How long do you have filament sitting “in the open”? I mostly print with a single filament roll at a time, and just leave it on the printer. A 1kg roll lasts me several weeks. For long time storage I keep it in an air tight box with disiccant pouches.
But how long can I let it sit before I should start storing it with disiccant and/or drying the filament before use?
I’ve literally never had my filament not just sitting on the spool on my printer, which is just kept on my desk in my living room. Never had any problems with it.
Everybody is storing it in different conditions. Me for example, my printer is in front of a window that gets afternoon sun.
No cover, no curtains or anything. I just leave my PETG roll on the printer and print whenever I want to. Just recently after like 6 months of not printing I printed something to test without any problems at all…
How long depends on your humidity. If you live somewhere with high humidity, PLA or PETG filament can go bad in a couple of weeks or less. In a dry location, maybe never for PLA. Nylon will go bad anywhere in a matter of hours. It’s not easy to tell if filament is wet - weighing filament can tell you about the moisture gain/loss, but of course doesn’t work when you are actively consuming it. When filament gets wet, prints start to get bad in various vague ways that can seem like printer tuning issues. Sometimes it’s bad bed adhesion, sometimes poor first layer quality, stringing, or bad overall print quality.
If you want a good storage solution you need an airtight box. I use Iris Weathertight storage boxes with 1lb desiccant canisters and a humidity monitor. The 62qt box can fit 16 spools and room for the desiccant.
I just got a cheap food dehydrator and stop thinking about it. I just print as needed, mostly functional stuff, or just enclosure for my electronic projects. 1 kg lasted me months, I’m still on the same kg that I bought early this year. And I’m in SEA, we have like 90+% humidity here.
I store my open but not currently used rolls of filament in a large plastic tote with a gasketed lid. I guess you could call this a “dry box,” but it’s not very heavy duty. I have a stocking full of silica gel desiccant beads in it, the kind that change color when they’re allegedly saturated. I nuke that in the microwave about once every six months. They’re never indicating their saturated color by then, but it pays to be sure.
Whatever roll is currently loaded in the printer I have in a heated filament dryer which can output right to the printer. Its lid is not sealed, per se, but it’s not just open to the air, either. I run the dryer when I’m printing. That hasn’t given me any issues.
In my environment – a basement that’s not terribly damp, and I leave a dehumidifier running maintaining an alleged 30% RH – if I leave an exposed roll of PLA on the machine it will get brittle enough to potentially start snapping bits off within about 2-3 weeks of sitting exposed to open air.
