Really sorry if this bores 99% of you,
I take a shiney new 1KG roll of filament, and put in an air tight cereal box. Inside said box is a generous portion dry drying beads. Trouble is the filament is wound B****y tight on the roll, how on earth does the desiccant work on anything but the top 4 or 5 layers. By all means print a 10 minute task and then wait 2 days for the next 5 layers to dry…… that can not be right !!!
You need to use hot air dryer, if you think the filament is wet it takes months to dry with just desiccant beads.
But the same problem happens with hot air, you just need to rely on diffusion.
Thinking of adding a 10watt or so heater to the box but still think the issue remains. If I was to get a heated case how long it need to dry a KG. not talking something that is dripping (!!!) but a cheap new reel?
Unfortunately it varies with the dryer and the dryness of the make-up air coming in. For PLA mostly I just throw it in overnight, but I have a big accurately-controlled food dehydrator that I use that is guaranteed not to overheat.
The way you know if it is dry (or needs more drying) is to weigh it. Initially it might lose 1% in 4 hours, as it dries the curve flattens out.
I dont think you can dry filament just in a box with desiccant, Here is some info with a chart on how long it takes in a forced air dryer, but like krellboy mentioned it varies with the dryer.
Thanks Rusty35 ( and the others) 12 Hours…… 12 flip flap **** hours…I will end up spending more on me electric bill then the price of the Filament …
Desiccants can’t take out the moisture that’s already absorbed by the filament. They are meant to take the moisture out of the air in the container to keep dry filaments dry.
So if the filament is wet, you would have to dry it in a dryer or an oven first. Then put it inside a air-tight container with desiccant to prevent it from absorbing moisture from the open air.
I am going to set up me old toaster oven in the shed then !!!
Many thanks folks for humouring me, ‘tis appreciated.
If you live in a dry climate it may not be huge issue, its fairly dry where I live and I don’t have to dry most pla, some of my petg comes out of the bag wet and some don’t, but storing pla and petg isnt an issue for me.
You can get a cheap Creality 4 bay dryer (like $140 US) or something like that and that is a good way to dry your new rolls, then stick in those boxes with the desiccant to keep them dry. Thats the easiest way. It isnt that much power to dry that method. I just use the AMS to dry mine and try to get them in 4 at a time or use an AMS HT to dry one at a time. I’ve seen that reality dyer in person though and its pretty good.
The filament only needs to be dry for the bit it’s printing. We cannot dry fillament completely, because a) most people do not have the equipment and b) if you could you would not as completely drying would change the molecular structure. So it only needs to be dry enough. 
Filament will always move toward equilibrium with the environment in which it is stored. If you put wet filament in a box with lots of desiccant, moisture will be drawn out of the filament, into the air, and into the desiccant. Given that desiccant has a great capacity to absorb and holds moisture, this will dry out your filament. But the speed will likely be slower than if you actively heat it. But it may be fast enough for your purposes.
Don’t use cheap fillament is my first advice. It causes more issues than its worth. Especially if using AMS units. If using AMS units, never use cardboard rolls, always plastic, cardboard does not roll well on the rollers, causing bouncing and making the AMS units fault with tangled spool errors.
The problems with cheap fillaments, often means thickness tolerances, humidity levels, colour not the same roll to roll, and the list goes on. Somethings are not worth a compromise - fillaments are one.
So I respool my filament from one cereal dry box though a drying chamber (48x18x18) that contains a two pounds of desiccant in trays in the bottom and fans that circulate the air (heated if required for that filament) on to a second spool in a new cereal dry box. The the motors will transfer 1kg over a 24 hours cycle.
Target Relative Humidity (heat if required):
Toaster ovens usually do not have precise temperature controls, so you are likely to end up with a solid chunk of melted plastic. This is why dedicated filament dryers exist.
If you have an enclosed printer, you can use it to dry filament safely. Then use the dessicant and cereal box to keep it dry.
I was about to say the same.
It doesn’t make sense to use an alternative method when filament dryers are so cheap and good now.
Plus I would never use a toaster, oven, airfryer, etc, after drying filament in it.
Water molecules are just slightly larger than a single oxygen atom. The roughness and size of cracks in the surface of 3d print filament are huge compared to the size of water molecules. There is obstruction but it’s way less than people may realize.
This is the biggest reason I used a filament transfer method. I know the heat can break the bond, but the inner filament lines can just as easily drop vapor that is then picked up by the outer lines in the physical transfer/cooling after the dry cycle.
I’m not saying mine is the best. At first I didn’t know that putting the filament in direct contact with the desiccant would cause additional issues, but I honestly think it’s getting better.
Forgot to say that if you have an AMS 2 Pro, you can dry PLA in it.
How do you know the new filament is wet?
My location is not particularly humid, and I haven’t had to dry PLA so far during the years of printing.