I had a bad PETG filament that the print was horrible. I reached out to Bambu Lab support and showed them, they immediately wrote back and said my PETG need drying out.
I got an electrical dryer and did as they advised, 3D printed again, and all is normal. Just my two cents worth.
yeah I have to agreeā¦ I live in New England, where we have summers at 90% humidity, and cold damp wintersā¦ Iāve had PETG sitting out for YEARS and just print with it and get pretty much perfect prints (even more so now that I have a Bambu printer)ā¦ yes, I have to dry my PLA, and my TPUā¦ but PETG really handles humidity well
While PETG is technically more hygroscopic than PLA, meaning it absorbs more moisture from the air, you can often print with slightly damp PETG because its molecular structure is more resilient to the effects of moisture compared to PLA, allowing it to tolerate a small amount of water without significantly impacting print quality; whereas even a small amount of moisture in PLA can lead to major issues like poor adhesion, warping, and nozzle clogging due to its more sensitive chemical composition.
Key points to remember:
- Moisture sensitivity varies within materials:
Although PETG is considered more hygroscopic overall, the way it interacts with moisture can differ depending on the specific formulation and manufacturing process.
- Impact on print quality:
While some moisture in PETG might not drastically affect the print, even a small amount of moisture in PLA can significantly degrade print quality due to its lower tolerance for water.
Sounds like you have made wise choices in filament brands.
Their experience with PETG in a humid environment seems to confirm the robustness of this material. PETGās ability to absorb moisture without significantly compromising print quality is a major advantage, especially in high humidity environments.
Here are a few additional points to consider:
- Composition: The composition of PETG can vary, which can also have an effect on moisture absorption and printing behaviour. What has already been mentioned.
- Print profiles: Even though PETG is less sensitive to moisture, an optimised print profile can improve the results even further.
- Storage: Although PETG is more robust, it is still advisable to store filaments in a dry place to ensure the longest possible shelf life.
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For reference (I didnāt notice it on this thread), Here are some of the TDS data on moisture absorption rate (higher is worse, and will absorb more moisture):
PC - 0.25%
PETG - 0.40%
PLA - 0.43%
ABS - 0.65%
PAHT CF - 0.88%
TPU - 1.04%
PA6 - 2.35%
So, its totally possible that in a relatively dry area, that some people printing PETG and PLA can get by without drying their filament, while others in a moist environment have to do it more often. However, as you get closer to that 1% absorption rate, things do get a little more problematic, even for those in dryer areas and especially for those in humid environments.
BTW, as mentioned before, the different rates of absorption are generally based on the chemical make up of the polymer, where some have more space for water to bind to the elements in it, and others have much fewer elements that have the space for water to bond to or get trapped.
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I do.
PETG HF straight from the shipping bag and into the AMS - doughy with lifting.
Same roll of PETG HF and same print after drying - flat/smooth with no lifting.
PLA print using spools from Bambu without drying and after drying.
For me drying makes a definite difference in print quality.
I suspect that pigments can also affect water absorption and printing issues and even the environment when the filament was extruded at the factory. Micrographs of filaments are kind of nasty with all sorts of pitting and surface roughness so it gets reasonable to question if manufacturing variables could increase or decrease that. Bet it does. And changes in surface area will likely directly affect water adsorption since itās governed by surface qualities.
Filament makers want to extrude and spool the maximum amount of filament they can. Just like how we see changes based on extruder and chamber temps, Iād bet (but have no data to back it up) that melt temperature and room temperature/humidity both matter along with any number of other parameters including how the plastic used to make filament was stored and handled before being extruded.
I tend to believe thereās a lot more variability between spools than the spooling uniformity and pristine shipping boxes would imply. And then thereās all the end user storage and printing variables on top of that.
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PAHT-CF could not be printed practically fresh from vacuum sealing with perfect or even good results. Prints were simply not usable. Totally rough surface, no fit. Drying time 24 hours at 70Ā°C. After that it was perfect.
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Drying filament that is already dry is indeed a waste or energy (and time).
I have had 1kg rolls of eSun PETG straight out of the bag lose 2g in weight after drying.
Good points all around, I think!! Not surprisingly, it seems to vary based on location and environment. Unless I missed it, did anyone mention keeping it stored in a foil bag with silica, or in the AMS with the silica packs? It sounds like the most common storage method is to just leave it on a shelf somewhere, open to the air/environment. So, I would have to think that storing it in a container or pouch with a silica gel pack would help. Iām interested in PETG, because I just started a new job, and the only spot for the printer is in a smaller room. When we print with ABS, it absolutely STINKS, so Iām looking for alternative materials. Thanks!!
Take a look a this thread: What do you find best suits your filament storage needs?
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I thought Iād add my experience. I picked up a spool of Bambu Basic PETG and landed here while searching to find out if I need to dry it (and how). Bambu says drying is ārequiredā for PETG on the A1. Never printed PETG before so I thought Iād try with and without drying to see the difference for myself. Printed a baseline without drying and it looks perfect! So much so that I didnāt even bother with the drying test. Iāve printed a ton of stuff with it now with no drying and out of the bag for about a week. I live in a very rainy place with a pretty consistent ~50% RH in my house.
I see the before and after picks some have posted and the big differences drying makes for some. Maybe I just got lucky with this spool but, based on my experience, Iād have to recommend not assuming you always have to dry PETG. Try a test print and see. Might save you some time and energy.
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You may want to specify if you used a generic PETG or Bambu PETG-HF. Bambu no longer includes āregularā PETG in their filament guide because they no longer sell it. When they did, drying was considered optional. They only required drying when they introduced PETG-HF.
I dry ALL my filament before use, at least long enough to see if it is losing any weight. I recently tried some cheap (5 spools, <$10/spool) Jayo PETG. It is the only filament Iāve ever bought that has lost less than a gram of weight, even after 12 hours of drying.