I’m relatively new to 3d printing, and I have a question about filament storage (mainly PLA). I purchased a bunch of different colors during the Black Friday sale, and have been regularly swapping filaments out on my AMS lite for various prints. Up until now, I’ve been putting the spools into reusable vacuum seal bags and pumping all the air out when I’ve swapped them out. This isn’t a huge amount of work, but the time does start adding up when I’m swapping colors out relatively often. What I’m wondering is, how important is it to store PLA filament in an airtight environment like this? If it matters, the realtive humidity of my house is anywhere from 30-40% depending on the day. Also, if it matters, I have an enclosure for my AMS lite that keeps the humidity of the filament I’m using around 20-25%.
It’s hard to give exact answers in that humidity range. My ambient humidity is around that range and I saw moisture issues start creeping in after a few months. I was storing in thick ziplock bags in plastic tubs and wasn’t drying the filament.
That’s another bit that matters - time - especially if your storage is a bit iffy and lets humidity in every now and then or lets it in slowly. Your storage sounds pretty good but if not drying, you may creep up eventually over the threshold if you don’t run through a spool fairly quick.
It gets worse - different colors behave a little differently, and to some extent what you are printing may show moisture effects more or less depending on how demanding. And it seems things like z-hop and retraction can compensate to an extent for some moisture issues.
Might be best to just see how it goes but keep an eye out for it. You don’t mention issues now so it could even stay that way. Unfortunately, filament can also arrive with significant moisture so you may get hit with issues on a fresh roll too.
There’s a great thread here on filament storage if you care to dive deeper.
It depends on the climate one lives in, the kind of models, and how meticulous one is about the quality of the print.
As a test, store a couple of rolls in the open and use/swap them as you normally would, and see what happens. If that doesn’t affect the print quality then you know you don’t have to vaccum seal them.
I used to store PLA on a shelf in the open, and never had any problems. Sometimes if a roll isn’t used for some months, I did notice the tip could become brittle, an indication that it absorbed too much moisture. But then after I cut off an inch or two from the end to get rid of the brittle tip, it could be used as usual without problems.
I now put PLA rolls inside plastic bags (not airtight seal) but that’s to prevent dust collecting on them. I have also stopped using desiccants inside the AMS (for X1C) when only PLA are in it.
So far I have never had to dry a single roll of PLA filaments, brand new or used.
This is the reading on one of my AMSs which is used for PLA only. It reads 4, at the bottom right of the screenshot. I don’t bother to find out what 4 means because it doesn’t cause any printing problem, but I think a value of 5 means it has become a fish tank 
Personally, I use mostly PLA or PLA Silk, and I don’t dry or vacuum anything. I don’t know if this affects it, but I get away with it.
Oh yeah. That is high. With humidity running like that, keep an eye on the desiccant in those pockets. It’s deliquescent and will dissolve in the water it collects.
It can absorb so much water that the liquid level overflows onto the electronics boards below the spools and kills them since the liquid is very corrosive.
A few people have reported that happening to them.
No desiccants in this PLA-only AMS. Yes, I was mindful of the risk of desiccant packets turning into gooey mess inside.