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

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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]

Don't forget to share this video on Facebook, Reddit, Twitter and other social media! *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

[@f1ggyc]

Add your timestamps to the description and they show up on the progress bar now its a cool new youtube feature

[@avaviel]

Damn the summary goes straight to an ad. I'd appreciate it if you'd have a summary with data points that are actually useful. I don't mind the ad, but not having the data there is frustrating. (Yes, I get it, free thing and you need to make money.) Today I happen to be in a hurry, and I know your videos take about ten minutes to get to a conclusion.

[@krazed0451]

@@avaviel Click the TLDW timestamp... Then you only have to watch the conclusion to get the requisite information.

[@CossieNissse]

You should heat up the material before you put it in the vacuum chamber to get the best result. Look at this video. m.kzbin.info/www/bejne/op-5m6ureMhnjcU

[@CossieNissse]

Or use an desiccant dryer with dewpoint lower than -20c m.kzbin.info/www/bejne/nXype4OwnpV9j8k

[@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

[@AU12]

Or you could always use an oil-free vacuum pump

[@tihzho]

​@@AU12 Yes, depends on the degree of vacuum required.

[@hyperspeed1313]

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.

[@goguyted]

Thank you, that was Exactly my question (I use blue indicator) I will be throwing it away immediately and buying non color indicator.

[@DrMarcArnoldBach]

Cobalchlorid is a salt… there is nothing to worry as long as you do not eat a lot of it.

[@tildey6661]

@@DrMarcArnoldBach whether or not a compound is a salt is not an indication of toxicity… Cyanide comes in many salts, for example. As does lead

[@4b5urd.]

@@tildey6661 you are correct, but I don't believe that is what he is saying. He states his opinion that the risk is minimal or non existant unless you have some excessive physical contact, such as eating it, with the compound in its salt form. The last part of his statement indicates that it is indeed toxic "as long as you do not eat a lot of it". What it being in a salt form, or any toxic compound being a salt for that matter, has to do with the risk it imposes I'm not really sure. Perhaps he is insinuating that under normal circumstances it is not a volatile compound and your not going to encounter it in the air, i.e. not being a volatile substance, not going to be in the air, not going to sublime, turn into a gas, no vapors, thus your not likely to come into contact with it under normal circumstances. That theory is a long shot and seriously flawed however, i'm not going to look into the vapor pressure and vapor temperature to begin to decipher what his logic was and its based on my assumption that he has limited education and training in chemistry. I could see someone without a strong understanding of chemistry thinking that there is no exposure to the compound unless you physically touch it.

[@expression3639]

The orange-green ones I bought say they do not contain cobalt chloride. Now whether what they actually contain is toxic or not.. no idea.

[@fragger56]

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.

[@danuw3lls]

This..

[@DisorderedArray]

I use 2 stage rotary vane and turbo pumps regularly in my lab, and drying solids is always done under red pressure rather than dessicants, it's considerably faster and produces much dryer material. A dessicator might take days to achieve what just an hour of a few micro bar vacuum manages. Although as mentioned, overnight drying on a vac line gives best results, especially for bulk materials.

[@TrevJonez]

I demand a recount! I've had way better results with 12 hours of vacuum pump running than 24 hours in a food dehydrator. I always run mine with indicating desiccant visible through the lid so I can clearly see when it is "ready" to come out. My experience was with an even worse looking cheap pump that I put good oil into. It gets hot, but seems to work. I just change the oil once it starts looking milky.

[@RossReedstrom]

@@TrevJonez As frager56 mentioned above, a water trap will save you a lot of oil changes: use a long clear tube full of indicator desiccant, and you can watch the color change, then you know when to stop and bake the desiccant.

[@edwardpaulsen1074]

I fully agree with your assessment but I think Stefan was catering to the 3D printing community that might not be able to afford a good two stage vacuum pump for merely drying out their filament. I also concur with having a desiccant or other means to absorb the shed moisture and keep it from getting sucked back into the filament once the vacuum is released.

[@donamills]

Some of the most comprehensive testing regarding 3d printing come this channel. Hands down. Thank you for all your hard work.

[@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!

[@CNCKitchen]

Coming soon!

[@stevehazim5823]

@@CNCKitchen Can't wait! I'll see you in the next one 😁

[@TheJkilla11]

@npgoalkeeper _ wow, good to know the internet police are on the job.....

[@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!

[@marcozacarias1675]

Absolutely!

[@muwahh98]

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..

[@littlecube141]

Just curious, how did you do this?

[@3-DMonkey]

@@littlecube141 same how???

[@stroopwafelfalafel]

How??

[@muwahh98]

@@nxxxxzn kzbin.info/www/bejne/iH-5aXlrq5ZmjMU

[@muwahh98]

@@nxxxxzn not my video but similar concept can be applied to any heating system. The controller is cheap on eBay or Amazon

[@muchtall]

I've been waiting for this one! Great analysis. I'd been wondering for some time if vacuum drying was worthwhile. Thanks so much for doing the footwork!

[@CNCKitchen]

Glad it was helpful!

[@super_slo]

Have you tried combining them? Vision miner is selling a kit that involves an oven and a vacuum pump/pot with instructions to bake, then vacuum and agitate for maximum affect. Awfully intriguing, but I don't have anything that will print peek - which is their target audience for the several hundred dollar setup. Seems like it should work for lesser materials, but I don't have a vacuum pump/pot to try it out with. Thanks for all you do!

[@bradquinn4161]

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.

[@termivan]

how do you know when to replace the sulfiric acid

[@bradquinn4161]

@@termivan Generally you just make a line on the container (preferably clear) at the height of the fresh sulphuric. Once it doubles in volume it is time to change it. Usually that works out for us to be about once a year, but that will depend on how much you use it.

[@goguyted]

@@bradquinn4161 excellent, I see that my job (assembly shop) has about a 500g chamber of dessicant in line to the industrial pump, I am considering all these options to help prevent oil contamination in the future, where might I be able to shop for such accessories?

[@bradquinn4161]

@@goguyted We used to use two of the used (and clean) acid bottles(2 litre?) with some of the red vacuum sealer. The bottles are shatter proof due to shipping regulations. If you have a local lab they MAY just give you a couple.

[@barrettdent405]

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.

[@White000Crow]

What if the filament attracts moisture more readily than the desiccant? Wet desiccant will hydrate the filament. I will vacuum bag with desiccant after the filament has been dried overnight.

[@jamesgreen4965]

​@@White000Crow If there was a filament that attracted moisture better than desiccant, we would be using it as desiccant instead of silica gel.

[@reddragonflyxx657]

​​​@@jamesgreen4965We actually do use a lot of dessicants aside from silica gel (zeolites, activated alumina, molecular sieves, calcium chloride, sulfuric acid, clay...) you can even find polymer dessicants intended for injection molding (which could theoretically be turned into filament). Which dessicant is best depends on the use case. Sometimes loose beads, dust, or sulfuric acid can cause issues. Sometimes you need an indicator for replacement. Sometimes you need extremely low humidity (some types of silica gel aren't particularly good at low humidity). Sometimes you want a dessicant wheel which regenerates (releases water) very easily. Sometimes you want a dessicant that works at high temperatures, or very low temperatures.

[@coledavidson5630]

​@@White000Crow that's not a realistic scenario. You should definitely use desiccant while drying

[@White000Crow]

@@coledavidson5630 I use filament dryers now.

[@MichiganMaker]

great video. I love the idea of weighing. I was surprised how much water had been absorbed.

[@schallmaurer]

The amount of detail is impressive. Every video is like CSI or better FSI FilamentSceneInvestigation 😉 Fun to watch and aducational af 👍

[@madmax1419]

My best results of drying filaments are in a dehydrator for vegetables and fruits. It cost low money, uses a little of electric power and helps drying my filaments in 1, maximal 2 hours. I mostly print PETG and Nylon with cf or gf. For my dehydrator I printed a drying chamber in which I can dry 3 rolls of filament at a time.

[@amedeekingchef6552]

I dry my filaments in food dessicator for some hours after each use and store it in clothes vacuum bags with dessicant. Perfect!

[@Berkana]

Stefan, try doing this: do the vacuum + desiccant drying, but wrap your steel vacuum chamber in an electric blanket set to a low temperature that would be safe for extended exposure. I think the combination of an electric warming pad and the desiccant + vacuum over night might give you the best results.

[@alanb76]

Still a useful video, even after a few years. Active alumina desiccant brings the RH much lower than Silica Gel, has higher moisture capacity and a longer life. The interactions between moisture and the filament are more complex than covered here, and not all of them are reversible, depending on the polymers involved. PLA in particular doesn't return to the same state after heating, so there is a lot more to investigate here in a future video. Proper dry storage is important and just drying the material after improper storage does not always result in a good result, and brittle filament is one result that we commonly see. Combining heat and vacuum is significantly more effective at removing moisture quickly. Lots more for future investigations!

[@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.

[@edwardpaulsen1074]

There is one major problem with your test method... liquid water has a very strong cohesive force and does not like plastic in the first place... it is not as likely to penetrate as the individual molecules of water in a high humidity environment. Your water was also likely to be room temperature (or lower) which will also affects absorption. As an example, drop ramen in cold water and hot water and see the difference in time it takes for the ramen to get "soggy". Humidity is measured while water is in its gaseous state, *Not* when it has condensed to a liquid... the temperature that it condenses is the dew point. A far more appropriate test would be to "steam" your filament for an hour and measure the weight change, then try drying it.

[@TheDgdimick]

@@edwardpaulsen1074 Ed, Thanks for the reply, I was hoping someone would reply to "check" my work, however, you have only brought more questions - I like that! Since my numbers are very close to the ones posted in the video, how do you think steaming would be a "real world" test? These tests are to determine the normal absorption of water, during normal use, not try and force as much water into the filament as you can. To go back to your Ramen example, we are trying to measure water absorption with it sitting on the counter, not being boiled in water - We leave our filament out in room temperature air, not in a hot sauna. I'm sure I could be missing your point. Thanks.

[@smportis]

meance perhaps he is saying to get maximum water absorption, use steam. It would be interesting to see how different the values would be. I live in the southern US, so high heat and humidity are a factor here.

[@TheDgdimick]

@@smportis Think about what you say - Steam is normally created at 218 F, you your thinking heating filament PAST the temperature that most filament is extruded at is what he's saying? An open container of water will normalize at the temperature the humidity will be in the area - room temperature is 80F, the humidity is 80F. Any other tests are not valid because you are not simulating the normal environment filament will be exposed to. - Even the water submersion is an valid test, unless you store your filament in the rain.

[@TheDgdimick]

@@smportis Soory it's early in my day, so I should have used C instead of Water boils at 100C/218F, and filament is extruded ate 212C, TWICE what water boils at.

[@MickHealey]

I'm only 3 years late with my comment 🙂 After the vacuum drying is done, I think that the vacuum vessel needs to be vented to atmospheric pressure using a dry inert gas (Nitrogen or Argon). Venting the chamber with potentially moist air would reintroduce moisture back to the filament.

[@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.

[@Doping1234]

The blue-pink indicator is cobalt-based. The yellow-blue indicator should be fine. I wouldn't be too concerned about either if you don't plan to eat it ;) EDIT: Turns out yellow indicator has some variants, those with methylviolet are "concerning". www.giebel-adsorber.de/images/unternehmen/neue-produkte/GIEBEL-FilTec_Unbedenklichkeit-Silicagele_DE.pdf

[@the_arcanum]

The orange one is safe, the blue one contained cobalt chloride and has been banned in the EU since 1998. The orange one is also more expensive. www.agmcontainer.com/blog/desiccant/indicating-silica-gel/

[@ninjamaster963]

Blue silica gel uses cobalt(ii)chloride which is carcinogenic. Orange silica gel uses methyl violet which is toxic, but not in the concentrations found in commercial silica gel. Concerns with methyl violet are more likely to do with water contamination due to improper disposal

[@Basement-Science]

Yep. The main concern here is probably contaminating your kitchen's oven, although the plastics themselves are probably outgassing more harmful stuff. Ideally you want a separate oven that is not used for anything food-related.

[@the_arcanum]

@@Basement-Science Or you can dry it in your 35$ dedicated dehydrator that also dries filament. That works too :)

[@Docanza]

Random question, how do you know how much of that water is getting removed from the filament, not the spool itself? Each plastic spool is made of a different material, that may be soaking up water and skewing the results?

[@dl200010]

I have been only using PLA and PETG. I store it in a vacuum bag with desiccant. When printing I put it just on the rack on the machine.

[@Nero_XY]

I store all my filament in these same Ikea boxes with desiccant and also print out of the Spannerhands wall-filament-box (also filled with desiccant), never had any problems with moisture :)

[@dextrian]

have to say 2 things: 1) GOOD JOB, very well done, congratulations. 2) Also a good selection of materials and a very good plot of the results, I was aiming for Petg, and now I know what I will do. 3) For the first time, i really want to test audible XD

[@kylek29]

Tip for those in the US, you can get cheap desiccant at many stores by buying the 'crystals' type of cat litter which has the sole ingredient Silica Gel. Comes out to less than $1/lb usually.

[@CNCKitchen]

Tried that in the past but it didn't work for me, unfortunately.

[@TalpaDK]

They are also available in Denmark, and works fine for me... and so very cheap

[@TalpaDK]

@@CNCKitchen ​ It didn't work even after regenerating the cat litter? (I haven't needed yet with mine)

[@flymypg]

There's another step in the drying process: The hot-end itself. That is, how can moisture be better coped with during the print process? When I got my Sidewinder X1 v4 I did several side-by-side tests with my Monoprice Mini Delta (MPMD). One of my biggest issues with the MPMD was its behavior with wet PLA filament, especially the very inexpensive PLA I use for draft prints, which I suspect was wet when it was made. This filament would sputter, hiss, spit then ruin the print. The worst offender was some low-end satin metallic filaments (all colors - gold, silver and copper) that the MPMD was unable to print without much spitting, then clogging the nozzle with the melt back-flowing into the heat-brake. After completely rebuilding the effector three times I gave up using those filaments on the MPMD. The same filaments printed PERFECTLY in the X1! I was beyond shocked. My theory is that the much longer melt zone of the Volcano hot-end was allowing the steam to escape out the top rather than being forced out the nozzle. Being direct-drive this was difficult to see during the print (vapor condensation was sometimes visible in the MPMD Bowden tube). So, Stefan: Do melt zone length, hot-end temperature and filament feed rate / nozzle diameter (melt zone pressure) help mitigate filament moisture issues? If so, in which direction and by how much? FWIW, I no longer bother drying my PLA or PETG, and I don't use desiccant. I do try to store spools in zip-lock bags or sealed plastic tubs, but I always have a spool on the X1 with no such care. I try to use only new spools with the MPMD, and run everything/anything on the X1. Edit: Typos.

[@jmtx.]

Awesome testing! Good to know the simple dehydrator is the perfect thing to use for the more common filaments.

[@pizzablender]

Or, if you have time, a closed box with silica gel.

[@jmtx.]

@@pizzablender - Desiccant will absorb ambient mositure but won't draw it out of the filament itself.

[@matneu27]

I also bought a set of vacuum pump and a pot. To dry it the filament also needs to be warm. But the critical point is when you float the pot after vacuum to open the lid it soaks all the ambient air with moisture back in. To make it professionally you had to do the floating after vacuum with dry nitrogen. At last I keep my non pla filaments in boxes like yours with silica gel pearls. On top I placed in each box a wemosD1 mini with a a humidity probe which tells me what happened inside without opening the box unnecessary.

[@johanneshass1614]

In Chemistry we used vacuum desiccation while also putting a bowl of fuming sulfuric acid into the chamber - sulfuric acid is highly hygroscopic.

[@CNCKitchen]

Contact with the filament and the fuming sulfuric acid will probably set it on fire? 😅🔥

[@johanneshass1614]

@@CNCKitchen Only if you add some nitric acid - though that may also yield a friendly visit by the bomb squad...

[@mckidney1]

TLDW needs to be in every video :D Such a wonderful feeling at the end :)

[@CNCKitchen]

Some people hate repetition, though ;-)

[@AndTecks]

Some people call it the conclusion. Same thing

[@AtomicZepherino]

Is it possible to elaborate on the health concerns of color change dessicants? They are commonly sold and have instructions to regenerate in the oven, and it would be interesting to know of potential risks.

[@nsboost]

I have a small vacuum chamber that I could fit one roll of filament in. Wonder if the combination of heat and vacuum would do the job better

[@PeterAcrat]

Thank you for your high-quality work Stefan👍

[@AR-xy4jy]

Great video with a lot of detail. I usually store my filament rolls (i use mostly PLA) in the plastic bags they came with. I add a perforated transparent film-container filled with dessicant to each bag and close them with ordinary bag clamps. Benefits are: less potentially humid air in the bags compared to plastic boxes), doesn't require much space, is relatively air-tight, costs next to nothing.

[@licensetodrive9930]

I bought a cheap temperature controlled food dehydrator to dry out my 25+ filament reels and store them in 3 waterproof tubs that have 0.6kg of silica gel beads in each one (orange bead=dry, dark green=needs drying out) The difference in my PLA isn't very noticable but it is worth it, PETG is less stringy, and TPU is wow, check this out: 2 prints from the same TPU reel, guess which was printed after the filament was dried out: haku.co.uk/pics/WetAndDryTPU.jpg

[@davepost7675]

The driest place in your house is your freezer, that's why ice cubes sublimate in the freezer if they are left there a while. I often wondered if the freezer could be used to dry filament.

[@nicolasr.5870]

As usual, outstanding and methodic job !

[@brycefitzpatrick8353]

I use vacuum sealed reusable bags for storage with desiccant packs, then dry in a food dehydrator for several hours before printing. Works like a charm!

[@jordanl7489]

Wide size of bags do you use for vacuum sealing? It's hard time find a sealer that will seal past 12" for under $400

[@Ale_giro]

@@jordanl7489 ebay. 15€ for 50pieces disposable bags, but if you seal and cut well, you can reuse up to 3-5 times. 35x35 for me are good enough.

[@jetblack2602]

@@jordanl7489 You can use the bags which are normaly used for vocuum storing textiles. They are cheap and you can use a normal vacuumcleaner.

[@jonathanneill6107]

Industrial dryers have two desiccant beds, a heat source and a condenser. The cycle switches between beds every four hours. One goes through a drying cycle while the other goes through a recharge cycle. Hot Air is moved from the drying bed, through resin and then condenser before going back to the drying bed. Plastic resin needs to be dried close to -40 dew point before extruding. 3dp probably doesn’t need to be this dry which is good because it’s not easy to accomplish on a small scale affordably. Please get a moisture meter.

[@luciankristov6436]

I just print all of my nylon based filaments right away. I don't even bother keeping it around. I print gun parts with polymide COPA. I set it up in my homemade dryer box with lots of silicate. I get about 18% humidity and print out the whole roll in a few days. Holds up just fine . However I really want to print with polycarbonate. wouldn't it be nice if high temp printers were affordable lol .

[@Torsan1977]

Cool as always! Including a control in your experiments would provide some extra value, but perhaps not necessary.

[@austinekenstam744]

What about heating the filament in the food dehydrator then (while still warm) vacuum pumping? Vision Miner was using this method in a video from the 3DPrintingNerd.

[@CNCKitchen]

I usually do that before storing it, though I didn't really notice that it helped in any way.

[@AltitudeOutlaw]

@@CNCKitchen I think you should have done the test with warm/hot filament. You need energy in the vacuum to facilitate evaporation. If you put in "cold" spools, there's not enough energy to dislodge the water molecules. Ideally, you'd have a heating pad inside (or at least on the bottom of the chamber on the outside) that imparts energy into the spools while under vacuum to facilitate the evaporation. Without this added energy, the water is not going to go anywhere.

[@luckybenni3914]

sooooo long waiting for this video - u rock

[@Noughtta]

I ran into this very issue with a box of PETG I had laying around I forgot about for around a year. It would print fine like you said with a bit of excessive stringing but once you placed load on the part it would break apart like glass. I ended up wasting a ton of time trying to trouble shoot it.

[@Deqster]

What about microwave drying? Thats something I've tried with old TPU parts that tend to get stiffer after months of exposure to moist air. They got more flexible again immediately (after they cooled to room temp of course). That would be a good meeting to examine.

[@leonardovargas4489]

In the laboratory, vacuum microwave ovens are used to dry out certain types of material. I always keep all my materials in boxes with desiccant

[@edwardpaulsen1074]

Since a microwave works by heating the water molecules, that could work... but I would worry about the uneven heating going over temperature and deforming some parts. Microwave ovens have turntables because of that uneven heating issue. I wouldn't recommend it for that alone, much less any additional out-gassing of the plastic in a place you cook food... unless you want to dedicate a microwave to that (along with the aforementioned issues)

[@xKatjaxPurrsx]

That works really well with bronzefill filament.

[@leonardovargas4489]

@@xKatjaxPurrsx Any metallic filament to tell the truth, kkkk

[@Jeff121456]

Why not use a printer's heated bed to heat your vacuum pot? Heat with the lid on but no vacuum (for maximum heat transfer) until the spools get to a good drying temp. then pull a vacuum.

[@user2C47]

Glad to see that at least one other person uses their printer as a hot plate.

[@defenderred1212]

Probably more of a laboratory thing, but using a gas spectrum analyzer to sample the off gassing would help identify the chemicals being released. That would be a helpful data set to have in case additives in the polymers begin to off gas with the water vapor.

[@BRUXXUS]

Wow! What an incredible amount of work! I'm so happy to have access to someone like you that puts all these tests together and publishes the results in concise and fun ways. :D

[@joea3728]

It takes 1 BTU to change 1 pound of water 1°. It takes 144 BTUs to change the state of 1 pound of water without changing the temperature 1°. When using a vacuum, that 144 BTUs is retained by the remaining water. Cooling it down. Eventually it might freeze. Which makes it more difficult to change the state. The vacuum pump that you're using is not sufficient for the application. You need a commercial vacuum pump. The kind used in air conditioning service, or better. 29+ inches of vacuum is needed. The amount of heat that can get into the plastic from the outside also makes a difference. In a vacuum chamber, heat cannot be transferred through the air, Since there is little air for heat to transfer through. If your vacuum chambers clear, you might try placing a heat lamp around it. Also, when you break the vacuum using The moist atmosphere, that moisture in the air is going to be pulled deep into the plastic. Dry nitrogen is recommended but expensive. At least you can pull the air through dry desiccant instead. A dehumidifier may also make a difference. Keeping the air as dry as possible. If the air is dry, moisture cannot get into the filament. Unfortunately the dryer the air, the more static will build up. This could be hazardous to the electronics. Stay safe and happy printing.

[@DCBpower]

Warming the filament prior to vacuume will drastically remove humidity. (Essential for engineering plastics.)

[@Fly_High_FPV]

Seems storing my rolls in Vacuum bags with desiccant is a good practice. I dry with a convection oven if my TPU gets ridiculously stringing

[@baitsharkbuckets]

I found this video valuable. Thank you! Keep up the good work!

[@brucewilliams6292]

Your scientific pursuit of all your topics is greatly appreciated!

[@AmaroqStarwind]

Question: "Vacuum or Dehydrator?" Short answer: "Yes." Long answer: "Use both. Freeze-driers are a good example of this."

[@Fm-ss4uj]

I've found that a vacuum chamber with a heating mat on bottom works much better and dries significantly faster compared to the other methods or without the heating chamber its night and day difference try it out well worth it cuts drying time at least 40 percent faster

[@karoo_bushman6880]

Cool! What heating mat would work? I find these metal vacuum pots all over amazon, with cheap oil pumps, would that work? Alternatively a good oil-less two-stage pump?

[@BlindedJacob]

What is the energy consumption of the compared methods? Or efficiency in terms of costs in euros?

[@CNCKitchen]

250W continuous for the dehydrator, 150W for the vacuum pump. Please do the math ;-)

[@OverthePantsClayHJ]

I am wondering if you could use radiant heat to warm the filament while under vacuum. Maybe with a food warming IR bulb. You would get the dehydrator's thermal effect on top of lowering the boiling point of water with the vacuum.

[@j.hankinson7803]

Thanks for posting this. I dry wood frequently in a vacuum kiln I made. The two key factors are the amount of vacuum, and heat but not too much. Your little vacuum pump should be able to deliver adequate vacuum. I automate my kiln with a simple mechanical timer turning the pump in every 90 minutes for about twenty minutes. I also put a one way valve in-line because the pump doesn’t maintain vacuum by itself very well when turned off. I use heat mats that don’t get warmer than 40C. When the temp in the material reaches about 36C the water really starts to come out. Because the heat transfer is by conduction the maximum thickness for best results is about 100mm. I can dry wet wood at 55%+ moisture to nearly 0% in 3 days. This is 120 year old technology for wood. A German friend has found a 25W motorcycle seat heater to use in a vacuum chamber similar to yours. Sandwiching the plastic rolls between heating pads will give you the best success and speed. You could also try just putting it in a sunny window. However, considering all the messing around, in the end your cheap desiccant in a decently closed plastic container seems to me to be the best option for most plastics.

[@warlockd]

Do you think heating the filament in a food dehydrator to say 40-50c then stick it in the vacume the way to do it then? Mabye I can screw in one of those water heater elements in the center.

[@j.hankinson7803]

@@warlockd I imagine you’d get a bit of a head start but you still need to keep the stuff warm, about 40C I’d guess, over a day or so under 26.5mmHg vacuum at least - more if you are closer to sea level.

[@BMathiesen]

This is SUCHHHH a beautifully thought out video and executed so so perfect! Thank you for all this information! Was nice getting all the info I was wondering in one video instead of watching 3-6 different videos haha

[@joelevi9823]

I would suggest that vacuum is less effective since the air take up the moisture he can then stay like that in the sealed chamber..the other is letting new air in

[@deuterium8236]

Stefan nice video with good information. I got great results from a vacuum drying system that I built for drying nylon and carbon fiber PC but also found it was great for ABS, PETG etc. I noticed that extruding smells are also greatly reduced using dried filament. My vacuum pump is a small heavy scientific 50L/minute two stage oil sealed model. The ultimate vacuum (no flow) is 0.1 or 10 pascals if the ballast valve is open. When the ballast valve is open, the bleeding air removes condensates from the oil. Have a smile at my $50 stove top pressure cooker vacuum chamber that is big enough for 2 spools (fresco brand but the cooker is sold under many names). I only had to invert one threaded pressure safety relief valve so it would seal under vacuum. I designed 3 printed parts, and using a refrigerant diaphragm valve that seals to the lid with O-rings I was done. A removable flexible stainless-steel natural gas appliance hose connects the valve to the vacuum pump with another printed part. Unfortunately, I only have a 1gr resolution scale to measure any weight change. Instead as a dry indication test, I print clear filament at the maximum recommended extrusion temperature then look for bubbles in the purge line using a x10 magnifying glass, and with PC I don't get any in the first 12 hours after vacuum drying. With a non-scientific vacuum pump which produces less vacuum, I would feed a very small amount ballast air directly into the vacuum chamber but only while pumping to reduce the chamber humidity and the pump oil moisture. -Peter

[@Damjanhd]

I like to see video how to create and print a power supply front plate to mount on it display, buttons and all stuff and over that dark Plexi glass, hols created with CNC milling machine.

[@knifeyonline]

12:59 I think the english translation for circulation oven, is fan forced oven. Also most materials only need to be dried at 55C and not 70C. If that's not working well because you live in a humid environment, put your dehydrator in a bigger box (close to air tight) with desiccant (kitty litter works 😉).

[@jasonhurdlow6607]

Convection Oven

[@Auggie246]

Doing the lords work

[@adamd0312]

Please could you do a video on comparing the combination of retraction speed and retraction distance and perhaps experiment with finding the best ratio? Your videos have been a great help but I don’t have the time to test these things in depth myself. Thanks

[@micahjardine8456]

Man I wish my oven was that clean.

[@sashausb1]

i am intrested what would happen in heated vacuum chamber

[@Ryman158]

Lol love the repurposed BHO kit lol

[@jonnyhifi]

2. FYI Stefan - I emailed Taulman a couple of months back asking them for their advice on best vacuum drying practise esp for taulman 910 (a nylon) and other of their functional filaments explaining I was using a small vacuum pot like you, with a PID controlled heated mat underneath the vacuum pot and filament, with loads of dry desiccant inside the vacuum pot - and this was their reply - “With a vacuum unit about 8 hr's max.....usually around 4 at 40C and a good vacuum. Max temp should be about 60C....sometimes you can make the line a bit "oblong" as it's wound tight in some spools. As you're doing, the key is desiccants in the dryer....Most don't realize this is the main KEY as otherwise, you're just using hot and humid air and it won't really dry well”.

[@cellularmitosis2]

Thank you for mentioning the indicating silica gel health concern, I didn’t know about that!

[@ThantiK]

Now I have a reason to have a vacuum pump! XD

[@N00T0N]

I have transparent PLA and I store it in my room. After 1 day of heavy rain, it clearly shows air or water (really don't know which one) bubbles inside the filament.

[@lyriccall]

Have you tried to store filament inside a vacuum bag with dessicant? The reusable bags

[@BLBlackDragon]

I live in a very humid region (40%+ ambient). This is very helpful information.

[@richardphatthenguyen195]

The problem when vacuuming alone, is the temperature drop since you take out the higher level energy molecule and leaving the lower energy molecule to cumulate, which then requires to succion even more vacuum. The solution is to do both. I use to have access to a cole parmer vacuum oven, and these thing works very well, you put it about 4 hours and print quality were as good as new. I guess leaving the vacuum pot in the sun should also work for petg or abs.

[@skandranon314]

I use a dry box with desiccant (2-5#s per box). Considering adding in a lowish constant heating element. Wondering if adding desiccant to active heating like with the food dehydrator would improve the results.

[@matschase]

What's the health concern regarding silica with an indicator? Never heard of that before

[@surmur]

I wonder why you didn't try silica in vacuum chamber? That and maybe 50C heat would work wonders in few hours?

[@SteveH-TN]

thanks for sharing

[@masterrc123]

I happen to live at a 10000' elevation and the best thing is there's no moisture in the air for my filament to absorb 😂😂

[@eyes21st]

Thanks

[@mp6814]

Excellent! Thanks!

[@T3KFTW]

My nylon straight out of the package was boiling out of the nozzle I could hear snaps and pops of water rapidly vaporizing

[@zaccb1566]

If you put silica gel desiccant at the bottom of the vacuum chamber and put it on low heat on a hot plate, you could probably get it much much drier.

[@mordiev]

I like your videos and how thorough you are in your testing. Is there any chance you can do some testing about how effective desiccant is depending on how much is used and where it is located in the dry box? I have recently become convinced that desiccant at the bottom of the dry box doesn't work as well as desiccant located at the top of the box. All of the related theory I have looked into says that moisture is more likely to rise like a cloud and gather near the top of the container. The greenhouse effect in a jar comes to mind. I have not done any testing myself but I don't have the means to do any great or formal testing. Would you be willing to test that?

[@VisionMiner]

Very nice! We always do the one you didn't test...... hot spool in the vacuum, hahaha! Great seeing the melted spools in there, too, lol! Keep up the great work!

[@wyqid]

I store all my filament in ziploc bags with silica. I leave the spool I am currently using on the printer until I am done with it. I do have a dehumidifier running in the room at all times, which collects about 10oz of water per day in central Florida. The room is climate controlled.

[@jaysonrees738]

It's surprising that many of these materials aren't stored in some manner of sealed cartridge. Sure, the cost would increase a little bit, but it would save an awful lot of trouble.

[@RedFathom]

you can also weigh the desiccant to determine its moisture content. i remember seeing a garage dryer that was hung from a spring and when it touched the floor it was full, and needed refreshing. probably need to make some cotton bags with weights written on them for the desiccant to make it easier to use.

[@razorpit]

So what is considered a humid environment in which you need to dry your filaments? Looking at my hygrometer my basement is currently at 48%. I store my filament in the box with the desiccant bag it came with, and I don’t reseal the bags. Sometimes I do leave rolls out, while I know that is not preferable, do I need to worry about drying my filaments considering my ambient humidity? I print with PLA, PET-G, and ABS.

[@Pitchlock8251]

I'm kinda surprised just how little time it takes for materials to hit their saturation point,

[@Eugensdiet]

Is that vacuum pump suitable for vacuum forming?

[@OldCurmudgeon3DP]

Mine only snaps once it's been exposed to PTFE tubing strangely. Never have an issue on exposed rolls, but it'll snap after a few days sitting in the printer. It's happened several times and always at the entrance to the reverse bowden on my direct drive. There's no appreciable stress at that location. On stored rolls the ends tend to break only where it's pulled through the spool to prevent unwrapping; likely stress related. The PTFE is supposed to be non-reactive but I wonder sometimes.

[@CNCKitchen]

That's creep under bending stress in the PTFE tube.

[@bumv2]

I had one roll, that did not like straightening. If I left it in the tube, then it snapped at like 5 places after a day or so.

[@tHaH4x0r]

I indeed had lots of trouble printing PETG, a lot of prints came out very weak and brittle. At the time I was very disappointed by this because I mostly switched over to PETG to make mechanical parts. However, after reading about this and having it in a descendant bag for some time, the print quality much improved and now prints 'proper' parts.

[@tochti]

Ich mache das ganze Mal auf deutsch :P Habe bisschen mit gefriertrocknung zu tun auf der Arbeit. Du musst die Spulen vorher erwärmen, bevor du das Vacuum ziehst. Wenn das Wasser verdapft, entzieht es gleichzeitig Wärme aus dem Material. Das Material wird kälter, und der Prozess wird gestoppt weil der Siedepunkt höher liegt als die aktuelle Temperatur im Filament. Alternativ könntest du ja den Pott auf eine Herdplatte stellen und ganz leicht erwärmen. Aus dem oben genannten Grund sind Gefriertrockner von innen auch immer beheizt während der Sublimation :D

[@geologist_luna]

You are doing a LOT of work. I hope you are retaining all the tests and results and you are going to write a couple of papers off these. It would be well worth it, and likely get your PhD (if you don't already) out of it. Great work.

[@TheJacklwilliams]

Stefan, I’m just beyond stoked that I came across your channel tonight. I’m building my FIRST 3D printer and I’ve been immersed in everything for some time. However, I was curious, months ago, re moisture. As a kid, I’m 55 now, I worked in injection molding and blow molding and I was very tuned into our dryer technology at the time and the role drying played in the process. This video was priceless. Thank you, so very much.

[@mhe0815]

Stefan, vielen Dank daß Du Dir diese Arbeit für uns machst!

[@olawlor]

Great video, Stefan! You might already have seen Joel's tour of Vision Miner earlier this year, where to get moisture out of fancy materials like PEEK or ULTEM they first re-spool onto anodized aluminum spools, then bake the filament at 150C, and finally drop the hot spool directly into a vacuum chamber, where it stays until it's ready to print: kzbin.info/www/bejne/d5Cup3dnrrCmapI

[@lauril1377]

Just lately ordered my first 3D printer and already your channel is my go-to spot for technical information about 3D printing. Keep up the good woork, as you yourself said "at least a bit scientific" content is much appreciated! :)