Filament humidity control strategies

Just planning ahead. I watched several YouTubes on keeping PLA dry. There are a bunch of ways to consider, some simple, some expensive.

I would like to start a discussion on the pros and cons of various methods.
I’m not looking for designs for stuff at this point. That will come later.

But first a question. Is it “better” to dry and/or keep dry the filament with temperature control or humidity control?

Discussion points…
0 - Never mind, just leave it alone.
1 - Closed bag or box at room temp.
2 - Vacuum bag at room temp.
3 - Keep it in a bag or box with desiccant at room temp.
4 - In a bag or box with controlled elevated temperature above room temp.
5 - In an enclosure with warm or cool desiccated air in circulation.
6 - Oven dry just before printing.
7 - Warm it on the bed just before printing
8 - Something else??

Any ideas?

Tldr: Mainly 0, but 6 when necessary for me.

This is definitely a preference based question, but from what I’ve seen I’d say that it’s better to keep your filament dry through having it in a box with dessicant (and a hygrometer to know when to replace dessicant).
I say this because it has been suggested that damage may occur from heating filament rolls too many times/for too long (probably depends on material) but this was more of a discussion point rather than a concrete statement so take it with a grain of salt. It’s also possible that you won’t remove water evenly from the roll as the center may take more time to heat or water in the center may take more time to diffuse to the surface.
As for drying the filament, an oven works (I’ve also just put a roll on the bed with a box on top) but a dehydrator with adjustable temperature control is optimal.
Again, this is all preference, I live in a dry enough area and my prints don’t need to be perfect so I don’t bother keeping my filament in a dry box, I just dry it when it seems like it needs to be dried (ie when it begins to get stiff or brittle, or if I have print issues). Some people do prefer drying before each print, especially with very hydroscopic materials, while others just put everything in a dry box and call it good.

I fall in your discussion points throughout the filament lifecycle: 2 when new, then 3 when in storage, then 0 when I’m using it. Never had any problems that require something more.

A lot of this is dependent on where you live and your relative humidity levels.

To dry filament requires heat. Desiccant alone won’t do it. But there’s no reason to keep it at temp once it’s dry.

Some people like to dry filament when they get it just to be safe since you don’t know under what condition it was packaged. I’ve never found the need.

I have a couple 5 gallon buckets with air tight tops that screw on.New (even if still vacuum sealed) and old reels get thrown in there. I have a couple packs of desiccant in each.

When I’m printing the filament reel is inside the enclosure. Some people (especially those in humid climates) set up their reels in a sealed box that the filament comes out of. Some even use a ptfe tube running from the box to the toolhead so the only exposed area is after the filament enters the toolhead. Seems like overkill to me, but again, I live in a dry area.

Whatever you choose to do, I wouldn’t worry overly about it. Learn to recognize the signs of wet filament (brittle, popping sound, zits etc.) and then go from there.

So 3 and a lot of 0 for me.


Likewise although I do have a SUN filament dryer should it be required. Not had to use that yet.

Thanks so far for the replies. I’ll wait a week or so then tally the numbers and report back.

Personally, I do it this way:

  1. new filament, if I need it, I use the filament dryer from Sunlu, there are now and then at Aliexpress for about 30 euros. Hier mal ein Link : SUNLU 3D Filament Trocknen Box Filamente Lagerung Halter Halten Filament Trockenen Sublimation 3D Drucker Filament Storage Box Halter|3D Printing Materials| - AliExpress
  2. after use, I pack the filament in such freezer bags together with the drying pack. Here is a link:ÅMÅŽÕÑ&crid=29PLAGF8VWTFI&keywords=Zipper+Gefrierbeutel+6+Liter&qid=1648874918&sprefix=zipper+gefrierbeutel+6+liter%2Caps%2C63&sr=8-9
    The important thing is that it is the 6 liter bags fit the filament rolls super pure, I press the air as far as possible out of the bag close you and good.
    When I need the filament again I get it out of the freezer bag, it comes directly back into the Sunlu and I print out of the Sunlu.

My conclusion, no clogged nozzles, beautiful prints and the filament lasts a long time even if you have not used it for a long time.

However, have in my study also a maximum humidity of 30%.
Know, however, from a colleague who had his printer in the basement (there is of course a much higher humidity), which he once had big problems with printouts and the filament was simply too moist, it had not stored particularly, but after he also uses a Sunlu dryer and packs the filament in between in the freezer bags, it also works with him again with the printouts!

About the sense or nonsense of the dryer is discussed much and I use it simply because I see that the prints are cleaner. And that is what counts for me. As I said, of course, the question is always in the room where you have your printer stand how high is their humidity on site, etc…

I live in Utah in the US and our humidity here is very low. I’m a 1 most of the time and 2 for longer term storage.

1 Like

Interesting thread. I place my PLA filaments in a sealed box with desiccants and a humidity meter. Average humidity in box is about 30% (as opposed to 55% in open air). So far good prints. So Number 3 is my vote.

OK, it’s been about a week since anyone replied, so I took a tally of the 16 responses.
The winner is, drum roll please,
NUMBER 3 In a bag with desiccant.
Runner up, #0 Nothing, just out in the open.
Also ran, #3 Vacuum bag alone
Only 2 used a heated box (#5) like the Sunlu
And one oven dried (#6) before use and one just used a closed bag (#1)

In my honest opinion, I thought a #3 bag with desiccant was going to “win” as being the simplest (other than just a bag or do nothing). Desiccant can easily be dried in an oven and reused indefinitely.

But I was a bit surprised that #0 Do Nothing came in 2nd. I can see doing it that way if you live in Phoenix, but in northern climes where we can go from low 25% to high 85% in a day or so, not a good idea.

If anyone else wishes to add some comment, please feel welcome.

I find #3 sufficient for most filaments as well (the supplier I usually buy filament from even provides the bags and desiccant packets, no extra charge), and “nothing” works quite well for whatever spool is currently mounted on the printer, even if it stays there for a few months.

I do have a filament dryer (repurposed food dehydrator), but to date have used it only with PVB, which is known to be very bad for absorbing water. I imagine I would use it for nylon as well. PLA and PETG have never required it.

Me again! Looks like we have come to the end as there has been no replies for about 2 weeks. So I will officially close this thread.

In summary, store your filament in a sealed bag with desiccant. Simple and cheap.
Rejuvenate the desiccant as needed.

Thanks to all for the input.


Same here…I live in S. Utah. The humidity is usually around 25%. No drying necessary.

S. Utah as well…I’m looking at my WX station and it’s 81° and 13% humidity in my garage where I print.