I found Wander Ridge vacuum bags recently. Far superior to any of those blue bags with a sticker for a valve. These are heavy weight with an actual valve on it, and the pump that comes with it is very strong and fast. 20 out of 20 held up compared to over 50% of the others failing
Those blue ring bags have been driving me crazy with the failure rate of the valves. Your post was all the endorsement I needed to try the Wander Ridge product. Ordered. I’ll report back on my experience.
I learned decades ago that water vapor goes right through plastic, you need desiccant no matter how IP-rated your case is. The Home Depot Husky cases with Hydrosorbent desiccants (not all desiccants are the same!) keep my filaments down to 10% pretty consistently.
When I open a new roll and put it in the case the humidity jumps up and then drops back to 10% over the course of the next day or so.
With the clear covers I can monitor the humidity and check inventory without opening the box.
Do those work with the vac pumps that come with the generic vacuum bags with the flat blue valves?
The one on the left is the one that comes with the 20 bag kit, the one on the right is what came with the blue sticker valve bags and it does work, but does not seal tight to the valve so you have to hold it in place until done. The one it comes with makes a tight seal that makes it stick to the valve until it is ready to be removed. It’s also got twice the speed of removal.
Ok, thanks for that. I’ll order one of the 5-bag sample packs and see how I get on with the pump i have.
What have you noticed about Hydrosorbent desiccants that makes them better than others?
[Edit: I have no idea why the link is showing that ganja image. Amusing, 
, and a sign of the times, but it’s not my doing. 
It doesn’t appear anywhere on the Hydrosorbent desiccant page that I linked to. ]
They seem to absorb a lot more moisture before getting saturated. I tried a couple of less expensive (per 500g package) desiccants from Amazon, and the humidity in my (mostly-)sealed enclosures rose a lot faster than with the Hydrosorbent.
Which kinda makes sense, if someone can cheap out on quality and sell it for less on Amazon, they will definitely do so. Hydrosorbent has been around forever, and I learned a valuable lesson by trying to save some money.
Interesting! I had always just assumed it was basically all the same, other than possibly different diameter spheres. Consequently, I never looked into it, nor ran any experiments to quantify how big the difference might be..
How does it compare to Dry 'n Dry or Wisesorbent? Those are two brands I have some familiarity with. There’s not a lot of space for desiccant inside the Bambulab AMS’s, so if Hydrosorbent truly is head and shoulder better, that would be one place I could see putting it to use over the others.
I bought a bunch of Wisesorb, and then some bags to put it in, and while it brought the humidity down in my enclosure, swapping in the Hydrosorbent gave much better results.
I did a little digging. **EDIT: I posted some wildly wrong information. I’ve deleted it here to avoid confusing people who read this thread int he future. I’m so sorry. 
**
Wait! This seems like a disconnect. Where are you seeing 500C? I see two distinct Hydrosorbent desiccants: silica gel (that I linked to above) and molecular sieve. Hydrosorbent recommends recharging the silica gel at 125C, and their 4A molecular sieve at 320C.
No, I’m talking about the Hydrosorbent Brand Silica Gel Desiccant as at:
and other sources. It recharges at 115°C to 125°C for approximately 2-3 hours, though I’ve found by experimenting with weight that it depends a lot on your oven (if you can’t crack the door to let the humidity out it takes a lot longer, and “Exceeding 160°C will permanently destroy its porous structure, while exceeding 125°C can damage the organic dyes in color-indicating gels”. My oven isn’t nearly that precise, so I need to fiddle a lot.
Also note that silica gel can be recharged in a microwave, but the Hydrosorbent cloth bags can catch fire(!) so that also takes some care.
I didn’t realize they made molecular sieve desiccants, that’s not something you can recharge in your home oven at 320C (600F) for 24 hours.
I think I f***** up. I conflated sodium polyacrylate (the stuff used in baby diapers, among other things) with hydroserbent desiccants, and the super high temps needed to reactivate molecular sieves. These are not the same things. I’m doing more reading and have edited my post to note that I think I posted wrong information. (I’m leaving the post there but edited. I try to I own up to my mistakes.)
Sorry for muddying the waters here. I feel like such an idiot.
Follow up: I’m tapping out on desiccants. I got badly mixed up as I went down a rabbit hole of research papers. This stuff is waaaaay more complicated than I thought; turns out desiccant is a topic of very active research by industrial chemists and researchers. There’s a lot there, and… I mixed it up in my head. I should know better, but I wandered into my Dunning-Kruger zone.
I’ve blown up my own credibility. So I’m going back to edit and remove my just plain wrong information so that it doesn’t pollute the otherwise useful information you all have rounded up.
There’s nothing wrong with mixing up complicated information, realizing it and correcting it. In fact, few are as transparent as you are. 
Don’t let a single case discourage you. Yours is the kind of inquisitive curiosity that moves communities forward.
Looking forward to your experience with the Wander Ridge bags as I need to order new bags soon.
Desiccant is a learning experience. It took me a bit but I got a process down that I do once a week as a PM item. I have 7 ANS2 and an HT, plan to add two more HT, one for each machine, I like the HT. (oops side tracked) SQUIRREL! I have the desiccant containers in each, and spool containers for a total of 10 containers each, two in the HT. I have two bottles of desiccant, one blue, one orange. I tried drying in the Dehydrator, the blue dries quickly but the orange just gets wetter, turns dark green. So if I started week one with blue, I dump that out into glass bowls and put them in the Dehydrator for 2-4 hour depending on saturation, and swap in the Orange. When the desiccant has been “dried”, I pour it into the bottle and store it. The following week I dump out all the orange and swap in the blue, then I spend about 15-20 minutes per batch drying the Orange in the microwave. 5 minutes 50 % power, open the oven, pull out the desiccant and roll it around on a metal pan to cool while leaving the microwave door open to vent out excess moisture. After the orange has cooled a bit and starting to return to orange, I pour it back into the glass container, and another 5/50 in the oven, and repeat. Usually takes about 3 cycles but it comes out at roughly 95% dry as some are still dark in color. I then pour it into the container after it has cooled. Next week rinse and repeat. If the AMS are still showing less than 11%, then I skip that week.
My AMS all show down to 0% after a day or so and slowly creep back up to the teens, so they are either pulling more moisture from the filament in them, or are getting moisture creep through the seals, Any time I open the lid on one the RH jumps to 38-40%, so I try not to open if I don’t have to, and when I swap a roll I try to do it as quickly as possible.. RH% in my shop is above 50% most of the time, which PETG seems to like to suck up. PLA though, never an issue, just trying to keep my PETG print ready.
Doesn’t hurt to keep the AMS as dry as possible and if I have to spend an hour or two a week to do it, worth every minute of it.
On topic but offtopic, just want to mention that if you’re starting to use Activated Alumina pebbles, you should know they are mildly abrasive against itself. This means that if you put them in a holder in the CENTER of a spool, and that spool rotates all day as its being fed, it’s going to act like a rock tumbler and generate dust. And that dust falls down into your AMS etc. So only put them in a spot they can be stationary, or if you do the spool-core thing, PACK that thing 110% full so there is no internal grain movement when you turn it.
Nah, no credibility problem. I wouldn’t worry. But you are right - it’s a very important area in materials science and used in a number of different industries.
Desiccants and behaviors are definitely complicated. Simple at first blush but lots of hidden details and on top of it all you can’t actually see changes without indicators that change too late for us or getting desiccant so wet it has visible water. You have to use hygrometers and such to really know where you are.
It’s dynamic too. Temperature factors in and water tends to move. There is a lot of detail but it’s not hard stuff. Just takes a while to get a good mental picture of what goes on.
Yep. Understanding the basic physics of water can go a long way to understanding how Desiccant works. Simple physics, the basis of hydrodynamics is that water always seeks it’s own level, regardless if its liquid or gas, even as a solid. You put in something dry with something wet, seal it, at some point there will be equilibrium between the two items. Also keep in mind that moisture will tend to move from cold to warm as well. If you have a cool AMS with wet desiccant in it and put in a much warmer, dryer spool of filament, the filament will pull moisture out of the desiccant. It’s just how moisture works. Many argue that you can’t tell the moisture content of filament based on the RH% in the AMS, but actually you can based on hydrodynamics. It doesn’t happen right away, but over time as moisture reaches equilibrium in its environment. Example is if you have an AMS that has been sitting for several weeks with 4 rolls and fresh desiccant, and it went to 0%, then up to 11% and stays, that means your filament is at approximately 11% moisture content as the environment is at equilibrium. The desiccant pulled out all the moisture in the air inside the AMS when it reached 0%, then the filament itself released it’s moisture until the desiccant reached its maximum storage capacity, so between the desiccant, the air, and the filament, there is 11% moisture content, the caveat though, it is not a true indicator of actual moisture content of the filament, but an indicator if it is dry enough to print with. This is all verifiable information as well.
A faster way to pull moisture out of filament inside an AMS is to load it with warm, dry desiccant.
Another thing to keep in mind is that when you set the AMS to drying cycle, without changing out the desiccant, the desiccant will also release it’s moisture so you tend to dry both, though it wont get hot enough in the AMS to completely dry the desiccant out unless you have it sit for days on dry cycle. I struggled with that at first until I went down the rabbit hole on how moisture works.
Warmer air holds more moisture too, which is one of the reasons the RH climbs in the AMS during a dry cycle. If you are drying it in a humid environment, it is also fighting the humidity being drawn in through the vents. Thankfully I have never encountered a wet AMS as I have seen others post about.
What I have found since I started printing is that as long as I keep exposure to the shop air (50% or higher most times) to a minimum, I don’t need to dry the filament, and only dry filament IF its one that should be dried before printing, like Wood PLA, Support material, TPU, or ABS. I no longer dry PLA or Silk PLA, only dry PETG if it bubbles or strings. I don’t even put desiccant in the bags with the filament either, just out of the AMS into a bag and seal it, put it on a shelf until needed. A quick way to determine if a newly opened spool requires drying is a temp tower, and only if its a new brand or questionable seal on the bag where it lost vacuum from the factory.
How could I miss this topic!! 
I have been using those simple bags for quite some time, but the permeability is really terrible. Inside each bag sits a Bluetooth hygro-thermometer BTH01 from AliExpress and a curved box with molecular sieve as dessicant, about 80-90 ml. Most bags achieve 3-6% RH and I have to replace the desiccant roughly every two months when I don’t open the bags.
In the AMS on the other hand, humidity is tacked to 0% until I open it. It takes a day to return to 0% again and I replace it maybe twice a year, although I open it frequently. While that is to be expected, it’s still nice to see it confirmed in real so clearly.
I recently discovered the eSun bags, think it was another thread here. They have a proper rubber valve. But I doubt that they are less permeable. The plastic isn’t much thicker.
I store the filament that is ready to use in an Ikea wardrobe drawer and extra refills in the cellar. My plan now is to cover the inside of the drawer with vapor tight panels and glue the seams. Then add a hinged lid with seals and just have a single big dessicant container inside.
When I asked chatgpt for the best material, it surprisingly suggested Forex (PVC foam board), because it is very easy to machine, very vapor tight and cheap. solid PVC would be even better but not as easy to work. I think I will follow that route.
The molecular sieve really is on another level regarding water adsorption. It relentlessly pulls humidity down to 0% when you don’t constantly resupply moisture. And while it can only hold water up to 20-25 % of its weight, while silica gel takes up to 50%, that completely flips at lower humidity values. At 10% or even 5%, the water capacity of silica gel drops to almost 0 while the capacity of MS drops quite a bit but is still there.
By the way, The BTH01 are great units! I have more than 20 in use and compared them against a Sensirion SHT31 as reference and all are within 2-3% of it down to 0%. Excellent value for money! I also have a Bluetooth → Wifi bridge so that I get notified by the app, when any sensor exceeds a threshold ( i use 10%) sorry for repeating myself in different threads 
