PenBBS 456 Vacuum Filler Review

Update history:
  • Preliminary review 15 Nov 2018
  • Adding background on vintage vac-fil pens & comparison against Wing Sung 601 – 16 Nov 2018
  • Extended-use review and more precise measurements: 28 Nov 2018
  • Failed filling system on one model 456, and separate model 268: 29 June 2019

The hotly-anticipated new release from PenBBS fountain pen has finally arrived.  It is especially ambitious for offering a vacuum filler at an unheard-of price point.   The vacuum or “plunger” filler is something of a rarity in modern pens — the best-known examples are the Pilot Custom 823 and TWSBI Vac series (Vac700, Vac700R, and Vac Mini).  It is actually one of the oldest “self-filling” pen systems, originally seen in vintage pens from Onoto starting in the early 1900s.  It is commonly seen in models from the 1930s-1940s  by Sheaffer, and in the Conklin Nozac and some Wahl-Eversharp Doric variants.  This mechanism usually affords pens both spacious ink capacities and fast filling, which make them perfect for travelers or heavy writers that go through a lot of ink!

Unfortunately, vacuum fillers require careful manufacturing and design to work reliably. Was PenBBS able to pull this off with a pen costing under $40?  Is this the pen for you or should you opt for another PenBBS offering or a different maker’s vacuum filler?  Let’s dive in and take a look!

History and Context:

This particular model has quite a history, first surfacing in Nov-to-Dec 2017 labelled with prototype photos calling it the PenBBS 268.  At the same time we saw a sneak peek of a prototype PenBBS vacumatic filler labelled as the 348.  Both generated a lot of excitement in the fountain pen community, because it’s rare to see pen manufacturers venture beyond cartridge/converter and piston fillers.  Frank Underwater covered this in his Dec 2017 Chinese pen news post.  A small and early batch of prototypes went up for sale on TaoBao and sold out almost immediately, but there wasn’t much news for months aside from teaser photos.  All PenBBS would say is that they were working on it and it would take a while.

Finally, in late October, after nearly a year of development and several other model releases, the first PenBBS vacuum filler launched worldwide as the PenBBS 456.  Update: in June 2019 PenBBS launched the model 268 as a cheaper, injection-molded vacuum filler.  I will be reviewing this separately.  So far we don’t know what the status is on the vacumatic fillerUpdatethe vacumatic model 348 is expected some time in 2019.

As a study in contrasts, Wing Sung, another Chinese pen company, also announced around the same time as PenBBS that they were experimenting with new filling systems for their fountain pens.  After a few months they managed to launch their model 601 featuring a “vacumatic” pump-filler that used a rubber diagram to provide suction.  Unfortunately this model had a very rocky launch, with early buyers complaining of leaks and problems from unreliable manufacturing quality.  Wing Sung did several rounds of improvements to the model 601 to address various manufacturing problems, and ultimately replaced the rubber diaphragm (which could wear out or break) with a superior pump mechanism using spring-loaded piston rings.  While the first iterations of the Wing Sung 601 had a lot of problems, I have the later model (without the diaphragm) and have been quite satisfied with it.

Wing Sung released early and then quickly iterated to improve their design — a business model we see a lot in my line of work (software).  PenBBS did the reverse, by polishing their design over a long R&D cycle before launching a refined final version.  But, was the wait worth it, and who won overall?



Clearly a lot of thought and refinement went into the filler final design — as you’d expect for PenBBS and for a pen that’s been in development for the better part of a year.   I haven’t tried enough of the other vacuum fillers for comparison, but the plunger system on the PenBBS 456 works quite well:

  1. Unscrew the knob and pull out the plunger
  2. Fully submerge the nib in your inkwell
  3. Press down the plunger with a fast stroke, and wait a few seconds for it to suck up ink. Now you have an initial fill (about 1/2 to 2/3 of the barrel), about 1.4-1.5 mL of ink.  To give some context, that’s quite a bit more than a converter (0.7-0.8 mL) and about the same as a full piston-filler.
  4. To get a 100% fill, pull back the plunger while submerged, invert the pen, and and press the plunger to squeeze out the air (holding down the plunger so it doesn’t suck back out).
  5. Re-insert the nib in the inkwell and press the plunger down all the way to finish filling.

Ink capacity is one of the big selling points for this filling mechanism, because it takes up less of the pen barrel than piston fillers do.  I measured it holding over 2.1 mL (!) when filled completely, and even a quick pump will suck up more ink than a converter can hold.  Of course, if you want the absolute maximum ink capacity possible, the PenBBS 308 and 323 come with O-rings for reliable eyedropper filling and will hold over 3 mL and there are a handful of oversized eyedropper-filler pens from India which will squeeze in over 5 mL of ink.

The plunger moves smoothly and easily, and when the knob is fully screwed in the plunger appears to seal off the feed by acting as an ink shut-off valve (a refinement also present on the Pilot Custom 823).  In theory, this seals the ink chamber to make the pen safe for flying,  but for extended writing you will want to unscrew the knob a little bit to allow ink to flow into the feed.  Unfortunately, either the pen holds a ton of residual ink or the plunger isn’t creating a full seal; I haven’t been able to exhaust the ink after screwing in the plunger, even after pages of writing including some dense scribbling. Perhaps a flaw, but a minor one anyway;  I have had good luck flying with PenBBS pens and even eyedropper-filled models as long as I keep the nib up during takeoff and landing.

Emptying the pen out is actually quite easy: you simply depress the plunger when it’s not in ink a couple times, and it’ll force out the ink and the pressure will even blow a fair bit of the residual ink out of the feed.  I haven’t had to flush the pen fully and change inks yet though — we’ll see how easy the process is then, because vacuum fillers have a reputation for lingering droplets of ink.

As far as manufacturing, the filling system feels robust, with no wiggle to the plunger rod and a tight seal all around.  (Update:) We did have problems with one specific pen out of a batch of 4.  The two weaknesses this filling system has are unavoidable with the mechanism.  First, you do have a plunger head that is physically moving and it may wear out over time (a problem with vintage vacuum fillers) — the place where the rod enters the pen is another place where wear or damage could occur. Second, because the steel plunger rod is in contact with the ink you should not use iron gall inks in this pen to avoid risks of corrosion. I know, I know: “stainless steel can be quite corrosion resistant.”  That’s fine for steel nibs that can be easily and inexpensively replaced. I routinely use modern, milder IG inks with some of my steel nibs; however I would not want to try to replace the plunger rod, if it’s even possible.

Update: problems with the filler on one pen?  After a few months of use, one of the pens developed a mild leak at the end where the metal piston rod enters the pen.  That’s a natural point of stress for this kind of filler — strain on it can crack the barrel or damage the seal… and that appears to be more or less what happened.  My partner carried the pen in their tightly-packed backpack, without screwing in the knob so that the metal rod applied strain against the seal causing this leakage.  Unfortunately this seems to have triggered a second failure that caused the plunger to come off the end of the piston rod somehow, and I can’t find it anywhere.  I think it’s fair to say that user mistreatment played a clear role in these problems, but this left me a bit concerned.  However nobody else has reported issues with this model so I’m going to chalk this one down as a freak occurrence unless something else happens.

As an aside, the plunger/vacuum filler is actually one of the oldest “self-filling” pen systems, initially patented in 1905 and used by Onoto from 1906.  In the 1930s-1940s, this filling system was used for the Sheaffer Vacuum-fil, Wasp, and some members of the Balance line, as well as the Conklin Nozac, and some Wahl-Eversharp Doric variants.  Richard Binder has a wonderful article on its history and how it was refined over the years.  Unfortunately, the materials used in vintage plunger-fillers often degraded and restoration is difficult due to the need to ensure the plunger and shaft achieve proper seals.  On the bright side, the techniques needed to restore these lovely pens have become more widespread over the years, and once restored with modern long-lived materials they are quite durable.  If you like the filling mechanism in the the PenBBS 456, it’s well worth seeking out one of the vintage vacuum fillers (from a reputable restorer, of course).

Overall, I think PenBBS did a top notch solid job executing the vacuum filler.  While we won’t know for years how durable it is, I don’t have any cause for concern yet.  Also, the gush of air and then ink as it fills makes it quite satisfying to use.


Let’s get the obvious out there first: although it is average in size, the PenBBS 456 is by far the heaviest pen they’ve manufactured (or at least up until the larger aluminum models).  Its dry weight of 29.7g capped and 19.1g uncapped make it roughly 50% heavier than most PenBBS models.  I find the extra weight is not excessive and gives it a sense of solidity that is satisfying, but fans of lighter pens will probably prefer the PenBBS 309 piston-filler over this model, tipping the scales at a comparatively featherweight 19.3g capped/11.1g uncapped.

If you feel the balance, it becomes clear that most of the model 456’s extra weight comes from the metal plunger rod.  Both the Pilot Custom 823 and the TWSBI Vac700R are similar in weight for this reason (within ~2g).  The PenBBS 456 works hard to balance out this extra weight toward the rear, but still ends up slightly back-heavy even when unposted. Initially this change in the balance made the pen feel awkward in hand (especially compared to the model 309) but I’ve gotten used to it and quite like it now. The pen does post securely, and although I prefer this one un-posted, thankfully it doesn’t seem to make the pen much more back-heavy.

Otherwise, the model 456 is true-to-form for a PenBBS release.   PenBBS manufacturing quality has consistently impressed me, comparing quite favorably to far more expensive turned-acrylic pens produced in the West.  That said, although they punch far above their price in terms of quality, they do lack a few refinements and adornments that you’d see with Franklin Christoph, for example.

The clips are one example: all PenBBS pens that have clips use bent-metal clips rather than fancier spring-loaded clips.  I haven’t had any issues with the clips so far, after carrying the similar model 308 and 309 clipped to my shirt pocket for a while — but some people strongly prefer the more refined experience that comes with a spring clip.  Nice to have, but it’s not a feature I’d pay an extra $100+ to get, especially given how well PenBBS clips have worked for me.

Anyway, for this model the fit-and-finish is generally excellent. My one complaint is that there is some roughness screwing and unscrewing the cap. It is hardly the first time I’ve seen this with metal threading, and a may be intentional to prevent the cap unscrewing accidentally; nevertheless this roughness is a bit jarring given the silky smooth threading on most PenBBS models.  The threads are not uncomfortable to grip however.  Otherwise the machining of the acrylic itself gives a smooth, perfect finish that feels lovely in hand.  It’s worth noting that a few of the PenBBS materials are somewhat softer and don’t produce as hard and smooth a surface — several of the cloudier materials have this flaw, including the one with bright blue veins.

Looking at the prototype,  which has plastic threading, I suspect the metal threading of the section was added to improve balance by adding some extra weight in the section.

Overall: quite happy with the construction, the weight is an interesting aspect, and while I have mixed feelings about the back-heavy balance the overall result is quite good.  It’s definitely not as bad as the Yiren 827 but remains to be seen how it impacts long-term use.


The model 456 pens feature the PenBBS F Waverly nib — I’ve reviewed them before for the model 308 (and smaller reviews for the 323 and 349 on reddit).  At this point I’ve lost count of how many PenBBS nibs I’ve inked and used, but it’s at least a couple dozen, and they’re quite consistent.  Almost universally they are moderately smooth, with perfectly aligned tines and a touch of pleasant feedback — not “buttery” smooth though.  Flow varies a bit depending on the filling mechanism, with the C/C fillers being slightly dry and the piston and eyedropper-filled models being somewhat wet.  Sometimes the nibs have a touch of baby’s bottom but never enough to be an actual problem in my experience.

The two-color nibs on the two model 456 pens I’ve inked feel a bit different than their normal F nibs and previous duo-color nibs from them.  I’d say they’re a bit smoother and wetter, and slightly broader writing. So far, flow is even and balanced on one pen and slightly irregular on the other, with less tendency than normal to show shading.  It is unclear if PenBBS has changed something small with their nib grinding at the same time as this model, or this is just the usual manufacturing variation.

Oh, and unlike the model 308, PenBBS has left plenty of room between the end of the nib and the cap.  This means if you don’t like the stock nib you can easily swap it for any of the other JoWo #6 nibs out there — including italics and exotic options such as flex and Zoom nibs.  Ink flow is generous enough that broad and italic nibs shouldn’t be a problem except for possibly extremely fast writing.


PenBBS also takes a semi-minimalist approach to ornamenting their pens, limiting decorations to the cap band and letting the material of the pen speak for itself.  Given that they tend to offer a large variety of lovely acrylic patterns, this seems like the right call to me; however, fans of more elaborate design elements may miss the engravings in the resin, medallions/jewels, or extra styling on the clip.

Here we should talk a bit about materials, because it’s a huge part of the PenBBS appeal. PenBBS generally produces their pens in a huge number of styles, and the pictured clear acrylic (“glass” in their store) is one of the simplest.  We’ve seen a handful of styles for this model so far (about 10 styles).  If past history holds, over the next few months we’ll see a variety of clear and colored demonstrators, marbles,  translucent swirls and ribbon materials, gradient marbles, and now a koi-fish pattern.  In my opinion the clear materials with ribbon or translucent swirls are especially striking, as are the marbles.  See a few examples from the PenBBS 308 & 323 family showing off the marble and swirl materials.

The main problem is that PenBBS sells the pens in small batches for many of the styles so you need to grab them quickly once they go for sale on the PenBBS Etsy store before they sell out.  By “quickly” I mean sometimes a matter of minutes — one of the model 456 styles sold out completely in under 10 minutes and limited editions usually sell out within a few hours for popular models.  The best way to find out what is coming up is by following the Instagram of the lady that runs the store.

Clear demonstrators are not my preferred pen style, but I wanted one for the new model to better show the workings of the new filler.  Although I prefer the more interesting materials, the result here is quite handsome.  I especially like the shape of the cap’s top, which elegantly splits the difference between a flat-top pen and cigar-shaped pens.  The cap seems like a small touch, but it just really sets off the look of the pen somehow. The plunger’s knob also has a nice taper to it. The overall shaping of the pen is both modern and refined, and I have to say it is quite lovely.

But since looks are in the eye of the beholder, I’ll let you judge.

Comparison vs. the Wing Sung 601:

I’d promised to compare against the Wing Sung 601, which was announced around the same time and also offered an unusual high-capacity filling mechanism.  Let’s be clear: these are radically different pens.  The Wing Sung 601 is a lightweight hooded-nib pen at less than half the price of a PenBBS 456, and it lacks the polish and refinement of the PenBBS.  The plastic is softer.  The hooded nib on the Wing Sung is acceptable but has a squared-off, angular feel to it that can make it scratchy when not in the sweet spot; although I quickly sorted that out by polishing with micro-mesh and now quite like the nib.  Although it’s a fun to use, the pump-filling mechanism on my late-generation 601 is a touch sticky.  It also inherits one of the flaws from the historical vacumatic fillers: it is an unholy pain in the derriere to clean out, because you have to slowly squeeze out individual drops of water to empty it between inks.  Plan on picking a single ink you love and sticking with it in the 601!  The arrow clip is cheap and a bit fragile — mine became permanently bent out rather quickly.  Overall, the Wing Sung 601 does not feel anywhere near as polished and refined as the PenBBS 456.

BUT (and this is a big “but” — I cannot lie) despite its flaws the Wing Sung 601 is a solid workhorse pen in its own right and I think you should buy one.  More accurately perhaps, it is the metaphorical dwarf standing on the shoulders of a giant; this is a precise homage to one of the greatest pens of all time, the vintage Parker 51 Vacumatic.  This means you get the extremely comfortable ergonomics and balance of the classic Parker 51, and the hooded nib resists drying out when left uncapped.  It is close enough that one member of the /r/fountainpens Reddit created a Frankenpen with parts from both a Parker 51 and a Wing Sung 601.  Wing Sung  improved slightly on the original filling mechanism by replacing a fragile rubber diaphragm with more durable spring-loaded piston rings.   Finally the ample ink capacity (somewhere between 2 and 2.5 mL) is hard to beat, and means that the pen that also lends itself to extended travel.   Hopefully Wing Sung will continue to address the remaining flaws of the Wing Sung 601 — but in the meantime I think it’s a solid buy at just $15.  Even if you have a vintage ’51, this is a pen you won’t worry about losing when you carry it around with you.


The PenBBS 456 impressed me with its general quality and how successfully they executed the ambitious new filling mechanism.   Yes, one of my pens had problems, but there’s no reason to think that’s the manufacturer’s fault in this specific case.   My initial reservations about the back-heavy balance of the pen in-hand also gave way to general satisfaction with the long-term writing experience. Beyond that, there are some definite advantages to the vacuum filler for travel, due to its high ink capacity.

If you have smaller hands and the filling mechanism isn’t a must-have for you, I’d probably suggest opting for the lighter and better-balanced PenBBS 309 piston filler or a 308.  The latter can be eyedropper-filled for an extremely large ink capacity (although nib swaps can pose problems).

None of that is to detract from the accomplishment represented by this fountain pen model however!  At a time when Chinese pen makers are still infamous for producing knockoffs, PenBBS has created something that feels truly original.  They’re part of a new breed of Chinese fountain pen makers that are doing exciting things to shake up the pen market.  I think that’s something we should all aim to support.

Key Stats:

  • 29.7g overall, 19.1g uncapped
    • Compare to the PenBBS 308 at 20.3g/12.1g
  • Ink capacity: 2.1 mL
  • Length (metric):  145 mm capped, 130 mm uncapped, 160 mm with cap posted
  • Length (imperial): 5.7″ capped, 5.1″ uncapped, 6.3″ with cap posted

One thought on “PenBBS 456 Vacuum Filler Review

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