Long-term storage of plastic outside of the drybox will severely degrade the print quality produced by a spool. The plastic filament readily absorbs water from the environment. This increased moisture content will degrade print performance and may clog the print head.
If you need to remove the plastic from the provided drybox, please store it in another air-tight container. Markforged recommends the Pelican 1430 case.
Each spool of Onyx ships with two desiccant packs, while spools of nylon ship with one. A spool in the drybox should ONLY be stored with the desiccant pack(s) it shipped with. Any extra / leftover desiccant packs from previous spools of material will likely have absorbed moisture, which will permeate to the partial spool, making it wet.
Do not store partial spools of material in any type of sealable bag, as those do not protect spools from moisture. Air-tight containers used for partial spool storage must have solid walls.
If you plan on leaving your printer unused for an extended period of time, just keep the spool in the drybox with the filament loaded in the printer. The drybox and desiccant packs do a good job protecting from moisture, and drybox-stored material should last up to a year before the water content becomes too high for printing. When restarting a machine after a long idle period, run the Wet Plastic Purge Print utility until it stops steaming (which may take 2–3 runs).
Store all composite filaments at room temperature in a cool, dry place, out of direct sunlight. Kevlar® should be stored in a bag or container which blocks exposure to all light.