Opus 88 -- Eye-catching Eyedroppers!

Have you ever tried an eyedropper filled pen?  I learned how to use one a couple years ago for an earlier version of this article, but I don't own one myself, and we recently got a lot of additional cool Opus 88 models in the store, so I decided it was time to review!  I had forgotten how fun these pens are to use, and, to make it even more fun, I decided to bring an Opus 88 Mini with me on my five day adventure to Chicago.  One of the advantages of a pen with a shut-off valve like the Opus 88 is that it will keep your pen from leaking in flight if it is exposed to changes in air pressure.  I wanted to put it to the test, and also take advantage of the pen's large ink capacity.  I hadn't been on an airplane trip since before the pandemic, and I thought I might have a lot to write about!

[Pictured:  Opus 88 Mini in Savannah Zebra.]

 

Eyeing the Eyedroppers

What is an "eyedropper pen," anyway? To put it simply, an eyedropper filled fountain pen, or "eyedropper" for short, is a pen whose entire barrel serves as its ink reservoir.  There is no cartridge, cartridge-converter, or sac.  You don't use a piston, lever, or vacuum -filling mechanism to get the ink into the pen.  Filling the pen is very straightforward.  You unscrew the pen's front section and fill the body of the pen directly, using an eyedropper or a blunt syringe to transfer ink from a bottle into your pen.

The advantage of this type of pen is that it can hold a lot more ink; however, it's very important that the eyedropper pen be made correctly, have no holes or cracks in the body, and have a watertight seal between the barrel and grip section. Many eyedroppers are pens that the user has modified from a plastic cartridge/converter style pen (such as a Kaweco Sport or Platinum Preppy) by applying silicone grease to the threads, and, occasionally, adding an o-ring.  If you want to make your own eyedropper, be sure to choose an appropriate pen, and to make sure there are no metal components inside that could corrode.  "Eyedroppering" your pen can be really cool, but it's also risky!  If the pen isn't sealed correctly, you'll have a huge mess on your hands (and on anything else that comes in contact with your leaky pen!).

The earliest fountain pens, introduced in the late 1800s, were primarily dropper fillers, but self fillers were widely adopted by 1915 and had almost completely replaced commercial eyedropper filled pens by the 1920s. Eyedropper filled pens are pretty uncommon today, although they are still appreciated for their simplicity and the partnership that develops between user and pen. Some of the Victorian-era examples that you can find at pen shows are beautifully ornate and feature wonderfully flexible nibs, but they require a little more patience and intentionality to use than modern pens do.

If you want to experience a very user-friendly eyedropper, the Opus 88 fountain pens from Taiwan were designed as modern eyedroppers right from the start, with lots of clever design features that prevent blobs and leaks, and keep your pen running smoothly.  They are simple and fun to use, and are great writers as well, with interchangeable Jowo nibs made in Germany. I'll walk you through how to fill them and use their special features, then discuss all the different models later in the article.

 

First Impressions

My very first experience with an Opus 88 was when my friend Leila let me try her Demo Sapphire while we were planning an episode of our YouTube show, For Your Penjoyment.  She'd inked it with Diamine Enchanted Ocean, a gorgeous dark teal-leaning blue with lots of shading and silver shimmer.  Leila is a superb ink/pen matcher, and this combination was no exception.

The Demo model felt a little large and chunky in my hand at first, but it's fairly lightweight and very well-balanced, so I soon got pretty comfortable.  Although I wasn't immediately sure how I felt about the shape, my first impression was that using the Opus 88 was fun.  There was just something about the pen that felt playful and made me fond of it.  Leila's broad nib was very smooth, and squeaked a little as I wrote, a sensation that made me laugh.  Leila told me the squeak goes away after you break it in, then added, "I've been writing with this all weekend, and it's been a dream." 

She went on to tell me that she got her first two Opus 88 pens about a year before, so, with her two new pens, she now owned four.  The Opus 88 was her first eyedropper, and learning to fill it was no more scary than figuring out how to use a piston-filler for the first time.  She confided, "I favor it a little more [than a piston-filler]... it's much easier to clean. Like, by far. And, it's not like disassembling a TWSBI."  She noted that, for her, taking apart a TWSBI "can be fun," but "isn't practical in the same way" that rinsing out an Opus 88 is.

The ink capacity in the Opus 88 Demo is huge--3.5 ml--which is more than even the largest TWSBI (the Vac 700R has a maximum ink capacity of around 2.3ml), and more than you get in many commercially available ink samples.  This seems to me like a lot of ink to put in your pen at one time, but Leila told me she loves that about it.  "Because I'm so matchy-matchy [with my pens and inks], I tend to stick with one ink for a pen, so having that capacity makes life easier. There's nothing more frustrating than finding your creative flow and then your pen suddenly runs out of ink. I worry less with my Opus 88."  I don't write as much with my pens as Leila does, but that does sound like a big advantage if you're a prolific writer and stick to the same ink for a long time!

Leila's four ink picks for her Opus 88s were all shimmer inks, and, when I expressed surprise, she said, yes, all her Opus 88 pens have Broad nibs, and two have clear barrels.  She likes being able to see the pretty ink and the shimmer distribution through the barrels. Makes sense!  Although demonstrator pens don't usually appeal to me, I, too, liked being able to see inside the pens, especially because there aren't extra parts like converters or cartridges blocking your view of the beautiful ink sloshing around in the barrel.

I also talked with one of my favorite customers, Mikele, who bought the Demo Sapphire in Extra Fine and loved it.  She tested a Broad, but personally preferred the feeling of the Fine and Extra Fine nibs.  Mikele told me, "The Extra Fine feels surprisingly as crisp as the Kakuno!"  She brought her pen to the store so I could try the nib myself, and I was amazed by how smooth but precise it is. What a beautiful writer! Mikele, like Leila, said, "the eyedropper experience is great."  Although using an eyedropper pen seems very different at first, getting to know it is a quick and easy experience.

[Pictured:  Opus 88 Demo in Clear.]

 

The Eyedropper Experience

Opus 88's pens are Japanese style eyedropper fillers, so they are a little more sophisticated than the Victorian era kind or the kind you can make yourself.  They feature an internal ebonite rod that is attached to a blind cap at the end of the pen, which seals the feed when closed, preventing leaks, and keeps the ink flowing evenly when opened.  This is the same construction used in Pilot's huge Namiki Emperor luxury pens, but, of course, Opus 88 pens are only around a hundred dollars, not thousands like an Emperor!

Leila wanted me to see for myself how simple using an Opus 88 is, so she loaned me her brand-new Demo Green pen and matching Diamine Tropical Glow ink, trusting I'd figure it out.  She didn't instruct me on how to fill it, but I watched one video on YouTube, then jumped right in.  I am not a tinkerer, and I never take apart my TWSBI Diamond Mini, but this was fun! Instead of being scary, it felt like I was playing with a toy.  

The process is really simple:

1) Disassemble the pen by removing the cap and then unscrewing the grip section from the barrel.  It can feel a little hard to turn at first, compared to your cartridge-converter pens, but, remember, the pen needs a tight seal so it won't leak. It will probably squeak, and feel a little boingy from the little black rubber o-ring gasket.

2) Open the shut-off valve by loosening the blind cap at the bottom of the pen.  (Opus 88 calls this part of the pen the "bottom tail"!) Again, it will be a little hard to turn, but don't be afraid--you won't break it!  Keep unscrewing, and use a little elbow grease to pull it out so there's a gap between the threaded part and the barrel of the pen. You'll see the black plunger rod inside that connects to an ebonite piston and rubber gasket that seals the feed off from the barrel when fully depressed.

3) Fill the barrel with ink by using the eyedropper provided in your box to suck up ink from a bottle and release it directly into the open barrel of your pen.  You can also use a blunt syringe for this step if you want a little more control.  (Note that, in addition to giving you a nice glass eyedropper, Opus 88 also includes a spare o-ring!) I really liked Opus 88's glass eyedropper, because it's easy to disassemble the rubber bulb from the tube and rinse the whole thing clean.

I also thought it was cool that the Demo model's flat bottom serves a practical purpose during this step!  The pen is capable of standing up on its own and is quite stable, as long as you don't accidentally knock it over.  This is very handy, since you don't even need to hold it if you want to use both hands to control your syringe. Remember, the barrel holds a lot of ink, so you'll need multiple eyedroppers full if you want to fill it up all the way.

4) Set aside your inky eyedropper or syringe, and, holding the pen with the open end up, screw the grip section back onto the barrel.  Make sure it's fully closed, nice and tight.

5) Now, with the nib facing downward, screw the shut-off valve closed.  This will prime the feed for you. My ink didn't reach the nib right away, so I stood the pen on its "head" (cap down) for a few minutes to allow the ink to flow downward.  If you don't have a model with a flat top, just put the pen cap-down in an empty cup.  In less than five minutes, the pen is ready to write!

You can also prime the feed when the pen has been sitting for a while, to get the ink flowing.  All you have to do is unscrew the blind cap, pull the piston outward, and push it slowly back in.  Don't be afraid to pull it out far!  This is an especially great trick to have up your sleeve if you're using shimmer ink, which can settle and clog pens.  Just use the plunger to expel a drop of ink onto a piece of paper or cloth, and the pen will start writing perfectly again.

I really enjoyed the process of filling the Demo, and how hands-on and straightforward it was.  It made me feel in touch with the pen, sort of like the nice feeling of planting a plant with your hands in the dirt.  Instead of seeming intimidating, the experience felt friendly and easy-going, and I felt like I was playing rather than working to fill it.  The simple parts, and joyful, quirky color combinations in many of the pens add to the charming toy-like feel. All the pens have their own personalities.

When I filled the Mini to get ready for my Chicago trip, I felt the same way.  Following my Past Self's instructions was fun, worked perfectly, and was very satisfying.  (I even made a video of the process, if you want to see!) It also wasn't messy at all.  I got less ink on my hands than I usually do when using a converter or piston-filled pen!  Yes, I had to find somewhere to rest the inky eyedropper, and I needed to rinse it out after I filled the pen, so it's not something that's as easy to do away from home, but the pens hold so much ink, you don't need to refill them very often.  They really aren't impractical or hard to use at all.

There's one more important thing you need to know about the Opus 88's mechanism.  Similar to a vac filler like the Pilot Custom 823, its shut-off valve needs to be open in order for the ink to keep flowing, so unscrew the end cap a little bit and create a small gap if you're going to be using the pen for more than a few quick notes.  Unscrewing it so you can see all the threads but not the black rod is a good amount.

When you're done writing, screw the end cap closed again, and this will seal off the feed and stop air flow.  You can carry the pen without any worries about it "burping" ink.  This mechanism also will keep your pen from leaking if you fly with it and it is exposed to changes in air pressure.  With the shut-off valve closed, the ink will run dry after a short time, and no more ink will flow between the barrel and the nib.

I used Leila's green pen to take stream-of-consciousness notes on my immediate Opus 88 experience, then closed it back up to store when I was done.  On page two, I wrote, "Sort of irresistible."

 

Opus 88 Model Overview

We now carry four Opus 88 models:  the Demo, Jazz, Harmony, and Mini.  Both Jazz and Demo are oversized pens, great for people with large hands, while the graceful Harmony is a little smaller but still fairly large, similar in size to an Esterbrook Estie or Pilot Custom 823, but larger than a Sailor 1911L.  The cute Mini is shorter but quite chubby, and reaches the size of a full-sized pen when the cap is posted.

[Pictured, front to back:  Demo, Jazz, Harmony, and Mini models.]

All except the Mini use Opus 88's #12 nib, a #6 size Jowo nib.  Mini, to keep things proportional and allow for a smaller cap, uses Opus 88's #10 nib, a #5 size Jowo nib.  Both nibs are also available separately if you want to change your writing tip, and the nibs come in Extra Fine, Fine, Medium, Broad, and stub (1.4 mm for the minis, and 1.5 mm for the larger ones). The Demo model is even available with Fine Flex and Extra Fine Flex nib options! 

All four models work the same way, but each has a different aesthetic, so you can choose the one that most appeals to your sense of style.

[Pictured, left to right:  Demo, Jazz, Harmony, and Mini models.]

Here's a table I made to compare their specs.  For ink capacity comparison, Pilot's high-capacity vacuum filling model, Custom 823, holds about 2.55 ml of ink, while TWSBI's Diamond Mini holds about 1.3 ml, Eco about 1.75 ml, Diamond 580 about 1.8 ml, and Vac 700R about 2.3ml. The largest Pelikan, M1000, has a 1.60 ml ink capacity, and most cartridges hold between 0.7 and 1.2 ml.  I found a lot of inconsistent numbers for the Opus 88s' ink capacity, so I measured every model myself using a blunt syringe, just to check.

Pen Model	Length Capped	Length Uncapped	Length Posted	Maximum Diameter	Grip Diameter	Pen Weight	Weight Uncapped	Ink Capacity
Demo	14.7cm / 5.8"	13.7cm / 5.4"	n/a	16.5mm	11.7mm	0.96oz / 27g	0.60oz / 17g	3.5ml
Jazz	15.0cm / 5.9"	13.3cm / 5.2"	17.4cm / 6.9"	17.3mm	11.2mm	0.98oz / 28g	0.55oz / 16g	3.0ml
Harmony	14.0cm / 5.5"	12.9cm / 5.1"	17.0cm / 6.7"	15.7mm	10.6mm	0.86oz / 24g	0.47oz / 13g	2.2ml
Mini	11.9cm / 4.68"	10.9cm / 4.29"	14.0cm / 5.51"	15.0mm	10.0mm	0.80oz / 23g	0.49oz / 14g	1.9ml

 

The Demo

The Demo model has a lovable and chunky blunt shape, and, although it's smaller and shorter than Jazz with the cap on, it actually has the largest ink capacity and thickest grip section.  It comes in lots of fun variations (right now we have seven!), most of which are colorful and translucent, but a few actually have opaque barrels, contrary to the Demo name.  Demo's cap cannot be posted.  

I especially love the interesting colorblocking on the Color of the Year models!  Included in the picture above are 2021 in soft Ultimate Gray + translucent Illuminating Yellow, 2022 in Very Peri (a translucent periwinkle purple with opaque matte terracotta red ebonite grip section and finials), and the calm 2025 in opaque Mocha Mousse with translucent coffee colored accents. The 2024 pen (second from front) is a lovely jewel-like Green with a warm translucent olive grip section, a delightful departure from Pantone's Peach Fuzz choice.

Even more striking is the Sapphire (pictured below), a swirling mix of deep shimmering blues, accented by clear translucent blue finials. It simultaneously reminds me of the Earth from space, a galaxy, and the ocean.  This pen is a great choice if you prefer opaque barrels.

The Clear Demo, beautiful in its pure simplicity, is always a favorite because it goes with everything and is perfect for showing off your ink.

For a really fun and joyful pen, choose the confetti-esque Demo Color, which feels like your own little party.

There have also been wonderful and very special ocean-themed limited edition Demos in Sea Turtle, Dolphin, and Blue Whale. Those sell out quickly, but we do have a few Blue Whale pens right now!  I love how the realistically depicted ocean creatures are combined with an abstract geometric representation of the sea.

 

The Jazz

The Jazz model is a torpedo shaped pen, and we only have two versions right now: Clear Demo and Holiday, which is also a clear demonstrator pen!  Holiday has a frosted matte finish with gunmetal grey trim, while the regular Clear Demo's acrylic resin has a more shiny clear finish, with rhodium-plated silver colored trim.  They don't look dramatically different, but the finish does feel different!

[Pictured:  Holiday Jazz on top, with Clear Demo Jazz below.]

Although both the Jazz and Demo models offer clear demonstrator pens, Jazz's torpedo shape looks a little more classic, while Demo is slightly more contemporary.  They are both great pens.

[Pictured:  torpedo-shaped Jazz model on top vs. blunt-ended Demo model on bottom.]

The Jazz is a pretty large pen, but it's well-balanced and lightweight but solid feeling, so it feels good in my hand, not awkward.  The classic torpedo shape is handsome and looks professional, and the clear barrel shows off whatever beautiful ink you choose.

[Pictured:  Jazz model in my medium-sized woman's hand.]

I wouldn't post Jazz's cap, because it makes a very long pen, but you can if you really want to!

The Harmony

The Harmony is a slimmer, graceful model with a beautiful undulating clip and rose gold accents.  Its size, comparable to an Esterbrook Estie or Pilot Custom 823, feels great in my hand.  The cap posts securely, and I also like it with the cap set aside.

[Pictured:  The Harmony in Flower, in my medium-sized woman's hand.]

The two new colors that I brought home for this article, Flower and Cloud Dancer, are both very pretty, with a slightly translucent acrylic that captures the light but offers only a glimpse of their inner workings without actually being see-through.

Cloud Dancer, in particular, is stunning in person.  Opus 88 says, "This variant is turned from a premium, multi-tonal resin featuring wisps of opaque white, translucent grey, and soft blue. Each pen is unique, with the swirls dancing across the barrel like a time-lapse of a shifting sky."  How lovely!  To me, the pen comes across as an ethereal pale green, and its enchanting opalescence is impossible to capture in a still photo.

 

The Mini

I chose the Mini to fill with ink and bring on my Chicago trip because it's new to me, it's cute, and I like the smaller size!  It's a great alternative if you want to try an Opus 88 but find the other pens too large.  The price is also quite a bit lower than the other pens, which is nice.

I ended up being so busy (as usual when I go on vacation!) that I actually didn't do much writing, but I did have fun using the Mini.  The size feels great in my hand, the cap posts securely, and I didn't have any trouble remembering to unscrew the shut-off valve when I wanted to use the pen.  I've read that earlier versions of the Mini didn't post securely, but the current models definitely do, even with the shut-off valve unscrewed to expose all the threads.  The chunky shape isn't as compact as most pocket pens, but its thicker grip section is more comfortable for long writing sessions, and its ink capacity blows most pocket pens out of the water.  It also didn't leak even one drop on my flight to Chicago, or at any time during the trip.

We have the Mini in three wild color-printed designs, Bengal Tiger, Mara Leopard, and Savannah Zebra, each framed by solid black acrylic finials and polished chrome trim.  They are playful pens, but feel very solid in your hand, like a serious and sturdy writing instrument, not a toy or a cheap pen meant for children.  Even though it's a smaller pen, the Mini is actually heavier than the Harmony.  If I owned a Harmony and a Mini, I'd use the Harmony with the cap set aside (because I like the length without it), but post the cap on the Mini, making the Mini considerably heavier.  Both pens are well balanced and comfortable for me to write with, but, if you have strong preferences leaning toward heavier or lighter pens, take that into consideration.

The nibs on the larger pens feel a little nicer, but I actually really like the way the Mini writes, and I enjoyed drawing with it in the near-dark for entertainment on my late night plane ride home.  The nib is stiff, but has a little bit of play, and is a smooth, crisp, consistent writer.  I used a Fine, my usual favorite nib size.

Animal print patterns aren't really my thing, but these pens' cuteness factor is a big part of the appeal to a lot of people, and they are very charming and fun to collect.  I actually really enjoyed the crisp black and white stripes of the Zebra I chose, and it made me smile every time I took it out of my pen case.  Although I don't normally go for cute things, overall, I was a fan of the Mini!  I also loved our new store exclusive Quoth the Raven ink by Dominant Industry.  It was my first time trying a Dominant Industry ink, and the dark teal color and behavior were both excellent.

Revisiting this article reminded me how enjoyable and satisfying the process of filling and using eyedropper pens really is, and I love that we are now carrying so many more Opus 88 models, allowing a delightful amount of variety.  I would have no hesitation recommending an Opus 88, and I think adding one to your collection is the perfect way to bring some spark to your pen journey and make you fall in love all over again with the joy and uniqueness of fountain pens.

This is a company that still seems somewhat novel, but has stood the test of time.  Opus 88's founder, Michael Hsu, has personally and painstakingly created each pen to exacting standards for over two decades, and has earned a reputation for excellence as an OEM (Original Equipment Manufacturer) and ODM (Original Design Manufacturer) supplier since 1988.  I am excited to see what new models and colorways Opus 88 will release next.  As for me, I keep reaching for that Mini.  The shape, the size, and the ritual of filling it and opening and closing the end cap are something I didn't know would be so irresistible and satisfying.  I'm not sure I'm an animal print kind of person, but I'll keep my eye out for a "Laura" style model down the road...

-Laura P.

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