AMS Desiccant: When to Check It, When to Dry It, What to Buy
Published · Applies to every AMS and AMS lite
Short version
Check the desiccant in your AMS every two weeks. Orange beads are working, dark purple ones have stopped. Bambu sets three months as the outer limit and gives a reason for it: fully saturated desiccant holds liquid water, and the wiki warns it can eventually leak. You do not have to keep buying it: dried at 80 to 90 degrees, the same beads go back to orange and back to work. When you do replace them, buy orange indicating beads rather than blue. The blue kind gets its colour from cobalt chloride.
Why there is a time limit at all
Desiccant is the most boring part in the machine, so the maintenance note attached to it rarely gets read. It sits in Bambu's wiki, on the page about desiccant status:
“If the desiccant is not replaced for more than 3 months, moisture leakage may occur, which can severely cause short circuits or damage to the internal circuits and electronic components.”
Worth reading carefully: this is a manufacturer describing a worst case, not a wave of reported failures. We have not seen fried AMS units piling up in the forums. What it does explain is why there is an interval at all. Fresh desiccant is a print quality matter. Fully saturated desiccant is holding liquid water, and Bambu would rather it did not sit in there indefinitely. Hence: check every two weeks, swap when the colour says so.
Reading the colour
Two kinds ship with Bambu machines and they read slightly differently.
| Type | Dry | Saturated |
|---|---|---|
| Silica gel | Orange | Dark purple |
| Molecular sieve | White particles plus orange indicator beads | Indicator turns dark purple, white particles turn brown |
Bambu rates the molecular sieve higher: it holds up better in warm drying environments and pulls the humidity down faster at room temperature than plain silica gel. If your AMS runs next to an enclosed printer that is warm for hours, that difference matters.
The one that looks like grease
Older units shipped a calcium chloride desiccant that turns into a gel as it saturates. Bambu spells it out because people get it wrong: this is not grease. It is fully soaked desiccant. Smearing it onto a linear rail or bearing, which happens, will damage the part.
Stop buying it, start drying it
Saturated silica gel is not used up. Drive the water out and it works again, and Bambu documents both routes.
In a household oven
Spread the beads on something heatproof, a ceramic plate or a glass dish. Set the oven to 80 to 90 degrees Celsius. Do not go above 100: higher temperatures wreck the internal structure of the gel and it stops absorbing for good. Lightly purple beads need one to two hours, fully dark ones two to three. Let them cool, then check that they are orange again.
On the printer bed
Put the beads on the heatbed and cover them with a heatproof container or a cardboard lid. The bed heats less aggressively than an oven, so allow three to four hours and turn the beads every half hour. The convenient part: you can dry filament and desiccant in the same session.
In a filament dryer, if you have one
There is a third route that gets overlooked, and for anyone with a dryer it is the most convenient: put the beads in the machine you already own. MakerWorld is full of desiccant spools for exactly that, containers shaped like a filament spool that sit on the dryer's spindle and hold loose beads behind a perforated wall. The popular ones run into five figures of downloads, and there are versions fitted to the AMS 2 Pro, the AMS HT and to third-party dryers such as the SUNLU units.
The trade-off is time. A filament dryer tops out well below the 80 to 90 degrees an oven gives you, so the same batch takes noticeably longer. In return you get a machine built to run unattended for hours, and you can regenerate desiccant while a spool dries in the same chamber.
Orange, not blue
Indicating silica gel comes in two colour systems and they are not equivalent. The blue-to-pink kind takes its colour from cobalt chlorideThe dye that makes blue indicating silica gel change colour. Classified under REACH as a category 1B carcinogen and listed by ECHA as a Substance of Very High Concern.. The orange-to-purple kind uses a different indicator and contains no cobalt. Both dry your filament equally well.
Where it is not allowed
Cobalt chloride is classified under REACH as a category 1B carcinogen and sits on ECHA's list of Substances of Very High Concern. The practical result is that blue indicating gel has been kept off the European market since the late 1990s, and its use is restricted in the UK, Australia and Canada as well. It is not banned worldwide, and in the United States it remains perfectly legal to sell and buy. That is why the highest-reviewed indicating beads on Amazon are still blue, with thousands of ratings behind them.
Why we would skip it anyway
Legal and sensible are different questions, and the answer here depends on what you actually do with the stuff.
Sealed inside a shipping crate, blue gel is a non-issue. AMS desiccant is the opposite of sealed: you pull it out every couple of weeks, look at it, tip it into a dish, put it in the oven you cook with, turn it by hand, let it cool and pour it back. That is repeated handling plus heat, in a kitchen.
Two things follow from that. Safety data sheets for cobalt-impregnated gel carry the warning EUH208, contains cobalt (II) chloride, may produce an allergic reaction, and note that handling can generate respirable dust. And the occupational exposure limit for cobalt chloride is 0.02 mg/m³, against 6 mg/m³ for silica gel itself, a limit three hundred times stricter for the dye than for the material carrying it. At least one manufacturer states plainly that blue gel is not recommended for drying in a household oven.
To be fair about the risk
This is not a poison scare. Chemists point out that cobalt salts are mainly a concern when swallowed, that they pass through skin poorly, and that heating to around a hundred degrees is unlikely to drive off meaningful amounts. Nobody has been harmed by looking at a blue bead.
The argument is simpler than danger: the orange version does the identical job, costs about the same, and carries none of this. There is no upside to the compromise, so why take it.
What we would get
Plain orange indicating silica gel beads, bought in bulk rather than in sachets, so you can refill the AMS containers and keep a batch drying in rotation. Two pounds is enough for one AMS with spares; five pounds makes sense if you run several units or also fill dry boxes. Molecular sieve is the upgrade if your setup runs warm.
Viktairy orange beads, 5.5 lb on Amazon (4.8 stars across 651 ratings) or the smaller VOISEN 2 lb pack. Neither is tested by us; both are established sellers with the orange indicator.
Print the containers
Loose beads need something to hold them, and this is the rare case where the answer is simply to print it. MakerWorld has a whole collection for it, currently 21 designs, and the popular ones are popular by a wide margin: the leading in-spool holder sits past 68,000 downloads, and two of the AMS 2 Pro pod sets are above 40,000 each. They split by AMS generation because the compartments differ. Two further shapes exist alongside them: holders that sit inside the filament spool, and desiccant spools that go on a filament dryer's spindle.
Do not print these in PLA
The AMS 2 Pro dries filament actively, which means the compartments get warm. Designers state it plainly in their print notes: use PETG, ABS, ASA or PC so the holder survives the drying cycles. A PLA container in a heated compartment is a container that deforms, and the beads end up loose in the machine.
Two details are worth copying whichever design you pick. The better pods include a dust trap at the bottom, a small chamber for the fines that silica sheds as it rattles around, which otherwise ends up loose inside a unit full of moving parts. And the mesh is sized for beads of 3 mm or larger: smaller beads simply trickle out through the ventilation holes.
Most of these designs also tell you to keep the supplied slicer settings, typically a 0.16 mm layer height with two walls. That is not creator pride. The perforated walls only come out as intended at those settings, and printed at your own defaults the holes either seal shut or open up too far.
A rhythm that works
Two containers of beads, one in the machine and one in a jar. Every couple of weeks, glance at the colour through the window. When it goes purple, swap in the spare and put the used batch through the oven or onto the bed the next time you are printing anyway. Nothing gets thrown away, and the three-month warning never becomes relevant.
Sources. Replacement interval, the three-month warning, colour states for both desiccant types, the drying temperatures and times, and the calcium chloride caution all come from the Bambu Lab Wiki pages on desiccant status and desiccant replacement. Cobalt chloride is classified under REACH as a category 1B carcinogen and appears on ECHA's Substances of Very High Concern list; blue indicating gel has consequently been kept off the EU market since the late 1990s, with comparable restrictions reported for the UK, Australia and Canada, while it remains legal in the United States. The EUH208 allergy statement and the respirable dust note come from safety data sheets for cobalt-impregnated indicating gel; the occupational limits quoted (0.02 mg/m³ for cobalt chloride against 6 mg/m³ for silica gel) are ACGIH and OSHA values reproduced on those sheets. The counterpoint on ingestion, skin uptake and heating is the consensus view among chemists discussing the material. We have not run our own humidity measurements, so treat the performance comparison between silica gel and molecular sieve as the manufacturer's own. The printable containers are public models on MakerWorld, Bambu's own platform, in the “Filament Desiccant Containers” collection and among the dryer-insert designs; download counts and the material, bead-size and slicer guidance are taken from those model pages as published by their designers. We have not printed them ourselves. Checked August 2, 2026.