I suggest you to switch to desiccant without indicator and recharge them when you see the humidity rising.
Because the indicator is toxic, the blue one can cause cancer and even the orange one is suspected to cause cancer.
Just throw it away and buy bulk on ebay without indicator, it’s much cheaper then the one from Wisedry aswell.
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Following up on the above comments on the Rosahl solid-state dehumidifier membranes. A while back I came across CNC Kitchen’s video on these for filament drying and immediately liked that approach pretty much (didn’t like the hassle with desiccant).
So, I made a cereal storage box based filament drybox with the smaller Rosahl RS1 membrane, where you can directly feed the dry filament out to the printer. Works pretty well for keeping new unwrapped spools or pre-dried spools (were lying around at 60% rel. humidity for days/weeks before) at 15% rel. humidity. And power consumption is quite low with just 0.2W power at that level constantly. Made a bunch of 3D printed parts for it and it’s powered from USB. Search for “Filament Drybox with Rosahl RS1” on Printables for the 3D printed parts and links for accessories for assembly if interested.
I also grabbed a larger M-3M1R membrane which currently keeps a 50l storage box with 15 spools at constantly 15% rel. humidity. Also made a 3D printed mounting cover with USB supply but that’s not yet on Printables. Will add soon.
Yes, these Rosahl membranes are a bit costly but they are very, very efficient in the long term compared to regularly using some conventional filament dryer or even an oven to dry spools or recover desiccant. I use four of the RS1 based dryboxes with the filament types I use frequently which is still less than 1W of constant power.
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Thanks for sharing your results!
Presently, my main unresolved question: is 15% RH good enough? From measurements I’ve taken using wireless TH sensors, it seems I can drive RH all the way down to 0% if I use enough desiccant.
From a physical perspective, the lower the better of course. Previously I kept my spools in zip tie bags with desiccant at roughly 20% and never had issues with PLA, PETG, TPU or even Nylon (which I do not use often, though) and hence I’m happy with the 15%. In reality humidity actually is a bit less, around 10-12% which I cross-checked in the beginning with a decent temp/hum logger in the boxes along with the low-cost hygrometer. It’s just that these simple hygrometers don’t work that well in low humidity situations. But the ones I chose were not much off, other than these black square ones more often used.
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These are very intriguing.
Can you share a source where you bought these from?
There is a link on the Printables page.
Thanks!
Sorry I missed that in your post.
I admittingly got caught up in the Big Clive review of these devices.
These would make a great mod for an AMS.
Looks like it might be a bit of a PITA to get them shipped to the US, unfortunate.
I‘m not aware of some US reseller. chip45 ships worldwide, but will add some shipping cost. Note that the prices there include 19% German VAT which would be deducted when ordering from the US. There is Westside in the UK, not sure if that would be cheaper.
We all want to know: where did you get those plastic sealed containers & what brand/size are they? They look like Sistema boxes - are they?
They hold 4 to 5 spools. They are pretty nice.
If you’re not in North America, I don’t have another source for them, sorry.
The one thing I can tell you about plastics manufacturers is that none of them are interchangeable unless they meet an industry standard. This is partly due to competition and partly due to copyright protection. The concept of a sealable tub is not patent protected, but the individual footprint is governed by a proprietary mold protected under copyright law. This is a long way of pointing out the obvious: if anyone has tried to use a lid from one maker on another, and it fits, it would be a pure coincidence.
This is the reason why I purchased what hopefully will be my lifetime need in one buy. You can almost guarantee that once this mold wears out, the manufacture will discontinue the product and the new product will not be stackable on the old product. This is how plastics companies like Rubbermaid force consumers to throw out perfectly good tubs because of lost lids and lack of intermateability. It’s also why you rarely if ever see plastics companies offering their product as piece parts.
So the advice I would give anyone. Buy this product “NOW” if it suits your needs and buy a lifetime supply “NOW”. Because you won’t find a similar one at that size that isn’t part of a “collection” and it’s more than likely that as soon as the manufacturer’s mold has exceeded it’s life span, they will likely move on to the next product.
However, there was sufficient information in @Lexi link. If you look in the fine print, you will see the manufacturers SKU which in this case yields several online and brick and mortar vendors who sell the product.
https://www.google.com/search?q=FBA34060
I have 10 of them and I already find myself needing more. 
Luckily my local Home Depot keeps stocking them. I think I will end up taking your advice and grabbing some more while I can.
Looking for a source of inexpensive desiccant? Possibly ~$3/pound? If so, read on.
Dry&Dry desiccant, which is what I currently use and which seems to be quite effective, is made from amorphous silica (Source Reference:
https://s3.amazonaws.com/download.flukecal.com/pub/literature/SDS%20-%205128A%20Desiccant%20Cartridge%2C%205128-2680%20-%20Orange%20Silica%20Gel.pdf).
I did a quick search and found that certain types of cat liter appear to be made from exactly the same material. Examples:
https://a.co/d/702N0QK
and
https://a.co/d/8U1XLdo
and no doubt others as well. These were the first two I ran across that claim to be low dust. You can get it with or without color indicators. Since I’m using wireless TH sensors, I’m not sure there’s any need or benefit for color indicators. Also, I’m unsure whether there is any consensus as to whether “safe” color indicators exist. Perhaps someone here may have already researched the answer to that. I think by now we’ve all alreardy heard that the blue cobalt ones may not be safe, and there’s even some debate about the orange ones. Some of the cat litter color indicators are lavender, which I presume is simply the color you get if you blend of blue and orange together? Or maybe it’s something different. I don’t know.
There are even cheaper versions, typically referred to as cat liter “crystals”, but the knock against them is that they can be dusty. However, the second one I reference above uses that name yet claims to be 99.9% dust-free. The non-dusty or less-dusty versions seem to most often go by the name of “pearls”, and from the name alone I suspect they look a lot more like dry & dry beads.
Anyone tried cat liter pearls as a filament desiccant or have any kind of opinion on the matter?
By default, my conservative goal is to drive RH to zero and keep it there in the filament storage container. I haven’t yet worked out a formula for how much is needed to achieve that, but as a first pass it seems to be a lot more than what most people seem to be using. Hence, the search to buy it in bulk at a cheap price.
I was planning on just that when I first saw this post. I am currently deciding on which model to get, either M1J1R, M2J1R or a couple RS ones
Dollar tree has perfect boxes for 1 roll full. They also sell moisture absorber containers that work great as well similar to damp rid.
Can you provide a picture of one?
This comes down to competition and the relative bond strengths between water and filament, and water and desiccant. That sets where this equilibrium will settle.
It just comes down to which has the higher affinity for water. Water will leave the material holding it more weakly and move to the material holding it more strongly.
But it’s not quite that simple. As desiccant grabs more water, additional water will be held less strongly. Similarly, as filament gets wetter, the additional water will be also held less strongly. Very dry desiccant and very dry filament will tend to grab and hold the first water more strongly.
So how this shakes out will depend on how wet or dry the filament and desiccant are. Very dry desiccant and wet filament and the desiccant will go to town pulling water from the filament. But very dry filament and wet desiccant and the desiccant can act like a water source and let water move to the filament.
I think it’s this behavior that’s confusing things. Desiccant needs to be kept very dry to be effective - depending on how wet the filament is.
Hopefully that makes sense but it is how it works. The dryer the filament the more it wants water and the stronger it holds what it has. Same for desiccant. It’s that tug of war that sets which way the water will flow.
Edit to add - but without added heat to help break those bonds between water and filament, the process will be slower than with heat. Desiccant bags in bins with filament won’t be as effective in drying the filament since temperature is reduced from a drying oven. Not as much urging the water to let go of the filament. But they can help keep the air dry in the bin so the filament doesn’t get the chance to absorb it. And dry desiccant can pull water from filament in a tub/bin. It will just be slower because fewer molecules will have the energy to break free.
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Perhaps storing the filament rolls in an airtight container then filling with nitrogen or CO2 or even scuba tank air might be an effective way to keep the RH very low. If you want to go to that next level.
Almost. Over on a different thread @IslandBill is pursuing essentially that idea, but rather than a once-and-done purge, when that dry air picks up moisture from the filament (for the sake of argument, assume the purge air has 0% RH humidity to start with), you then purge out that newly moistened air and replace it with fresh 0% RH air. And continue cycling like that until it remains bone dry. That’s the theory anyway. He also plans to add heat to help it along that way as well. Because he’s in a humid tropical climate, it can’t rely on only just ambient air for the make-up air, because he has found it too humid for that purpose.
Dry N2 and CO2 would work great. Even air from a compressor gets dehumidified to an extent because of the pressure - it’s why compressor tanks have water drains.
@NeverDie - that’s true. If you store filament in dry “air”, as any water molecules leave the surface, they are less likely to be replaced or to return. Dry air is like having very active desiccant except any water in the air could return to the filament if the now “wet” air isn’t changed out.
High ambient humidity will cramp the style of dryers that use ambient air. They can heat the air which lowers the RH%, and it will get some of the water but not near as much as if the air was dry. There will always be a “floor” to how low you can take water content in filament when ambient air is humid. Switching to dry gases or using a desiccant pre-stage to pull the air through to at least dry it some, I think as you suggested in another thread, will help.
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