Filament Drying Methods and Tools

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I try to find the answers by researching before I ask a question, and when I cannot find a specific answer, I turn to the community.

Here you are…the community… So I have questions.

One is “Do I have to dry my filament often?” By this I mean, if I dry my filament, say 4 PLA in the AMS 2 Pro for 6-8 hours, do I have to do it again in a few days if I don’t change the filament?

I have an H2S with an AMS 2 Pro, I also have a Creality Space Pi (single) dryer, neither does high temp, so that is on my list of things, or is it? And this is the question:

I was looking at the Bambu Labs pages on their filaments as well as their individual filament pages, and the drying recommendations look like this (temp and duration change based on type)

1. PETG HF must be dried before use to achieve optimal print quality.

Drying Condition:
Blast Drying Oven: 65 °C, 8h
X1 Series Heatbed: 75 - 85 °C, 12h

or, on the filament selection at the bottom of the shopping page, there might be something like this:

  1. Dry before use to ensure the best print quality and consistent finish. Drying conditions: In a blast drying oven: 50°C for 8 hours; In an AMS 2 Pro and AMS HT: 55°C, 8 hours; On an X1 printer’s heatbed: 60°C to 70°C for 12 hours. Store in a dry environment after use. For more details, please refer to: Filament drying instructions on WIKI.

Should I invest in a blast drying oven? Do the AMS 2 Pro and HT AMS provide the same style of drying? How often should I dry my filament? I am using several spools of off brand filament currently, and not happy with any of the prints on my H2S, and I am trying to figure this all out.

Thanks in advance for any advice or guidance.

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I’d invest in a good home dehydration unit for drying the filament properly. I’d also recommend you drying your filament if you’re going to keep your filament unused for longer periods of time. I’d suggest adding to your filament storage a reliable humidity measuring device and if it reads above 25% humidity, you better dry it before use.

Most filaments are naturally hygroscopic – some more than others. This means that, when there’s moisture in the air (humidity), filament naturally absorbs it. Though difficult to spot beforehand, hygroscopy is a factor that negatively affects 3D print quality.

Moisture within printing material can’t be seen, but when you heat it up in the hot end of your 3D printer, you can. Essentially, the water boils as the filament melts, and this causes bubbling.

Many of the materials used for 3D printing filament are somewhat hygroscopic. That said, how much and how quickly different materials absorb moisture varies. The following materials are most likely to get wet quickly: nylon, as well as other polyamides, PVA, TPU, PLA, ABS, PC, PETG, and usually most of the flexible materials. If interested into diving deeper into this topic, BCN3D has conducted research on the effects of humidity on 3D printing filaments and released a white paper detailing their findings. They looked primarily at the three most hygroscopic filaments in their portfolio, namely PA, PVA, and TPU. Of the three, PVA absorbed the most moisture during their experiments and TPU, the least. That being said, TPU fared the worst when it came to its resistance to poor storage conditions.

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Is there no point in a filament dryer then? Why do the recommendations speak of a blast drying oven?

What do you deem “longer periods of time”? A day? a week? a month?

Should I not leave things in my AMS for any period of time?

What do you consider “ a good home dehydration unit”?

I do appreciate the response, I just don’t think it answered several of my questions.

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Pretty sure BL uses the words “blast oven” to describe dryers such as the AMS 2 Pro.

https://wiki.bambulab.com/en/filament-acc/filament/dry-filament

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Is there no point in a filament dryer then? Why do the recommendations speak of a blast drying oven?

Depends on what it’s meant by “blast drying oven”, on what space you have available, on your budget and on how often is used, and on the amount of filament you need to dry. Personally, I’ve tried a few “drying ovens” and decided that for my personal type of filament storage and use, a (round) home dehydration unit, reaching up to 60 to 70°C, satisfies my needs…planned budget and available space.
It’s really up to you to decide what device serves best your purposes.

What do you deem “longer periods of time”? A day? a week? a month?

Again, it depends on the usual climate of your geographical location and the average temperature and humidity levels at your place. Hotter or dryer climate allow for a more “relaxed” approach for filament storage, while colder or more humid climates require a more “restrictive” drying approach (regular) for your stored filament.
As mentioned in my previous post, when storing filament (whether in the AMS or elsewhere) I always use a humidity measuring device to allow for monitoring the humidity levels of the stored filament. And as regular practice, I always dry my filaments for at least 8h prior to using them. That has avoided me lots of trouble with both the prints and with my printer.

Should I not leave things in my AMS for any period of time?
What do you consider “ a good home dehydration unit”?
I do appreciate the response, I just don’t think it answered several of my questions.

The AMS unit (no matter which version) is not sealed tight to stop your filament from absorbing humidity from the air, if kept in there for a week or more. I confess that in the early days, when I first got my X1C, I had the tendency to leave my filament in the AMS, thinking it’s “safe”. When using it after a while, I noted bubbling, and adherence issues, including low quality prints. I put a hygrometer inside the AMS and monitored it for a week (after drying the filament until it reached 21% humidity)… and after a week in the AMS, it got to almost 50% humidity (I do live in a continental type climate). From that day onwards, I’ve begun storing my filaments in monitored dry boxes, and always dry them up for 8-10 h or even more, before printing with them.

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While filaments need to be dry, repeated dryings (heatings) degrade the quality of the filament. I live in a rain forest where humidity can be a problem. I have had good results by storing my filaments in dry boxes - air tight containers with desiccant to absorb the air borne water. I also put desiccant packets in the AMS units to keep them dry. Desiccant beads can be recharged in the microwave in a few minutes. They also recharge nicely in the HT AMS set at 85 degrees, although it takes much longer. I use hygrometers to monitor for when the desiccant needs to be recharged. It takes about 3 days to rehabilitate a water saturated spool of filament in a dry box by way of equilibrium, providing there is enough desiccant to do the job.

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If you are printing in mostly PLA, then just as long as you store it well and don’t live somewhere with crazy humidity, drying shouldn’t be a huge issue. I’ve had my printer for a couple months, never dried my PLA and it still prints great. :person_shrugging:

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From my experience, you only have to dry it again when it had the chance to reabsorb moisture. If you you can prevent that, you never have to dry it again. For that, you just have to keep the environment dry enough. In my experience, the AMS is fairly tight. Add some containers with desiccant and you should be fine. You have to monitor humidity regularly and exchange the desiccant when it is saturated.
I have one PETG roll that has been sitting in an AMS for almost two years. when I used it last week, it printed absolutely fine. The filament that is not in an AMS, I store in those vacuum zip bags, together with a box filled with desiccant and a Bluetooth hygro-thermometer. Those bags are surprisingly permeable for humidity. The desiccant is saturated within 3-4 months. Those cereal boxes are certainly much better. I have very little space and the bags are more efficient in that regard.

I use molecular sieve as desiccant, but that is quite special. It can pull humidity really low to less than 1% RH. But it needs 250-300 °C to regenerate it so that you can use it again. That is quite a pita.

The classic is silica gel. I didn’t get below 15-20° RH in the AMS. For PETG, that should be good enough. I doubt that is sufficient for more hygroscopic material like PA or TPU. So you might have to resry them from time to time.

For monitoring humidity in my two AMS and all the bags, I have bought cheap Bluetooth hygro-thermometers BTH01 from AliExpress. they are 1,50-2€. I compared several and found those to be the best. In addition, I have a Bluetooth-Wifi bridge for 5€. That allows me to monitor all humidity values in the Tuya Smartlife app. Whenever any sensor exceeds 10% RH, I get a popup message on my smartphone, so I don’t have to regularly check humidity manually.
One of those sensors sits in every filament bag and in each AMS.

By the way, PLA is not very problematic. I don’t dry it at all and had no problems yet. But that certainly depends on the climate where you live. we typically have 40-55% RH at 22-28 °C during the year. If your home is more humid, you might have to manage humidity also for PLA.

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I was hoping this was the case, which is what I was really asking, and probably should have been more specific.

However, I did search the page for “blast” and there were zero instances of it found.

Is there anywhere that confirms this?

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Thank you, this helps a lot.

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Whatever you end up with, don’t be afraid to drill some holes in it if its not letting enough hot air out. A lot of the stuff out there kinda suffers from this because they design half for storage and half for drying. I can use a lot of other stuff to store, I can only use this to dry, it can get some holes drilled in it.

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No I don’t know of anywhere that confirms this, only that “blast oven” and “forced air” drying temps and time are listed as the same.