If you print ABS, ASA, PC, nylon or any of the other higher-temperature materials in an enclosure, air filtration quickly becomes one of the most useful upgrades you can make.
A Nevermore-style filter is a recirculating chamber filter. It doesn’t vent fumes outside the printer — it pulls air from inside the enclosure, passes it through the media, and returns it to the chamber. That same air gets treated again and again during a print, which is exactly why media choice matters so much.
Good chamber filtration cuts down on odour and gas-phase VOC build-up inside the enclosure while helping to preserve chamber heat. It’s a genuinely useful part of an enclosed printing setup, but it’s worth being honest about what it isn’t: it’s not a magic “safe air” button. Room ventilation, sensible material choice and where you put your printer all still matter.
We’re introducing three new filtration media from Miranina, made in Canada and Nevermore-approved by Ondsk4, the creator of the Nevermore project itself:
- Boreas — acid-free activated carbon
- Notus — activated alumina with potassium permanganate
- Zephyr — a ready-mixed blend of Notus and Boreas
Here’s what each one does, why these media are a good fit for enclosed 3D printers, and how to pick the right one for your setup.
A quick primer: how filter media works
There are two main mechanisms at play in chamber filter media: adsorption and chemical oxidation.
Adsorption
Adsorption is where gas molecules stick to the internal surface of a porous medium. Activated carbon is the classic example — it has an enormous internal surface area and is very effective against many of the odours and VOCs that 3D printing produces.
The catch is that physical adsorption isn’t always permanent. Heat, humidity and saturation can all reduce how strongly some compounds are held. That’s one of the reasons media quality matters, especially in enclosed printers where chamber temperatures can climb during ABS, ASA or PC prints.
Chemical oxidation
Potassium permanganate (KMnOâ‚„) brings a different mechanism to the party. Instead of relying only on physical storage, KMnOâ‚„-based media chemically reacts with certain gas-phase contaminants and turns them into less volatile compounds that stay locked in the media bed.
This is genuinely useful in an enclosed printer chamber because carbon and KMnOâ‚„ media work well together:
- Activated carbon gives broad-spectrum VOC and odour adsorption.
- KMnOâ‚„ media adds chemical treatment for reactive compounds that carbon may not handle as consistently, especially in warmer chambers.
- A mixed setup gives you both mechanisms in one filtration system.
One thing to be clear on: these media target gas-phase contaminants and odour. They aren’t the same as HEPA filtration and shouldn’t be treated as a complete particle-control system.
Boreas: the workhorse carbon
Boreas is acid-free, steam-activated carbon in 3 mm pellets, with a substrate surface area of 1,250 m²/g. One 2.15 L vacuum-sealed bag (around 1 kg) fills a Nevermore StealthMax completely.
The acid-free part matters more than it sounds. Some cheaper carbons are acid-washed or chemically treated, and unsuitable carbon sitting near your aluminium extrusions, steel parts, rails, bearings and electronics can speed up corrosion. Boreas is steam-activated and acid-free, so it’s a safer choice for the inside of an enclosed printer.
Boreas is the right pick when you want broad VOC and odour adsorption without the extra cost or handling considerations of KMnOâ‚„-based media.
Best for
- PLA, PETG, TPU and other lower-odour materials
- Lightly heated (below 50C*) or unheated enclosures
- Printers where you mainly want general VOC and odour reduction
- Anyone who wants simple, clean activated carbon media
PLA, PETG and TPU are generally lower-concern than ABS or ASA, but they’re not emission-free. Boreas gives you a sensible baseline for everyday mixed printing, especially when the chamber isn’t running hot.
* Activated carbon looses all holding capacity for VOCs above 50C and starts actively releasing stored VOCs at high-temperatures.
Notus: the chemistry option
Notus is activated alumina beads infused with 8% potassium permanganate. It’s bright purple when fresh and gradually turns grey as the KMnOâ‚„ is used up.
Notus uses the same active oxidiser you’ll find in potassium-permanganate media like Nevermore Scorch, but on a different carrier substrate: activated alumina rather than zeolite.
That carrier matters. Activated alumina is porous, stable and widely used as a substrate for gas-phase filtration media. In Notus, it helps bring VOCs into contact with the KMnOâ‚„ so reactive compounds can be treated through a combined adsorption-and-oxidation pathway.
Activated alumina is also hygroscopic. In a recirculating printer chamber, the same enclosed air passes through the media repeatedly, so the alumina has plenty of opportunity to pull some moisture out of that air. This can help stabilise humidity around the filter bed and support the KMnOâ‚„ chemistry — but it isn’t a substitute for drying your filament properly before printing.
Notus is particularly useful in hotter chambers because it isn’t relying purely on carbon-style physical adsorption. Its performance still depends on airflow, media loading, chamber conditions and print time, but it’s a strong fit for the materials where odour and VOCs are most noticeable.
Best for
- ABS
- ASA
- PC and PC blends
- Heated chambers
- Anyone who wants chemical treatment alongside adsorption
ABS and ASA are the clearest use case here because styrene and related aromatic VOCs are a known concern with those materials. Notus is also a good choice for other high-temperature enclosed printing where you want something more than carbon-only filtration.
Colour-change tip
The outside of KMnOâ‚„ media can turn grey well before the centre is spent. Don’t assume the whole batch is finished just because the surface has changed colour.
Crush a bead to check. If it’s still purple inside, there’s plenty of active KMnOâ‚„ left. If it’s grey all the way through, it’s time to swap the media out.
Replacement timing depends on print hours, filament type, chamber temperature, humidity and airflow, so there’s no single magic number — the bead test is the most reliable guide.
Zephyr: the balanced one-bag option
Zephyr is a ready-mixed 60/40 V/V blend of Notus and Boreas — an alternative to Nevermore Boost-style mixed media. One 2.15 L bag (around 1.6 kg) fills a StealthMax.
The idea is simple: most enclosed printers benefit from both broad-spectrum carbon adsorption and KMnOâ‚„-based chemical treatment. Zephyr gives you both in a single bag without having to mix the two yourself.
It also makes refills cleaner. KMnOâ‚„ dust is the part you really don’t want floating around during media changes, so a pre-mixed product is a practical choice for regular use.
Zephyr isn’t as specialised as running pure Notus, and it isn’t as low-cost as running pure Boreas. It sits in the middle: a balanced option for anyone who prints a bit of everything and wants one cartridge that makes sense across multiple materials.
Best for
- Mixed-material workflows
- Anyone who prints PLA/PETG sometimes and ABS/ASA other times
- One-cartridge setups
- Anyone who wants both carbon and KMnOâ‚„ media without mixing separate bags
- A simple “pour, close the cartridge, print” solution
What about zeolite-based media?
Zeolite-based KMnO₄ media — Nevermore Scorch being the obvious example — is also a perfectly valid option for heated printer chambers. Zeolite and activated alumina are both porous substrates used in gas-phase filtration, and both can be paired with potassium permanganate.
The difference is the carrier substrate.
Notus uses activated alumina, a common carrier for KMnOâ‚„ in gas-phase filtration. It’s also hygroscopic, which makes it an interesting fit for a recirculating printer chamber where the same enclosed air passes through the media again and again.
Zeolite has its own strengths and is a perfectly valid filtration material. Even though Zeolites have a more carbon like surface structure (great for capturing VOCs), impregnating it with KMnO4 partially clogs these pores and so reduces the active surface for VOC adsorbtion. Here Alumina has an advantage over Zeolites.
For our range, the Miranina approach gives us a strong combination of activated alumina, KMnOâ‚„ chemistry and clean handling in a format that works well with Nevermore-style filters.
Which one should you choose?
| Your setup | Recommended media |
|---|---|
| PLA, PETG, TPU, unheated or lightly heated enclosure | Boreas |
| ABS or ASA in a heated chamber | Notus or Notus + Boreas |
| PC or other engineering materials | Notus + Boreas, or Zephyr for simplicity |
| Mixed workflow, one cartridge | Zephyr |
| Lowest handling complexity | Boreas or Zephyr |
| Maximum KMnOâ‚„ capacity | Notus |
If you’ve got space for separate filter stages, running carbon and KMnOâ‚„ media in dedicated cartridges is an excellent setup. In compact printer filters, a mixed bed is usually the practical answer — and that’s exactly where Zephyr earns its keep.
A word about Nylon: It’s main “nasty” by-products are Caprolactam (Pa6) and Laurolactam (Pa12), which are unreactive to KMnO4, and is being printed at chamber temperatures too hot for carbon. The recommendation on how to deal with this is active ventilation to outdoors, none of the common filter media will work for these unfortunately.
Airflow Matters
Media choice matters, but so does airflow.
A chamber filter needs to move air through the media bed repeatedly without simply bypassing it. Over-packed cartridges, compacted media, dust build-up or weak fans can all hurt performance.
For best results:
- Fill the cartridge properly, but don’t crush or over-compact the media.
- Make sure the fan can actually pull air through the filter.
- Replace media when it’s spent.
- Keep the filter sealed so air passes through the media rather than around it.
A recirculating filter works by repeated passes. The better the airflow path, the more useful the media becomes.
A note on handling and disposal
Notus and Zephyr contain potassium permanganate. It’s straightforward to handle in normal refill quantities, but it’s still a reactive oxidising material, so a few sensible precautions are worth the effort.
When refilling:
- Wear gloves.
- Wear safety glasses.
- Avoid breathing in dust.
- Use a dust mask or respirator during media changes.
- Wash your hands afterwards.
- Keep KMnOâ‚„ dust away from your eyes, nose and mouth.
Once KMnOâ‚„ media is fully spent and grey, small quantities from normal 3D-printer use can generally go in with your household waste, subject to local rules.
If the media is still bright purple, treat it as unspent reactive material and dispose of it through your local waste authority. Please don’t dump unspent KMnOâ‚„ media outside or anywhere it could leach into groundwater.
The bottom line
Boreas, Notus and Zephyr are three ways to approach the same problem: cutting down on odour and gas-phase VOC build-up inside an enclosed 3D printer.
- Pick Boreas if you want clean, acid-free activated carbon for general VOC and odour adsorption.
- Pick Notus if you print ABS, ASA or hotter engineering materials and want KMnOâ‚„-based chemical treatment.
- Pick Zephyr if you want one balanced media blend that covers most mixed-material workflows without the hassle of mixing it yourself.
A Nevermore-style filter doesn’t replace good room ventilation, and gas-phase media isn’t the same as HEPA particle filtration. But inside a recirculating printer chamber, the right media makes a real difference — less odour, lower VOC build-up, better chamber air management and a more pleasant enclosed printing setup.
All three are in stock now. If you’re not sure which one suits your printer or filament mix, drop us a message and we’ll happily help you work it out.
