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?
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.
The scientific method, eh? 😄
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.
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.
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.
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.
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”.
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)
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.
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.
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.
