On the Bambu product page, it says the working life of the desiccant is one month. On their wiki it says:
In addition, when it is not replaced for more than 3 months, the desiccant may also leak water, short-circuit, or damage the circuit or electronic components inside the AMS.
This is what my desiccant looks like after almost 5 months. I use the printer quite often.
I was surprised that there was no sign of moisture considering the information from Bambu above. It is just powder, the discoloration on the right side is not in the powder, but is just the glue that holds the two sides together. I am pretty meticulous about how I deal with filament and the AMS, so I would have expected a longer than average usage time. But it is hard to believe that it is this long with absolutely no signs of moisture. I was inspecting the package to see if there was some kind of seal I didn’t remove, but it looks fine.
I always dry new filament and put it in a vacuum heat sealed bag with silica desiccant. I make sure the tabs on the AMS are keeping the lid tightly closed, and when I exchange spools, I take out the old spool, close the lid (without the tabs), then tape the end of the removed filament and remove the tape from the new. I then open the lid, feed the filament end, close the lid and turn the tabs.
I once bought a bag of the stuff to use on my driveway whenever it iced up. I finally had an occasion to use it, but afterward I left the bag open in the garage and forgot about it, not knowing that it had such a strong affinity for humidity. I don’t remember now how long I left it for like that, but later after the weather had warmed up and I finally got around to putting it away I discovered that it had become a bag full of very watery calcium chloride soup. I had to throw it out. You never see anything like that with a silicone desiccant.
So, yeah, I do believe the warning about its potential to leak water.
I presume it’s more effective than silicone desiccant, and that is the reason why BBL chose to use it.
That is what I’ve read, that is has a strong desiccant effect. I am not sure of the difference between maximum capacity, but it is supposed to absorb moisture quicker and continue to absorb at a lower humidity level.
One of the reasons I use silica gel is because it is easily reusable and readily visible when saturated; you don’t even need the moisture color-changing kind. Try this experiment with a bag of silica gel: Place it in the microwave on defrost for 7 minutes. The silica will dry out and become cloudy. After it cools, place it in a glass of water. It makes a cool sound similar to ice melting. After five minutes or after the “cracking” noise stops, drain the water and pat down the beads with a paper towel. The beads should now look like glass with all the water absorbed. That’s how you can tell even without color changing. You can repeat this process multiple times, although eventually, thermal stress will crack the beads, making them dusty and unusable unless kept inside the bag.
I have yet to find a good guide on when to use calcium chloride vs silca gel vs molecular sieves vs whatever else there might be. Some seem to absorb faster than others, but may not be effective at the lower RH levels. I thought it was the calcium chloride that was noted for giving off a white dust onto things. Until I’m able to sort this out, I’m tempted to use all 3 at the same time in overkill amounts just to be sure I’m able to maximally desiccate my filaments.
I don’t know about calcium chloride. Comparing silica gel and molecular sieves, the pros and cons as I understand it:
molecular sieves:
are effective down to 0% RH
are effective at high temperatures (> 100°C)
can absorb ~20% of their own weight
need > 300°C for drying
silica gel
starts getting slow below 20% RH
doesn’t work at elevated temperature
can absorb ~50% of its own weight
needs 80-100°C for drying
is a bit cheaper
So silica gel holds up longer and is easier to handle, but isn’t as effective.
So I think each is suitable for different uses.
E.g. when you want to dehumidify the air in a dryer there is no way around molecular sieves.
In a sealed filament bag, silica gel might hold up longer until you have to exchange it because of the higher capacity.
I use molecular sieves exclusively, because I got 1,5 kg for free at work and I like the 0% RH.
Oh and I think combining different dessicants only combines the disadvantages: E.g. when you combine silica gel and molecular sieves, the mol. sieve will dry the silica gel and is quickly saturated. after that, you only have the worse efficiency of silica gel but you still have to dry at two different temperatures. Drying the molecular sieve is really a hassle compared to silica gel.
The combination also won’t work at higher temperatures (e.g. inside a filament dryer).
So depending on your criteria, I would either use one or the other but not both together.
Fwiw, i now dry silica gel at 140C, and doing so makes it extra dry. Enough to reach 1% RH, at least initially. Still low enough temp it doesn’t seem to bother the color indicator.
