How to Store and Dry Your 3D Filament: Full Guide | Hacker News Reader

How to Store and Dry Your 3D Filament: Full Guide

syntaxglow.com

50 pointsTheLordKesh32 comments

It all depends of your location and the filament. I had PLA from 2018 that printed flawlessly last year and I had new, sealed PLA and PTEG spools that were brittle or printed a stringy mess unless they spent a night on the drier. The problem comes because there are so much variety and no way to know for the consumer what the composition of each filament is. It does not seem to have much to do with price. This inconsistency across manufacturers, filament types, colors and batches is why people have favorite brands they stick with to minimize the risk.

I have a cheap toaster oven I keep in the garage for drying my desiccant. I just can't bring myself to use anything I'd prepare food in.

I do try to store everything in 4L cereal boxes (often with desiccant), or gallon zip-lock bags. It seems that air circulation is preferable to vacuum sealed if you're using desiccant:

https://www.youtube.com/watch?v=cOHq5kbtlYg

I will say that even in my humid environment (Houston), I seem to have no issues with PLA. PETG and TPU (I don't really use any other filaments yet) absolutely require drying (I have a Sunlu S4, which works well)

What i do, is store all spools in a big sealed plastic tote with some bigger desiccant bags(100g). To dry the filament(even if it's new from a sealed bag) i have a smaller plastic tote that will fit 1 spool with a heating pad(like the ones used for your medical purposes) on the bottom. Add the spool and let it sit fro 6-12 hours on top of the heating pad with the lid closed. Pretty cheap heated filament dryer. Here's the heating pad i use, can be found on Amazon for $14: "Boncare® Small Heating Pad Without Auto Shut Off for Cramps and Back Pain Relief"

But if the lid is closed, how does the moisture escape? How hot does the air get inside the bag?

Moisture gets trapped in desiccant. The hot air drives the moisture out of the filament and into the desiccant.

Not that hot, maybe 50-60C, enough to get the moisture out of the filament and into the desiccant while not melting your spool or filament. Was thinking to add a small fan to it one of these days, connected to a battery and on/off switch, but it's working really good as it is.

Just to add to this, i print mostly PETG and PETG-CF, barely any PLA.

$15 can buy you multiple pounds of reusable desiccant. Buy a few pounds of it in a jug, put a pound in a little cloth bag. Put it in a container with your filament. Done.

I've found an air fryer on dehydrate works well. The Ninja I use controls temp within a few degrees and will happily do so for hours at up to 80C (actual recorded 80C unlike my filament dryer). Also relatively cheap and compact. Worth looking into. Only downside is there's not much space inside the drawer and you have to keep turning it to get an even drying as the air circulation is restricted.

A dryer or similar kitchen appliance is in fact much better because almost all filament dryers on the market trap the moisture inside unless you manually open them.

I find it weird how even today a guide just suggests to leave the lid open when the solution is to buy a device that actually works as advertised.

I have had a project on-the-books for far too long... I have a wine-cooler fridge, that had a broken compressor (already removed), so I plan on turning it into an active drying filament storage unit.

The problem I have is currently "analysis paralysis", and "feature creep" and no time to CAD model the rod brackets to fit into the existing molded-shelves.

Planned features;

- Temperature & humidity sensors.

- Heating element (3d-printer build-plate).

- Active back-channel fan to suck air from internal top of unit down through a plenum to vent in-front of the heating element. In front of that fan intake will be an easily removable desiccant "cage".

- Motor + belts to slowly rotate the filament on the rods.

- Venting fan at the back-top of the unit to extract moist air - plus a servo-controlled vent closure mechanism (iris, louvre? I don't know anymore...)

- External screen and control panel.

But lack of time and very rusty electronics knowledge is slowing me down - so, I store my filament in ziploc bags with re-usable mesh desiccant bags - after drying in a dedicated toaster oven.

I only skimmed for now and will keep a lookout for the mentioned post about the Creality.

But all filament dryers I've seen so far seems to be pure garbage I'd never trust in my home. Which kind of makes sense, they are easy and cheap to make so only bottom of the barrel crap can compete.

But if anyone knows better or have recommendations about proper units / brands please let me know.

I like the one from Polymaker, though that is mostly because it's modular which I needed for a hard to reach space. It claims to have a thermal fuse. https://polymaker.com/introducing-polydryer

The plastic feels solid, but I did not take it apart to check if it has decent crimping or electronics.

If you trust your 3d printer, you could do what the article suggested and use your heatbed.

I have a Sunlu S4, and it works well.

Thanks, the S4 looks really nice. But it seems like they shafted their kickstarter supporters. Risk is of course part of the deal but Sunlu is an established brand and is actively selling the same device they don't deliver to the people that helped to fund it...

https://www.kickstarter.com/projects/sunluofficial/sunlu-fil...

Also, Sunlu (S2) didn't seem to impress that much so overall, not too eager to support / try them out.

Hey, I'm the author of the blog article. I saw your comment and decided to write a detailed critical review of the dryer and write about the specifications. you can find it here: https://syntaxglow.com/2025/02/08/creality-space-pi-filament... or just look at my blog for the latest article :) I'm curious of what you think.

Thanks! And good job, it is quite thorough. I have not done my research and I feel that I completely lack intuition for this. (How much ventilation is needed and how come many of these dryers don't / barely let the humid air out? And inversely how good/bad is for storage considering the ventilation. How good are desiccant bags anyway etc.)

But it looks good, best I've seen.

Would be nice with an electrical teardown just get a feel for the safety (I have no clue about the creality brand).

The drying temps seem high. Many commercial dryers won't even go as high as they're recommending. ABS might be slow to absorb the water, but it seems to hold a lot of it. I was drying a spool and it was the only filament I dried that actually formed condensation on the inside of the dryer. Crazy.

Why not use a microwave for the desiccants? You have them dry again with minimal power, takes only a few minutes. For 30 seconds at a time, styr desiccant around, and start again.

Microwaving is highly effective but can damage desiccants. You're relying on the water evaporation to keep the temperature under control and when it's gone the desiccant will rapidly overheat. Brittle desiccants like silica gel can also crack if you try to microwave them dry too fast. The problem is made worse by the uneven heating of microwaves. This isn't insurmountable, because you can dry a large enough quantity at a time to slow and even out the drying, and stop with sufficient safety margin (desiccant moisture level can by measured by weighing it), but safety margin means you'll need more desiccant to get the same drying performance.

I've dried maybe > 2kg of desiccant in the microwave by now. Always as slow as possible on low power, but a small percentage of beads overheated anyways and turned a very dark color. So now my silica is orange with black dots.

I noticed many of these beads are misshapen and smaller than normal. I suspect they got unlucky with the wavelengths somehow, even though they are so small.

This is exactly what I needed as I'm dusting off my modded Prusa MK3S+ w/ MMU and piles of vacuum-sealed filament.

A missing piece is a discussion on how much problems you'll have if you don't store then properly.

I just have my PLA/ABS/ASA spools on the wall I simply dry then before printing.

I know that the spools can get permanently damaged by moisture... But that seems to take quite a long time as that hasn't happened yet (in my home climate at least).

In my experience, PLA generally is fine in open air. I can't speak to ABS or ASA (haven't used any yet), but I've found that to get the best results from PETG and TPU, I do have to dry it.

I just got a Bambu P1S and dug out some open PLA that was stored in my basement from for a few years and its printing without issue. I feel light exposure is really more of an issue for PLA than moisture.

Its my article and I appreciate your feedback! I will write about this. It technically can get damaged by moisture but it would have to be years in a very humid environment. Realistically not much can happen.

Excellent, thank you.

Just do what I did, and the professionals do.

Instead of buying a filament dryer and having to dry it one of two at a time right before you use it- get a dry box or two. Store all you filament in a nice, dry, state. Ready to go at a moments notice. They're not as expensive as you'd expect.

Yes, you could do that. But some filaments come wet out of the box. Its better to dry it first after unpacking it and then putting them in a storage box.

That's the thing, my storage box actively drys them itself, so I just have to put them in the dry box and I'm done.

curious what brand storage box are you using ?

These are the ones I have:

https://xdry.com/wp-content/uploads/2022/01/302-Small-Footpr...

The solution seems to be, Buy a filament dryer and use it. There, i saved you an entire article.

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