Vacuum VS Dehydrator! What's the best way to dry filament?

I can highly recommend "Ready Player One" by Ernest Cline.

I recently bought myself a vacuum chamber for a couple of upcoming projects. Since it can boil water at room temperature in around a minute, I wondered if it can also be used to dry 3D printing filament. For this reason I ran a huge test over several months to find out, which methods work to dry filament. I investigated vacuum drying, a food dehydrator, a circulation oven, a huge amount of desiccant, and a couple of combinations. Let me show you what worked and what didn't!

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[CNCKitchen]

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*Timestamps for the impatient*
Introduction: 1:20
Why dry filament: 2:40
Damaging filament by heat: 4:58
Vacuum drying: 5:55
Moisture pickup in open air: 7:30
Food dehydrator drying: 8:00
Storing filament in vacuum + desiccant: 9:55
Do spools dry equally: 10:25
Drying with desiccant: 12:00
Drying in a circulation oven: 12:45
Summary/TLDW: 13:57

[shirolee]

I'm sure you realize this already but you have done the 3D printing community such a service with all of your videos providing real test data and results over all these years. Just amazing!

[KieranShort]

Left in my room unboxed in ambient air, I have PLA filament snap when coming off the spool on its way to the extruder when printing!

[hellelujahh]

This is super informative, thank you!

[FinepixF]

I actually dry my filament in the microwave in low power using defrost by weight mode. Microwaves will heat only the water molecules. Do not microwave for long period, just use short 10s sessions leaving 20 sec to rest and let the water molecules to escape from the plastic. This works great specially for PLA and is good but not great in PETG, I guess is because PLA is derived from corn and PLA molecules give out water more easily. Also water will escape from the hot end when melting the plastic so thats why having a part cooling fan also helps to dissipate the steam produced.

[rynnjacobs]

How about testing Greentec Pro?
The manufacterer claimes it is for applications in the high-performance range and holds up to 160°C even it prints nearly like PLA.
My experience regarding the temperature resistance differs clearly so.

[alexdivision]

I just store my spools under my printing desk and I havent had any issues with my PETG or PLA

[IPlayGames]

Does the oven method produce harmful odors that I wouldn't want in my oven?

[kiigr]

I’m thinking of adding nitrogen as its very dry same as in a hvac system only 1or 2 psi just to push air out ???

[thed_dude]

Reptipro 6000 reptile incubator vs. dehydrator?

[KenzoAkihiro]

It has not been clear to me what is the "best" way to do it because my English is very basic as you can see ... So, what is the best way?

[jasminlevesque]

Nobody is asking about what looks like a E3D toolchanger printer next to the vacuum chamber at 2:23? I'm eager to get a review, it looks so promising! As usual, great content Stefan!

[fragger]

Being a HVAC tech with years of experience dealing with vacuum pumps and pulling water out of HVAC systems installers forgot to keep capped during installation, the fact that a crappy single stage vacuum pump is being used isn't helping.

A 2 stage vacuum pump that can be run overnight without overheating is pretty much required if you want to get a significant amount of moisture out of a enclosed system, as is the ability to maintain high vacuum for the duration.
Also its generally a good idea to have some kind of water trap, either a cold finger or a tube packed with a chemical dessicant, or be ready to change your compressor oil often as the water extracted from the vacuum chamber will end up in the pump oil and damage the pump over time if the water isn't removed from the oil.

If done right, with proper equipment, a vacuum drying setup should be able to drop the moisture content in the filament way lower than a food desiccator can in the same amount of time in most climates that aren't a done dry desert.

I also understand that this testing is being done "on a budget" but its kind of misleading to say the dehydrator is simply better when half the issue here is that the vacuum setup is just too cheap to do its job well.

[muwahh]

I have the same food dehydrator, got it at Aldi. I bypassed the factory temp controls and added a PID controller and a temp sensor. it can go higher and is very stable in comparison to the factory temp control which was swinging around 10-15 degrees..

[hyperspeed]

What are the health concerns over silica with indicator dyes?

Edit: For those wondering, the indicator dye used in silica beads will either be cobalt chloride (blue) or methyl violet (orange). Both of these dyes are toxic and carcinogenic, though methyl violet is regarded as less dangerous than cobalt chloride.
Using small amounts of methyl violet indicator in sealed packets seems to be considered food-safe, but if the indicator is loose like how you buy it in bulk, you could inhale or ingest dust from the beads, thus consuming trace amounts of the dye.

[bradquinn]

You cannot dry stuff (completely) in a static vacuum. Unless you leave the pump running continuously the moisture will reach an equilibrium point within the chamber. When you leave the pump running constantly no equilibrium can be reached as the moisture is constantly being removed. To protect the oil in the pumps in labs you generally use two traps in series. The first bubbles the output of the chamber through sulfuric acid, which takes all the moisture out. The second trap bubbles the output from the sulfuric trap through mineral oil, which traps any fumes coming out of the first trap. Generally these two fluids only need to be changed once a year. Same with the pump oil. You will be amazed at the amount of water that will come off with only limited heating. Generally, proper vacuum drying will move about 1-1/2 times the moisture that air (hot) drying will.

[barrettdent]

One concern I have is people potentially not understanding the amount of desiccant required to actually reduce moisture. Despite your having shown and mentioned it, IMHO a lot of people just won't pick this up. I'd love to see a comparison data showing smaller quantities of desiccant to help absolutely clarify the "sufficient" quantity.

[tihzho]

Many years ago I used to manage a thermoplastic molding workshop where we heated plastic sheets enough to be formed on a mold using vacuum. Some plastics are hygroscopic meaning they absorb moisture such as PETG and polycarbonate (lexan) being the worst. In order to mold PETG or polycarbonate sheets thicker than <3mm we had to dry them in an oven for certain period of time and mold them within a certain period of time. If we attempted to heat these sheets without drying small bubbles would appear all over the sheet from absorbed water vapour - <3mm sheets were thin enough for the sheet to dry out if heated slowly.


If you're using a vacuum pump to remove water from materials you need to use a vacuum pump with a "gas ballast" valve which allows a vacuum pump to pump condensable vapours. If your vacuum pump does not have this feature than water vapour will condense and mix with the oil. If the amount of water vapour is small eventually it will be purged from the oil, however if the amount is too high the water and oil will make an emulsion like mayonnaise and you will damage the pump. Therefore if you're using a vacuum pump to dry a substance use of the gas ballast valve is essential, however if this is not available running the pump with the inlet blocked for an hour or so. If the oil is looking whitish change the oil immediately and flush with clean oil.

[varukasalt]

What's the issue with indicator? Haven't heard that before. NOT saying there isn't an issue, just asking for more info. First time I've come across this.

[TheDgdimick]

You could consider this post a "peer review" of your findings. TLDR: I found results consistent with your findings.
I've been running theses "drying" tests for over 6 months now and I don't think drying water is the issue. I've used ABS. ABS+, PETG, PLA and PLA+ in my tests, sorry, don't have the "exotic" filaments you have. I have not seen even ABS absorb much water when submerged for 7 days, that was above a .2% change, (2g of weight using a 1kg spool.) What I think needs to be tested, is what chemically happens to filament as it ages, and how applying heat to the filament changes the filament. My thinking is that heating the filament causes some gassing, chemicals in the filament to be released due to decomposition of the filament. Since I don't have the ability to sample the gases, this will only continue to be just a "guess".


- My method of testing is to weigh the filament as soon as it is unsealed, dry the filament at 135F for 5:30 hours, re-weigh, submerge the filament for 7 days 100% under water, remove the filament from the water, spin dry the filament in open air for a few minutes to remove any extra water that may be trapped in the spool, weigh the filament, re-dry the filament at 135F for 5:30 hours, re-weight the filament, and record my findings. If all I see is a .2% change in the filament, then I'd think water is not the issue.
Does anyone else have any test data to share? So far this all has been subjective data about drying and there is still lots of research to be made - WITH this said, I still recommend drying where there is a filament issue, what ever heating the filament does, it seems to improve print quality.


I'd like to see more of these types of tests, however, I'm not sure if you can get the test equipment you need, or if there' s a "market" from your watchers. My guess is not everyone else is a nerd.


Thanks again for a great video.