Posts filed under Fountain Pens

ensso Bolt Fountain Pen Review

ennso Bolt Fountain Pen Review

(Jeff Abbott is a regular contributor at The Pen Addict. You can find more from Jeff online at Draft Evolution and Twitter.)

The idea of a retractable fountain pen is something of a white whale. There are very few options, and it seems every one of these options comes with some serious trade-offs. For something that seems like such a big design challenge, that doesn't stop people from trying. It's also not often that we see new options come onto the scene in this category, so that's why I'm excited to talk about the Bolt from ensso.

On the outside, the Bolt looks like another machined metal pen that uses a simple bolt mechanism to control the retractable refill. The all titanium body is lightweight and feels great in the hand, but it's really surprising to extend the refill and see a slim fountain pen nib emerge from the end of the cone.

ennso Bolt Fountain Pen

At just 5.16 inches (13.2 cm), the Bolt is a really comfortable size both in hand and when storing. The barrel diameter is fairly slim at just 3/8" (9.5mm), similar to most gel pen barrels and a little slimmer than most fountain pens.

ennso Bolt Fountain Pen tip

In most cases, there are two Achilles heels when designing a retractable fountain pen: clip placement and sealing the nib when not in use. There are other challenges when designing a pen like this, but these two seem to be obvious factors with the products we have access to today. The way we hold a pen when writing is unique to each individual. For a pen like the Pilot Vanishing Point or Decimo, the clip placement might make the pen uncomfortable for many people. If you can't accommodate the clip being part of your grip pattern, then it just doesn't work for you.

ennso Bolt Fountain Pen twist

With the Bolt, the clip is an optional accessory that installs on the back of the pen barrel. The unit I have for testing didn't come with the clip, but it's easy to install by using a coin to remove the plain end and screw on the clip end. When using the clip to store the pen upright, this does face the nib toward the ground. I thought that might be an issue since gravity and motion might cause some ink to leak out and stain whatever it's clipped to.

I tried this out by simply carrying the pen around in a pocket with the point faced down. In my testing with normal walking, no ink escaped from the pen, and the nib was clean when I got it out to write. My assumption is that some leakage could still occur depending on the environment and the level of movement you put the pen through. I would certainly be careful about flying with this pen due to the large air pressure change. Either empty the pen before flying or isolate it in a bag to prevent some inky mishaps in your luggage. Overall, though, I really appreciate the clip placement on the Bolt, and I like the optional nature of the clip even more. Even though I don't have a clip to try out, I still think I prefer this pen sans clip. It's more sleek and the bolt mechanism acts as a great stopper to keep the pen from rolling around on flat surfaces when not in use.

Similarly, a fountain pen isn't much use if the tip dries out after a couple of hours while retracted due to a bad seal that lets too much moisture leave the nib and feed. This seems to be the really tricky bit to design and manufacture at scale. Pilot seems to have a good solution, as does Platinum.

ennso Bolt Fountain Pen tip

With the Bolt, I've been incredibly impressed by how well their seal design works. According to their webpage, they spent over a year developing and testing this system, and it's really simple in practice. It's just a small piece of silicone that has a couple of slits that form an X pattern that allow the nib to pass through, but come back together to form a seal over the nib when it's retracted. I've left this pen alone for over a month and come back to use it only to find that it writes almost immediately. Very nice. Also, ensso includes two extra silicone seals with the pen in case the original one (or second) fails. Time will tell how these hold up.

ennso Bolt Fountain Pen tip

One of the concerns I had when looking at this silicone sleeve mechanism is that the contact with the nib and the silicone might cause excessive ink creep on the nib. By ink creep, I mean how ink tends to leak a tiny bit around the slit on the top side of the nib. And if you try to use a paper towel to clean up a tiny dot of ink, you end up dragging a lot more ink onto the nib due to the capillary action of the towel when it hits the slit. I'm happy to report that this just isn't an issue with the Bolt. There hasn't been any ink creep on this nib at all.

ennso Bolt Fountain Pen disassembled

And while talking about the nib, let's just take a minute to admire this custom nib unit that ensso designed. It's reminiscent of the nib units you see in Pilot's offerings, but this one uses a standard international cartridge converter to supply ink. The actual nib and feed are super small — they're like miniatures.

I've really enjoyed using the Bolt over the past couple months. It's a solid performer that has really impressed me and removed any doubts I had about the performance of the retractable nib design. Operating the bolt mechanism is really easy to do one handed, and I really like the amount of resistance the spring provides. I also love how the nib retracts a bit slower than you expect due to the drag of the silicone on the nib unit. It's similar to watching a soft-close drawer finish closing. Satisfying.

ennso Bolt Fountain Pen comparison

The only nitpick I have for this pen is about the feel of the bolt mechanism. It works well, but I don't love the metal-on-metal feel/sound when operating it. This is likely unavoidable since all the parts are metal, but I wonder if a small synthetic bushing would help smooth out the feel and get rid of the minor nails-on-a-chalkboard sound of metal grinding against metal. Or maybe a little dab of carefully applied silicone grease would alleviate that problem. Either way, it's a minor gripe on an otherwise stellar pen.

ennso Bolt Fountain Pen converter

The Bolt is only available in the titanium finish, but you have an option of EF, F, or M nibs (and you can pick up several), along with the option of a clip. The clip is an additional $25 on top of the standard $120 price for the pen. You can pre-order the pen now and expect delivery later this month. If you like retractable fountain pens and like the aesthetic of this pen, you should go for it. It's a solid performer at a great price, and it will hold up to years of use thanks to the titanium material and the extra silicone seals that ensso provide with the pen.

(Brad purchased this pen via the enso Bolt Kickstarter campaign.)


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ennso Bolt Fountain Pen writing
Posted on April 2, 2025 and filed under Ensso, Fountain Pens, Pen Reviews.

Diplomat Viper Fountain Pen Review

(The is a guest post from Paul, aka The Poor Penman. Paul (he/him) is a life-long stationery fiend and former industry professional. Read about his journey with pens and paper at The Poor Penman and on Instagram.)

The Viper is the latest in a long line of boldly-designed fountain pens from Diplomat, a brand with over 100-years of experience under their belt. In addition to manufacturing fountain pens, they are credited with being one of the first ballpoint pen manufacturers in Germany. They also introduced their region to ink cartridges, which were far easier to use than the filling mechanisms of the era.

Diplomat Viper Fountain Pen Review

The exterior of the pen is adorned with engraved “scales” in a diamond pattern which give it the serpentine signifier. The pattern, while a bit too geometrically-perfect to be found in nature, gives the pen a striking look. The Viper uses a snappy magnetic slip-cap that glides off and on with just the right amount of resistance. It can also be posted, though the magnetism does not extend to the rear. The pen’s clip is a slim and firm bar that offers security without imposing on the overall design aesthetic. It is also surprisingly rigid, often pushing and tugging at fabric or elastic retainers rather than gliding over them. This can make rapid re-sleeving a bit of an issue, but at least security is never in question. On-pen branding is minimal, with “Diplomat” stamped twice around the cap ring, and their logo stamped on the finial.

Diplomat Viper Fountain Pen

Beneath the cap, protruding like a singular fang, is the Viper’s most unique feature: a hooded nib. The nib is available in exactly one (1) width: Fine-Medium. The nib appears to be roughly the size of a Jowo #6, though it is narrower as it recedes into the housing. If there is a way to take this unit apart to get a better look at the nib, I have not yet found it.

Diplomat Viper Fountain Pen Nib
Diplomat Viper Nib

True to the vague sizing, this pen lays down a line somewhere between a western Fine and Medium; roughly equivalent to a 0.5 to 0.7 mm gel pen. Line width can vary a bit with your choice of paper and ink, but in my observations it lands a little closer to standard Fine nibs. There is also a fair amount of tipping material on the nib. If custom grinds are your thing, the Viper is a great candidate. Ink flow is good as well. Not overly wet, but rich enough to lay down a solid line.

Diplomat Viper Fountain Pen Line

I’m a big fan of the diamond scale pattern on the cap and barrel. This design gives an otherwise typical pen a unique look, an interesting tactile feel. The surface grooves are big enough to feel when you run your finger over the surface, but not so deep as to catch or drag.

Diplomat Viper Fountain Pen Barrel

Writing with this pen feels good. The writing experience might not blow your socks off, but if you’re looking for solid, consistent performance, you won't be disappointed. The grip section gradually slopes towards the front, and feels like it was designed more for aesthetics than ergonomics. I typically prefer a bit of contour in my pen grips, but the Viper smoothly slopes from around 11 mm at the thickest point to around 8.5 mm at the thinnest graspable area in a flat curve. For comparison the Pentel EnerGel’s grip has a diameter of 10.5 mm, and the TWSBI ECO measures in at around 9.5 mm.

Diplomat Viper Fountain Pen Converter

Inking a pen with a hooded nib may be cause for consternation. When filling through traditional methods (dunking the nib into your ink of choice and turning the converter’s plunger,) you end up with ink on roughly a quarter-inch of the grip section that needs to be cleaned. There are also some nooks and crannies above the nib where excess ink can hide, waiting to leave a little surprise on your page later. Rather than deal with cleaning the nib and grip, I typically fill my converter pens by dipping the converter directly into the ink bottle, then plugging the converter into the pen after wiping off the comparably smaller amount of ink from the device. You do have to wait a few minutes for the ink to find its way through the feed, and it usually results in some lightly-inked fingers, but I vastly prefer this method over submerging the nib.

On a side note, upon researching the pen it appears that I did not receive the stock/factory converter with my Viper. (Pen show pick-up, these things happen.) My pen came with what I’ll call a Manuscript-style converter as there is no obvious branding. I vastly prefer this style for their ease of disassembly when it comes time to clean. The pen should work fine with any Standard International converter, so don’t be surprised if you buy the Viper and it comes with something different from what I’m showing you here today.

Fountain Pen Converter

The Viper is one of those pens I’ve been eyeing since its release in late-2024. When I saw it at the California Pen Show (in the Year of the Snake, no less) I simply could not go home without it. This pen is a solid writer, and adds a very unique layer of style to any collection. While Diplomat have been hard at work updating the Viper with two additional color variants (blue and brown) as well as a rollerball version, they have not yet seen fit to add more nib options to the mix. While I was able to score a slight discount on the last day of the pen show, I don’t have any trouble recommending this pen at its typical retail price of $96. If you’re looking for a solid writer with a unique flair, check out the Diplomat Viper at Truphae Inc., or your retailer of choice.

Diplomat Viper Fountain Pen Holder

Special thanks to Truphae Inc. for making me an offer I couldn’t refuse, and to The Pen Addict for platforming this review!


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Diplomat Viper Fountain Pen Cap
Posted on March 31, 2025 and filed under Diplomat, Fountain Pens, Pen Reviews.

Opus 88 Mini Pocket Stripes Fountain Pen Review

Opus 88 Mini Pocket Stripes Fountain Pen Review

(Jeff Abbott is a regular contributor at The Pen Addict. You can find more from Jeff online at Draft Evolution and Twitter.)

No matter how many fountain pens I accumulate, I'll have a soft spot for pocket fountain pens. They're under-represented in the grand scheme, and they're just so cute and utilitarian by nature. Normally, a pocket pen means you also have a smaller ink capacity, but that's not the case at all with the Opus 88 Mini.

The colorway I have is called Stripes, and I love the mixture of blues, greens, purples, and pinks that they incorporate into the materials. The pen is just 4.5 inches (11.8 cm) long when closed, and just 0.6 inches (15.4 mm) in diameter. Despite being so short, the diameter is actually a bit larger compared to other pocket pens I've used in the past. It's the same diameter and shape as a standard-size pen, which means it's really comfortable to hold.

Opus 88 Mini Pocket Stripes Fountain Pen

Uncapped, the pen is 4.25 inches (10.8 cm) long, and 5.5 inches (14 cm) when the cap is posted. The posted length is pretty much the same as a closed standard-size pen.

The best part about these dimensions (particularly the diameter) is how they translate to ink capacity. Like other Opus 88 pens, this one is also an eyedropper design, meaning it holds an astonishing amount of ink for its size. Holding between 2-3 ml of ink, this puts cartridge-converters to shame. Filling and cleaning is a simple task, and you also get the added security of the ink reservoir being shut off from the feed when the pen is closed.

Opus 88 Mini Pocket Stripes Fountain Pen Nib

The Mini uses a #5 Jowo steel nib, which fits the small nature of the pen quite well. Plus, the small nib allows the cap to be just a bit smaller as well. The fine nib in my unit works perfectly out of the box, and I've been really happen with how it writes. The nib is stiff and produces crisp line edges while still feeling smooth and consistent while writing. The feed does a great job of supplying the ink to the end of the nib. There's not much flex to this nib, but you can tease out a little line variation if you practice putting pressure on the nib while making downstroke marks.

Opus 88 Mini Pocket Stripes Fountain Pen Barrel

Going back to the materials and colors of the pen body and cap, I'm still so happy with my choice of the Stripes colorway. The body of the pen is fair simple — the blind cap and grip section are both polished black acrylic, but the body is made of a translucent blue/turquoise acrylic material that allows you to see the ink and inner workings of the pen along with the threads for the blind cap fitting. I love translucent colored materials, and this one is no exception. It's pure joy seeing ink slosh around in the body.

The cap also has a polished black finial, but the rest of the cap is made up of stripes of colors that go around the diameter of the pen. The sections aren't all the same size, which adds some visual interest and diversity. All of the colors they used in the cap are complimentary to the lovely aqua color of the body material.

To top off all the acrylic colors, the pen features silver trim that brings everything together. The clip is easy to use, but still stiff and strong enough to keep it secured to anything that fits in the opening.

Opus 88 Mini Pocket Stripes Fountain Pen Comparison

I've really enjoyed writing with this pen and carrying it around with me. It's not the smallest pocket pen, but it's still really cute and fun to handle. The grip section is a little on the small side for my fingers, but I get used to the size quickly once I write a couple of words. Overall, this pen is just another fantastic example of Opus 88 craftsmanship and aesthetics.

The Opus 88 Mini Stripes Pocket fountain pen is $79 and comes with your choice of EF, F, M, B, or 1.4mm italic steel nib. If the colors of the Stripes model aren't your jam, there are plenty of other options as well.

If you love the size of the Kaweco Sport but want a larger ink capacity, I think the Opus 88 Mini is a great option to think about. The pen is a solid performer with a massive ink reservoir, and the color options are super fun.

(Vanness Pens provided this product at a discount to The Pen Addict for review purposes.)


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Opus 88 Mini Pocket Stripes Fountain Pen Writing
Posted on March 19, 2025 and filed under Opus, Fountain Pens, Pen Reviews.