That is actually possible. I’ve seen it and so has @NeverDie. If you have a good scale you can try weighing before and after drying and if you are actually humidifying your filament a scale will see that.
I’m glad you ran that test. The Ikea 365 series looks like it seals well so if the spool was pretty full that should give a good idea where you are and 6 hours to 26% is actually looking promising.
I will be curious how far it drops overnight. I usually drop a couple more percent overnight. It’s not a particularly fast measurement.
Unfortunately 26%, or even 24% if it keeps dropping, puts you square in the “I don’t know” range. I don’t have much of a track record to go by but with PETG HF, my spools have been arriving with RH numbers in this test in the 40-42% range. This is what a print looked like printing straight from the bag:
You can see a little lifting and doughy-looking surface but not terrible. After it was dried, the hygrometer test went below what the hygrometer could read and prints were beautiful.
But this hygrometer test may not be so transferable between different types of filament even though yours is also PETG. The humidity in the box will be affected by how much the water likes sticking to/in the filament. It’s an indirect measure of humidity and you and I are the only ones I know of who have done this test so far. I’d guess that even with the different manufacturers, PETG versions would be more similar than different so at this point there’s nothing glaring and still a mystery. Your prints don’t look terrible. If it is water, you’re on the edge like I was before drying.
My dryer is also an S2. Stock, it doesn’t perform that great if you have much background humidity. Starting at 47% in the Ikea sounds like you’re where we were a month ago. Filament drying will be impacted with that kind of humidity. The more hygroscopic the filament the less successful drying with ambient air will be. I forget if I said here too but just think how your clothes feel on a humid day if you’ve been sweating vs how they feel on a dry day.
The simple fix is always dry on dry days. There’s a thread I started here on my filament drying adventures and it got long and at first there were concept errors and such but if you go through you’ll see what I was getting at. https://forum.bambulab.com/t/filament-drying-preliminary-results
Again, don’t know that you’re seeing water effects. Not familiar with that filament. What I do know is manufacturers say you want it dry. Even though yours is actually what I would think is pretty good (but not as good as it could be) depending on how much they stress “dry”, this next bit may be of interest - or not.
To get dry air, just use a low flow pump like an aquarium pump to push room air through a desiccant column and feed that into your dryer. It sweeps the moist air out while letting the filament see dryer and dry air. You can easily cobble together something serviceable with just an aquarium pump and a container of silica gel beads. It helps if the beads are indicating but they don’t have to for just a test. The pump I used was $20 at Amazon, and 500g of beads will last you a while. I dried 26 spools (and stopped early because I ran out of spools but it was almost done anyway) on 800g so 500 may even be overkill. What you want is path length. Stab a straw of some kind to admit pump air into the bottom and collect air at the top and plumb into the S2. Dry like that and your filament will pull that Ikea hygrometer to 10% or lower. And if you do it, put some cotton or some kind of bead filter into the straw or other tubing. In the dry air the beads pick up static charge and will literally jump around and into the tubing and stick from static charge.
But I really can’t say on your filament moisture content, unfortunately. I was hoping you’d see numbers like I saw undried. That would be easy. You’re in a kind of gray area where I just don’t know.
What I do know is this is what that same print looks like with dry filament. It’s perfect. But until we get more results I’m hesitant to tell you to set up dry air but that will answer the question. If you do the dry air thing and that fixes you up, we’d know that 26/24% is still too wet for that brand/type filament.
