Drying PETG is a waste of energy! (for me)

Bambu Lab X1 Series
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I know - the title is deliberately provocative in order to attract as many opinions as possible.

For some time now, I have observed the following in many threads in which someone describes a problem when printing with PETG: One of the first responses is often, “You need to dry your filament first, even if it’s new.”
I can’t understand this answer at all - unless it’s about the finishing touches. Let me explain:
I’ve been printing for about 5 years now, 95% PETG (but also some PLA, TPU and ASA), about 100kg so far. I have had many different printers, at the moment a CR-10, a home-made Voron 0.2 and a Bambu X1C. My printers are in the basement, which is only slightly heated, at about 16°C in Hamburg, northern Germany - over the whole year we have an average humidity of about 78% here. Here is a link to the source, so you can compare. I keep all my filament rolls open on a shelf.

And I have never dried a single roll of filament.

To check this again, I took a no-name PETG from my shelf that has been sitting there open since the beginning of the covid-19 era, i.e. for about 3.5 years. I printed a benchy - flawless. Dried for 12 hours - 0.6% weight loss.
I put half the roll in water and let it soak there for 4 days - when printing the Benchy there was a little stringing on the cab - but only 1-2 small threads. The differences can only be seen in good light. Then I dried the filament again for 12 hours: 1.1% weight loss.

For reference, here is the benchy of the absolutely dry filament and the “dipped” one. Both printed with “General PETG / 0.12mm Standard” - no other settings altered, no calibrations made:

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To summarize:
For me, drying PETG is pointless unless you value the last ounce of surface quality in a print.

But since there are many makers out there who see it quite differently, I ask myself: What could be the reason for these different experiences?
The climatic conditions? They are actually rather disadvantageous for me.
The filament brands? I use 80% “extrudr”, but also “goedis”, “amazon basic”, “sunlu”, “filamentworld”. No problem with any of them.

I don’t get it - do any of you have real before/after pictures of prints that got better after drying - without changing anything else?

I’m happy to hear about experiences and opinions - backed up by facts if you like.

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I have seen the effects of water in various filaments over the years. Ok, saying that, it is possible that the water content could have come from the manufacture through water cooling with the addition of the filament not being immediately packed.

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I never had to dry PETG either until I started using 1.2 and 1.8mm nozzles on my Voron to print it. Once you get to that extrusion diameter you have to dry it every day or two or else it comes out looking foamy.

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I totally agree with what you’ve written.
I assumed the reason I never had issues printing PETG was because where I live in Australia our climate is fairly consistent and relatively low in humidity.
I look at some of my old prints done with my Mk3s’ and they still produced better looking prints than what I can get with my P1P/S, especially on corners, overhangs and top layers. But they are much slower and require more fine tuning.
I don’t rate the Bambu Lab basic PETG. I’ve used lots of cheap brands and they all seem to produce better results, which is disappointing as it’s quite a bit more expensive here, unless you buy in bulk with the member discount but that only makes it equal in price.

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There are various blends of PETG.
For example:
Verbatim PETG is supposedly hygrophobic and I never felt the need to dry it, nor could I tell the difference after drying.
Fillamentum PETG is fine without drying, but there’s a difference if you dry it first.
Spectrum Matt PETG is unusable when left out of dry box for a few hours. Strings and blobs galore.
Most other brands print without drying and you end up with an ok print, but it still makes a difference if you dry your filament.

Btw it is winter here now and ambient humidity where my filaments are stored is about 25%, in summer it is over 55%. That also makes a huge difference.

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From my experience: drying PETG before use can make a HUGE diffrence :smiley:

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I never dried PETG either. But I have an old batch 5-6 years old. Under normal printing conditions it is mostly fine. But when I need stronger prints, raising the temperature causes pops, destroying surface quality completely. On the plus side pops actually improve the layer adhesion by forcing material into existing layer.

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Yeah I put this exact sentiment on Reddit all the time. It’s like the dumbest thing I can think of. I’m sure that it being slightly too moist can exacerbate problems that lead to clogging, but ultimately it’s always something else that’s the core issue. Every time I see it someone on Reddit say that that’s what they would do I’m like… I don’t believe them.

It’s like that’s there’s no way that you just baked your filament or dried it in some absurdly overpriced little dehumidifier that doesn’t work and then that fixed the extremely weird patterning on the walls of your print.

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Relative humidity takes into account the air temperature. Air with a higher temperature has a greater capacity to store water. I checked my city (Houston) on the site you referenced and the information wasn’t accurate.
Someone storing their filament in their garage at 35C and 70% RH would have their filament exposed to much more moisture than someone storing it in their basement at 15C and 70% RH.
I have personally seen water boil off to steam when wet filament was extruding. Drying can make a difference for some people in certain conditions.

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I’ve been printing PETG since 2014 and never dried anything until about a year ago. I live in a dry climate and was happy with my results. Only after getting lots of comments on my videos telling me to dry my filament did i buy a dryer and try it. My intention was to prove that it made no difference, but to my surprise, the improvement was significant. The biggest difference was reduced ooze during non-printing moves.

I now dry everything–even right out of the package–because it saves so much trouble and lets me focus on other things.

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Fighting moisture - drying filament and keeping it dry, is total pain in the butt. It requires money for electricity, drying equipment, airtight storage, and desiccant. It requires time I’d rather spend on anything else.

But I do it, because it works for me. Drying filament has corrected problems with plate adhesion, layer adhesion, stringing, stray blobs and holes, and helps provide a consistent finish. So I dry my filament and work to keep it dry because it is easier, cheaper, and quicker than reprinting failed prints. When a print does fail, I have one less variable to consider.

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I tend to get your weather 1h earlier :crazy_face:

I never needed to dry my filament… until I got the X1C. In particular with Bambu PETG, drying is a make-or-break difference for me.
Even with some old, soaked PLA or in particular Glow-PLA since really brittle stuff already breaks on its way from the AMS to the printer.

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I’m pretty new to 3d printing, but see filament drying as a necessity based on the conditions where I reside. I am located in the Pacific Northwest of the U.S., situated between the Olympic mountain range to the west, and the Cascade mountain range to the east. We get a LOT of rain here, so the humidity is usually fairly high. Right now, the outside temperature is 10.4C with 84% RH. My ‘print room’ is currently at 17.6C and 53% RH. General concensus points to an acceptable RH of 30% to 50% for common filaments. No issues so far, but I have only printed PLA which is touted as more forgiving to moisture absorption. It’s really not a problem to vacuum seal opened filament with some dessicant thrown in. An ounce of prevention is worth a pound of cure!

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Thanks for posting this absolutely pointless thread. You wasted all that time typing all those words and you just come off as incredibly ignorant. Nice work. :clown_face:

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For the points in the pointless discussion…

Haben fertig… :partying_face::grin:

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Yep, I think you accomplished that item quite well. :joy:

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Been printing for 5+ years, did not get consistent quality until I started drying material religiously in an actual good dryer. Lots of drying methods out there that could lead you to believe all the water and humidity has been sucked out, but then you try an actual good dryer and it makes an improvement. I use the Eibos Cyclopse and Sunlu S4. Just about all the little ones are hit and miss.

For me though, I know it’s wet with the solid flat layers, not the walls. If your surfaces are nice but you still have wall surface and stringing issues then yes that’s another problem more than likely.

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It only seems dumb if you don’t know what you are talking about or haven’t experienced it. Filament printing badly when wet is very well understood and can cause lots of issues other than clogging, like underextrusion or just messing up the quality of the print due to the expansion of steam bubbles and it can cause a lot more stringing.

Filament that is too wet can cause weird patterns and textures on prints, that is due to the expansion of steam within the plastic, you can hear it popping as it extrudes.

What makes you think that filament dryers or food dehydrators don’t work? They absolutely do, just because you can’t believe it doesn’t mean it isn’t true. The very fact that the weight of the spool reduces proves that the dehydrators do work, but sure you who has probably never used one says they don’t work so you must be right.

I have used filament that has gotten too wet, including nylon, PETG and PLA and have had issues in prints due to them being too wet, significant issues, drying them in a filament dryer or food dehydrator removed the issues, so what other conclusion is there when nothing else has changed than that the moisture caused the issues and that the drying removed it?

It is very well known that plastics tend to be hydroscopic and that it effects print quality but of course you know better even though you can’t believe that filament dryers work.

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Hi all!

Thanks for all your insights!

Good point - never printed with anything other than 0.4 and 0.6 nozzles. Although I think 1.2 and 1.8 are rather niche applications, and that majority of people drying their filaments don’t print with big nozzle sizes either.

Good point! Maybe I don’t have any issues with moisture because I mostly use the same PETG brand and type. Anybody else having brand-specific experiences?

I would tell it this way: “Dry your filament” would not be my first advice for 99% of the pictures of failed prints I see here. Most of the time it’s too much/less cooling, no adhesion due to fingerprints/bed too cold/flow too low, temperatures or speeds… classics. If a print doesn’t look nice, I would consider drying. If it fails, there must be at least another problem - in my experience.

True and a good point. The question is: Do all people that have problems with wet PETG live in areas that have rather 35°C and 70%RH ? Serious question. And wouldn’t dumping the filament in water at least simulate those conditions?

Thanks!

While I can totally understand that point (in the end all that counts is the well-finished print, isn’t it?), it is not my way of doing things. I have to know why things worked or did not work. If I can’t reproduce an error consistently, then I haven’t understood why it failed the first time!

Thanks for the data!

Sorry? I did not intend to be ignorant, that’s why I posted this thread to better understand other opinions. EDIT: Uh, missed that you registered extra to write this. Welcome in the board, and have a nice time.

Thanks - could you give a hint where you live and which brands you use?

Did you weigh your filaments before an after? Could you be so kind to share your data?
I would like to compare the values to the ones I stated in the opening post. (0,6% and 1,1% weight loss for 3yo open filament and watered filament). Would be great to work out a rough estimate of PETG humidity where problems start.

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Good night & happy printing!

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Do you have a tip for a site to compare humidity worldwide?