Confusion re: drying/humidity

Bambu Filament and Accesories Filament
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So I’m looking to pickup an A1 Combo and variety of filament as an entry to printing with my kids, but one aspect still has me confused – drying/humidity. While I see filament like PLA Basic doesn’t require drying, others I’m hoping to try (like PETG HF or TPU) do.

So OK, I can pick up a dryer, follow recommended temps/times, store things in sealed containers with desiccant, etc. But when it comes to actual printing after drying, are print times short enough that it can just be loaded on the AMS Lite and run? (Humidity at home is generally 30-40%)

I see some people feeding directly from dryers and other controlled enclosures. While I imagine that’s “ideal”, is it basically necessary for good output with materials that require drying? I’m hoping/assuming not since Bambu doesn’t seem to offer any options for the AMS Lite. Wishful thinking?

Sorry for the basic question, but time is running out and Googling hasn’t helped much outside of initial drying and storage.

Thanks!

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Don’t stress over it. You don’t have to buy a filament dryer now. I have been printing for more than 2 years and still don’t own one. You will start with PLA which is the least hygroscopic. As someone totally new, keep things simple and just enjoy the experience.

There will be a time later when you may notice that you need to dry some filaments. But if you are mainly doing PLA and PETG, you may or may not need to, depending on your climate and the type of models you print.

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You will find that just PLA goes a very long way, especially for a beginner.
Master PLA, then move on IF you have a need and purpose for other materials.
Over time your knowledge and confidence levels will rise and THEN trying new things comes with far fewer headaches.
Like how to deal with the problem of printing certain filaments without and enclosure…
PETG can work in an open printer but ABS or Nylon will give you a lot of frustration…
TPU might work too but it is best to have an enclosure for more complicated filament types.

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Back in the day I never bothered to dry PLA. If it sits in a humid environment for months, unused, you may need to dry it… but if you are moving through your filament regularly, you shouldn’t have too much issue.

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Thanks everyone. Overthinking complete, time to pull the trigger. :grin:

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Welcome to the community!!!

Listen to this member’s advice. It is far too often we see folks overanalyze the subject of moisture. Don’t get me wrong, hydroscopic filaments like PETG and PC can ruin a print but these are not very likely that you’ll be using them with an A1 anyway given that they like higher temperatures that will require either a chamber or some kind of cover for the printer environment to stay warm.

But if you are curious and wish to explore the benefits of drying filaments, here are some zero-cost ways of doing it.

Note: I own a dryer so these methods are the one’s I used before investing in a dryer. The only reason I use a dryer isn’t because it’s more effective, it’s just more convenient and easier.

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The BOX!!!

If you have an A1, not the A1 Mini, did you know you already own a drier? Just use this approach.

Take your filament box, cut the top off. Place the filament on your bed, cover the filament and set the bed temp to 50C and wait 4-6 hours. It works. Inspired by this YouTube video [Click Here] Ignore the fancy fan and hygrometer/thermometer, those were just curiosity (https://www.youtube.com/watch?v=WC3jvuq-uq8)

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Also of note. Certain PLA filaments like Silk and Matte can benefit from drying. Guess, which one of these Bambu Silk test samples was wet straight out of the box?

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Your kitchen oven

Yes, believe it or not, you can use your kitchen oven at 130F or 50C.(some ovens have a “warm” feature which may not be hot enough)

Don’t use a toaster oven as it will not keep even temps and you could end up with one of these trophies. :laughing:

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DO NOT USE YOUR MICROWAVE!!!

Aside from the fact that it won’t work, you are more likely to cause a fire.

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Weigh it!!!

The biggest mistake I see posted here is from folks who say, “I dried it thoroughly for X hours.” To which I quickly ask, “How did you know it was wet in the first place?”

The point is, many people waste hours chasing the wrong problem. As the photo above of the so-called no-need-to-dry Bambu Silk shows, moisture can exist even in factory-sealed filament and can ruin a print. However, before you go down that rabbit hole, ensure the filament actually has moisture and that it’s been properly removed. How? Simply weigh it on a $10 kitchen scale before and after drying. During the drying process, weigh it periodically. When it stops losing weight, you can be fairly confident that most of the moisture is gone.

An example of the scale I use… don’t tell my wife…:stuck_out_tongue_winking_eye: she’s been looking for where this scale went so I bought her another $10 scale for her baking needs.

Click here for $10 scale

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@Olias thanks for tips! We have a pretty high-end double oven set and a couple digital kitchen scales, so I think the path is set for now. :slight_smile:

I also came across this project which seems like a fun addition to help keep them dry… someday. :wink:

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There is no need to overanalyze moisture. You might familiarize yourself with what moisture problems look like so you can recognize them if they start creeping in, though.

The thing is that not everyone has moisture issues. But many also do. Look through the posts here where people are asking for help with print issues and the causes tend to be dirty build plates or moisture for the majority of them.

Also, beware of advice from anyone who tells you right off that you do or don’t need to dry. They may or may not need to dry - that’s their experience. Your experience can also be that you do or don’t. But they can’t tell you in advance how your experience will be because they aren’t considering your local environment.

Like I said, read through some of the print issue posts and familiarize yourself a bit. You may or may not have water issues. Also be aware that water issues can grow in over time. That was my experience. I started with PLA and it printed great without drying until it didn’t. It was because in my environment there was just enough humidity that it took a few months to make my filament start acting up as it absorbed water. With PETG HF, prints using it right after taking it from the bag showed water issues for me. Drying it fixed them. Some filament can also be “wet” enough straight from the manufacturer to show moisture issues.

Ambient humidity is the big factor in both how effective drying can be and also in how long (if ever) before filaments start acting up.

And on weighing. Weigh any spool and tell me how much water is in it. You can’t. Weigh it again after “drying” and tell me how much water is in it. You still can’t.

All weighing before and after tells you is how much water was lost. If it’s not much, was the spool dry to start with and not much water was even able to be lost, or was the drying ineffective? No way to know by weight. If the difference is a lot, then it’s likely your drying was effective but it may still not be “dry”.

There are other ways to tell but it will attract all sorts of comments that will pollute your thread. If you want to know, just PM.

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Just keep in mind that you don’t want to go much over 50c for PLA or it will start to slump and distort - even imperceptibly, and will mess up your prints. 60c is an absolute max.

50c = 122f
60c = 140f

Many ovens (in the U.S.) that don’t have a super-low warm setting start at a minimum of 170f, which is 76.6C - this will absolutely melt your PLA filament.

Some toaster-style air fryers have a food dehydrator mode that allows for low temperatures. If you go this route, I would take some measurements near the fan outlets inside while running just to make sure it isn’t using extra-hot air, especially during preheat. even a small jet of extra-hot air hitting the filament will melt it - even if the overall chamber temp is correct.

This is advice from a man who has melted spools in years past. I can introduce you to him sometime… :wink:

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Yes, and no. You are right that two measurements won’t do it, but a set of measurements over time can tell you exactly how much water is in the filament.

You can use calculus (or a visual graph) to actually figure out if the filament is nearly dry based on the weight curve becoming asymptotic to a line. I am not suggesting you do this, but you can.

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That’s actually incorrect. It can asymptotically approach a value but all that tells you is the weight isn’t changing. It’s no different than just cooking the filament for the same amount of time and taking your second measurement then. To be technically correct, all that the weight not changing anymore means is the filament is as dry as you can get it under those conditions, but it doesn’t mean the filament is “dry”. It may be, but it also may not.

If the air in the filament dryer is 0% RH, then the weight you will asymptotically approach will be to that of a totally dry spool. But depending on the humidity in the dryer, what you will asymptotically approach is the filament weight with whatever moisture the filament contains at that humidity and temperature. As the ambient humidity level rises, it will be higher and higher moisture contents that you approach. If people don’t account for that they can swear their filament is dry even though it may not be.

It’s apparently pretty counterintuitive because you are absolutely not alone in how you’re thinking about it.

But for most people’s purposes, all that matters is you have filament that is dry enough. If OP or anyone isn’t seeing moisture issues they are doing well. But issues can also can creep in over time from filament just gradually absorbing water out of the air.

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Of course. Instead of “dry” I should have said “maximum relative dryness.” In the real world, you can only get as dry as the RH around allows vis-a-vis the specific compound you are dealing with and the atmospheric pressure.

That said, in 70-90c w/ RH ~10% everything I use gets “dry.” And by that I mean, no hydroscopic effects - stringing, voids, crackling, inconsistent extrusion, etc… Back in 2014 I was printing with a TAZ, and drying was barely a thing. When/if my filaments did get wet, I’d chuck them in the oven on looooow. Then, print in a dehumidified chamber.

It is also possible to over-dry filament. This is not widely known. Most plastics get some of their shock-resistance and flexibility due to their water content. When plastic is too dry, it cracks, and doesn’t flow properly.

I guess what I’m saying is that getting most filaments to vacuum-level dryness is not needed, and not always helpful.

I understand that your experience with the issue has been different, and that’s ok too.

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PLA, PETG and even TPU can usually be printed for a while after drying. Depending on climate of course.

Living in Marshland, I try to always dry my filament before putting it in the AMS. PLA is not redried while in there (@<10%), except that one old and troublesome trnasparent roll that needs weekly drying before becoming too brittle for the AMS.
PETG only if I see curling. But it can easily sit in the AMS for a month without a dryer.
With TPU, I see increased stringing and curling after about 4-5 days on the rear spool (22-24°C, 30-40%).

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We are in agreement then. But this is a significant thing for those who don’t have low ambient humidity. Your relative humidity apparently lets you dry to plenty of dryness. But for those starting at higher ambient humidity, they won’t reach the same level of dryness you do when their weights stop changing.

I’m not advocating vacuum level dryness, either. I purge my dryer with approximately 2% RH air - before it gets heated - but I don’t even let it run until weight stops changing. I used weight change and RH in the drying chamber to see what was better - for my purposes - and RH is a minimal effort measurement that tells me what I need to know.

But my results can’t really be directly compared with many dryers because I do that purge - except for results after drying. If I close my dried spools up in a sealed container with a hygrometer and let it cool, the RH pulls down below 10% pretty quickly as the filament soaks up water in the container. If you or anyone do the experiment themselves, I’d be really curious how it goes.

My experience really hasn’t been different. Printing for me started out great then water effects started showing up. I also tried printing PETG HF straight from the bag and had water issues. There are hundreds of posts here where prints used to be fine but then stopped being fine. Or prints were bad right out of the gate.

What was different about my experience was I dug deeper than the lore and ran a bunch of experiments to suss out drying filament because the Sunlu S2 I had bought wasn’t cutting it. I tried various approaches - following the directions, purging with ambient air, and propping the door open, and saw that with the ambient humidity we were having, filament was only drying somewhat.

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This method may not be accurate: https://youtu.be/5CFxT1q6dX8

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The method is sound, but as the guy says, the cheap scale used in his video is not accurate.

We have the same model, used only to portion out cat food. I used a better scale to actually “calibrate” four food dishes so that each is 113.8g. On the cheap scale, they start out weighing 113.7 to 14.0g. Then the readings start to drift up or down after about thirty seconds; let it sit for a minute or two and 50g becomes 52g, or 48g, depending on the mood of the scale, and it keeps drifting the longer you let it sit.

His method made the lack of accuracy and precision more acute because the short ~5m lengths of filament could only absorb small amounts of moisture, beyond the capability of the scale to detect. That whole test is useless - it should have been omitted, or repeated with a much better scale. I only see problems when moisture weight gain of a nearly full spool (300-400m) exceeds three grams.

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Dude!!! Let’s put this into perspective—it’s not like we’re researching cancer here. This is 3D printing, and ±5g is more than accurate enough. That is, unless you’re Thomas Sanladerer from the video you posted. But hey, he gets a pass because, well, he’s German. Precision is practically in his DNA—five 9s and all. :joy:

Jokes aside, don’t fall into the trap of overthinking this stuff. Speaking as someone whose upbringing straddled both German and American cultures—and who often rails against the Chinese corner-cutting philosophy of chabuduo (a term I learned from Sanladerer, by the way)—I can tell you this isn’t worth overthinking. While I enjoy Sanladerer’s content and think he makes great videos, this one wasn’t one of them. It leaned more toward “Chicken Littleism” or clickbait than actual practicality.

The takeaway here isn’t that you need NIST-level precision when measuring moisture weight. It’s simply that you weigh it rather than guess. Don’t get hung up on irrelevant details that won’t make a difference; focus on the goal: determining moisture presence, not achieving 64-bit precision on the weight. Any scale, even a 12th-century BCE Mesopotamian balance :balance_scale:using beach sand, is good enough for our purposes.

To paraphrase favorite quote relating to this kind of topic from Ghandi; Whatever you do will be insignificant, but it is very important that you do it. :wink: