

This is the only way I’ve been successful with a microwave dry. For a standard 1000-1100 watt microwave, drop the power down to 20%.

I normally toss them into my food dehydrator while I’m drying filament rolls though so I don’t need another step.

[–] HelloRoot@lemy.lol 8 points 4 weeks ago* (last edited 4 weeks ago) (1 children)

lower temps work partially afaik and they will never fully dry the silica gel. You should aim for above 100°C

If you are concerned about safety have one dedicated oven dish for the silica gel and ventilate your oven and kitchen thoroughly after a session.

[–] morbidcactus@lemmy.ca 7 points 4 weeks ago

I do this, I have a toaster oven that lives in my garage solely for shop use. Have some foil to act as a bit of a heat deflector, seems to work well enough.

[–] Rolive@discuss.tchncs.de 5 points 4 weeks ago* (last edited 4 weeks ago) (1 children)

I use a small hotplate at about 125 degrees and an aluminium baking tray. If you spread the beads out thinly it will dry pretty quickly.

Alternatively you can use an old microwave and that should remove moisture from the silica gel in a matter of minutes. You can easily overheat them though and I would never use that microwave for food again.

[–] elucubra@sopuli.xyz 2 points 3 weeks ago

I do something similar. 1st- Never use something that will be used for food again. There are 15€ used microwaves listed in my local secondhand app, but I live in a small apartment, and I don't have the spare space.

2nd. - I don't do this stuff in the kitchen.

I have a small induction plate, which can actually be set to temperature or power level, and wich is surprisingly accurate! I spent a morning doing testing, and the damn thing would be within 5°C everytime.

I use an enameled pan, which has been retired from food use, and do this in the balcony. I shake it around every so often, with the temp set at 110°C.

It really irks me how a bunch of Youtubers ignore basic safety measures, like using your oven, microwave etc to dry silica, filament, anneal parts etc. We normally have no clue as to the modifiers, additives, etc, or even the actual effects of fumes of the base plastics (maybe there is research, but I haven't seen anybody looking for it)

I'm working on a cheapo enclosure, and already have designed and printed a cheap and cheerful filter, to use EVERY time I print, no matter what the filament. If I don't have hard data about the toxicity of a material heated in my breathing space, I'm going to treat it as toxic.

Safe by default.

[–] GreenKnight23@lemmy.world 4 points 4 weeks ago (1 children)

get yourself a dehydrator for food that allows you to set time and temperature.

you can get silicone trays for the beads and bonus, you can use it to dry filaments.

[–] Vordimous@lemmy.ml 2 points 4 weeks ago

This

[–] elucubra@sopuli.xyz 4 points 3 weeks ago (1 children)

For the love of God, or whatever, people!

STOP recommending that people use food preparation things to heat up material you have no clue about how safe they are. It's likely you are recommending people to poison themselves!!

[–] StrixUralensis@tarte.nuage-libre.fr 3 points 2 weeks ago* (last edited 2 weeks ago) (1 children)

In the case of non-colored silica gel beads you are heating up sand/glass and water (to make it evaporate)

[–] elucubra@sopuli.xyz 1 points 2 weeks ago (1 children)

While pure silica gel should not be very toxic, colored silica gel has compounds that produce that color change.

You'll notice that silica gel is not sold as "pure".

The thing is that none are food grade, so it's perfectly legal to have impurities, and from what I have read, the coloring agents are toxic. Usually not worrying in the amounts used in the hobby, but still, what I warn people is about heating, breathing, etc products or materials which produce suspensions, aerosols, vapors for which we have little research or data.

[–] StrixUralensis@tarte.nuage-libre.fr 3 points 1 week ago* (last edited 1 week ago)

non-colored silica gel beads

Please, reread my comment

[–] cmnybo@discuss.tchncs.de 3 points 4 weeks ago* (last edited 4 weeks ago)

I dry my silica gel in a convection toaster oven at 125°C. I put a temperature probe in the bottom of the tray. The temperature will hold around 100°C while it's drying and jumps up fairly quickly when it's done. It usually takes around 90 minutes.

Don't put indicating silica gel in anything you will use for food, it's toxic. Some types are less toxic than others, but none are completely safe. I picked up a used toaster oven and baking tray from a thrift store and marked them "not for food".

[–] Bronzie@sh.itjust.works 2 points 4 weeks ago (1 children)

I'm not "allowed" to dry it in the kitchen, so I plan on throwing it in the filament dryer with something like this.

It maxes out at 65°C but I'm fairly confident 10+ hours should do the trick.

Luckily I live in a place where it lasts forever, so I'm probably only going to be doing it once or twice per year. My current containers are 3+ months old and I'm at 18 and 14% humidity, according to the AMS's.

[–] BennyInc@feddit.org 1 points 4 weeks ago

Sounds similar to my idea, though I don’t know whether 10h at 65°C would yield the same result as less time at 100°C. Printing such a box with PC or ABS would allow higher temperatures I think.

[–] BuboScandiacus@mander.xyz 2 points 3 weeks ago* (last edited 3 weeks ago) (1 children)

Silica with indicator is hazardous

Yes, even the orange-green ones

Buy some uncolored and use a microwave oven (Warning: only use very little micro power and check every 20 seconds, those things get hot enough to melt ceramic and are a fire hazard)

[–] dual_sport_dork@lemmy.world 2 points 3 weeks ago

melt ceramic

If you're melting crockery in your microwave, I assure you whatever it is you're using is not ceramic. Even the earthenware stuff that cheap coffee mugs are made out of has to be heated to upwards of 1000° C just as part of its hardening process, never mind melting.

You can absolutely get silica gel beads hot enough in a microwave to melt and deform plastic containers, though, including those faux stoneware textured ones. Beware if what you have is not actually Pyrex or ceramic.

I cook the shit out of my silica gel beads in the microwave in an old ceramic pie dish I have no other use for. There isn't a mark on it. Although I will say, you probably want to microwave your beads gently anyway because at high power levels the moisture flash boils out of them fast enough to cause them to split and shatter, or occasionally leap out of the dish like popcorn.