These bags appear to be airtight and can maintain that state, but they are not designed for filament. First of all it is difficult to fit a standard spool of filament in a bag, they just aren't big enough to easily do this as they are very narrow. More importantly, the valve is in the exact center of the bag, which aligns directly with the center of the thread - when you remove air, the valve sucks into the center. If the valve does not float freely in the middle, it will bend under the air pressure and will no longer be tight. The bags aren't big enough to fit the valve all the way to the side of the roll where they stay flat. In order for them to work, 1.) the valve must float freely in the center of the coil. Which is a bit tricky to get a vacuum but doable. 2.) You can't remove all the air, it's enough if the valve starts sucking in the middle. Alternatively, you can print a solid piece to fill in the middle of the spool so the valve sits flat on something, but that seems like a serious waste. Oh, and the color-changing desiccant appears to be in sealed bags, so I don't know the value of that.
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