What's the problem with moisture?
Almost every treatise I read about 3D printing, especially for novices (novi?) contains dire warnings about keeping your filament dry. Filament comes in practically hermetically sealed bags with packets of desiccant, "drying box" designs abound, and yet, I have never had a printing issue that I can attribute to the filament having too high a moisture content. But maybe I just don't recognize what effect moisture has on the process. Has anyone else had issues known to have been caused by "damp" filament? Can you post pictures of prints that have documented defects due to moisture so we can recognize the issue and take steps to avoid it?
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RE: What's the problem with moisture?
I haven't experienced it myself, but I think moisture creates little bubbles in your filament that pop when extruded, leaving lots of tiny gaps in your print.
RE: What's the problem with moisture?
@matteo-cristini
Are you speaking of audible "pops"? Given the volume of the typical melting chamber and flow rates, it seems unlikely to me that any residual moisture in or on the filament would not have "boiled" off long before the bead ever left the nozzle opening to make its way into the print. Is something else going on?
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RE: What's the problem with moisture?
@reddawg
This is what I've heard from others - as I said I've never had problems with moisture myself, nor experienced any "popping" filament.
RE: What's the problem with moisture?
The effects of moisture depend on filament. Print with nylon and you will see it immediately, as soon as you open the bag that stuff starts sucking it up.
For the common types, especially petg, moisture results in increased stringing. When it has absorbed a lot it does produce pops as its printed. The thermal transition zone is actually quite small and you must remember that the nozzle area of your extruder is sealed so the only way that boiled water/steam is getting out is out of the nozzle. If it wasn't sealed you would have leaky plastic coming out the heat block. That statement is not anecdotal, I had some petg that was very old and gave it a go anyway.
RE: What's the problem with moisture?
Rather than a lengthy discussion, here are some examples I've encountered.
The 1st pic shows an issue I ran into printing PETG. Everything had been printing nicely until I noticed the finish issues in the bottom print. The top print shows the identical gcode printed after drying the filament:
Here's a more recent example with PLA. I had been printing large full-bed 24 hour+ prints in Paramount PLA with no issues during dry winter days:
We experienced a sudden change in weather with greatly increased humidity and stringing with the same PLA went insane:
Upon completion of a print or two, I dried the filament and stringing was reduced to normal:
There are no hard fast rules for when moisture will become a problem. Different manufacturers and filament types will behave differently. Experience printing in New England will vary from those printing in Phoenix. It's one of those problems that will pop up unexpectedly, and you'll be best off mitigating it (e.g. bagging filament with desiccant packets) and being prepared to fix it (e.g. having a dehydrator on hand) when and if needed.
RE: What's the problem with moisture?
Rather than a lengthy discussion, here are some examples I've encountered.
The 1st pic shows an issue I ran into printing PETG. Everything had been printing nicely until I noticed the finish issues in the bottom print. The top print shows the identical gcode printed after drying the filament:
Here's a more recent example with PLA. I had been printing large full-bed 24 hour+ prints in Paramount PLA with no issues during dry winter days:
We experienced a sudden change in weather with greatly increased humidity and stringing with the same PLA went insane:
Upon completion of a print or two, I dried the filament and stringing was reduced to normal:
There are no hard fast rules for when moisture will become a problem. Different manufacturers and filament types will behave differently. Experience printing in New England will vary from those printing in Phoenix. It's one of those problems that will pop up unexpectedly, and you'll be best off mitigating it (e.g. bagging filament with desiccant packets) and being prepared to fix it (e.g. having a dehydrator on hand) when and if needed.
When it has absorbed a lot it does produce pops as its printed. The thermal transition zone is actually quite small and you must remember that the nozzle area of your extruder is sealed so the only way that boiled water/steam is getting out is out of the nozzle. If it wasn't sealed you would have leaky plastic coming out the heat block.
RE: What's the problem with moisture?
I have a dry box for TPU and I try to keep it under 20% humidity. For all my other filaments I will bake them at about 180F for an hour if I have not used them in a long time.