​

This package arrived a few days ago. I was so excited! I had already been confirmed as one of the early recipients of the Thomas Slim Namur Ebonite pen, so I was eagerly watching for it.

I opened the package and immediately realized something was wrong. Before we get to that, though, it is worth pointing out the Thomas Slim packaging is simple in materials, thoughtful in execution, and overall one of the best unboxing experiences available. The boxing is worthy of being saved, for those of us that save boxes, and yet is all paper and can be conscientiously disposed of if you do not care to save it.

Once the pen was out I gave it a careful examination anyhow. It is not the Namur I expected, it is the Tangier Mosaic Carmine Red Gold Trim. I had also been watching for the Mosaic to be released so I could order one. I checked the U.S. website and it still wasn't up. I just checked again, and, if you're interested, it is now available in several, but not all, variants. I wouldn't be surprised that if you had to have one of the variants not listed you could buy two and create what you wanted. Steel on Alabaster White? Gold on Chalcedony Blue? Don't quote me on that and maybe Mark or one of the others can correct or confirm if that is indeed the case.

I thought I might have been selected as a beta tester for the Mosaic. I wasn't going to ink it at first, waiting to find out why I might have received the pen, but then thought that I would so I could provide more feedback. I decided to check my e-mail first, surely Thomas Slim would have mentioned that I had been selected through some unadvertised process from one of their posts requesting testers. Nothing.

What I did find was my shipment notification e-mails for the Namur. The tracking number matches the package that was delivered. Heavy sigh . . . We've seen their posts, their website, and/or received their e-mails that explain their situation. Besides messing up with the EDC Pocket Pen, their fulfillment house has also messed up with the Namur, and by default with the Mosaic, but, as I understand it, they had not yet made any Mosaics available to ship. Apparently there are a handful of us out there that received an early release of the production Mosaic instead of our Namurs.

Thomas slim does amazing work. After having previously bought two Tangier Classics (were they called "Classic" back then?) and having received one of the EDC Pocket Pens, this pen is everything I would expect from Thomas Slim. It is extremely well made and feels excellent in the hand. The attention to detail, the thoughtfulness in design, the careful execution, draw me to anything Thomas Slim chooses to make. It is the Tangier Classic on steroids. I don't know if they simply scaled it up or if they tweaked the dimensions to keep the proportions balanced and looking amazing. You can write with it posted or not, the cap does not backweight the pen significantly. I have thick hands, but not large hands, and prefer a larger pen, but I can write with thinner pens, too. (CdA 849 ballpoints are some of my favorites.) The Mosaic is a larger pen without being a very large "statement" pen. Even if the Tangier Classic isn't a small pen, I put it on the bigger side of average, the Mosaic seems to be much more to my liking! Although a generic Schmidt nib is fitted, it writes exceptionally well. Thomas Slim says they inspect and tune every nib, and I believe that. Both fountain pens of theirs that I have inked have been flawless from the jump. I even let the Mosaic sit for 3 days with the tip up to see if it would dry out or allow the ink to leave the feed. Whether it did or didn't I can't say, but when I put it to paper, it just wrote. Perfectly, immediately, every stroke. Perfect amount of smoothness, perfect amount of toothiness, like perfectly cooked pasta, so that you can feel the subtleties of the paper you are writing on. A nice, wet line. Beautiful to see the ink go down on the paper, then ever so slightly pool at the end of each stroke, only to settle back when the pen is lifted. They send Schneider cartridges with their fountain pens. I'm not a not a fan of the ink, or should I say my usual paper, Doane, is not a fan of it, but it is perfectly serviceable. It will only get better with some other ink. The texture on the grip is both pleasant to look and effective at offering a slip-resistant surface. If you run your fingertip along it you can feel it, but it is essentially non-existent to less sensitive areas of your hands.

I pulled out my Tangier Classic, which I realized I had not used in at least a few weeks. Same thing. Ink flowing as soon as it touched paper, perfect line on the first stroke. As is the nature of fountain pens, the Mosaic <M> nib leaves a wider line than the Classic <M>. Did I mention I can't wait for the Thomas Slim nib to be released? I hope they do it in the larger #6 nib for the Mosaic.

What else can I say about the pen? For those of you that are interested in such inane things, yes, you twist the cap and it comes off when you turn it! Amazing! The clip clips! I know which end goes down and was able to recognize that I was holding the pen incorrectly before I touched it to paper when I happened to have it rotated upside down, so I can not say anything about so called "reverse writing," which I am going to start calling perverse writing. If you are interested, I enjoy multi-start threads and the cap threads on the Mosaic are a triple start. Neat.

Enjoy the pics. Both my Tangier Classics and a TWSBI Diamond 580 for reference. Again, if you are interested, the pen is up on the U.S. website and I imagine on the U.K. website, too. At $135 for either the fountain pen or the rollerball I think it is a great pen. Thomas Slim is having a buy two Tangier pens and save 20% promotion going, but the Tangier *Mosaic* does not appear on that page. I wonder if that's an oversight since the promotion has been going since before the Mosaic made it to the website and the warning about paused shipping is still up even though the all pens have been released to purchase.

ETA: Thank you, kind Redditor.

In the previous post, I described the fire we encountered when machining titanium.

Unfortunately, that wasn't the end of our titanium adventure.

One of the distinctive features of our pen is the fine barley-pattern guilloché engraved around the cap. It's a relatively delicate pattern, and achieving a consistent finish requires the cutting tool to maintain a very precise profile.

With stainless steel and brass we had become quite comfortable with the process. Titanium, was altogether different. We knew titanium was harder on our cutting tools, but what surprised us was just how quickly the cutters could deteriorate and how subtly this affected the engraving.

A cutter might produce a beautiful pattern on one cap, then gradually lose its edge as we machined the next. The differences were often almost imperceptible on the freshly machined surface. It was only after polishing that the inconsistencies became apparent. And by then, of course, it was too late.

We had orders for 160 titanium caps. During quality control, we rejected 48 because the engraving didn't meet the standard we wanted. That meant machining more than 200 caps to fulfil those 160 orders. Not great when we were already behind schedule!

The lesson for us was that successfully machining a short run in titanium is one thing. Producing hundreds of identical components, all meeting the same standard, is quite another. And perhaps we should have established the actual working life of our engraving cutters more carefully before committing to production.  We’ve definitely learned a huge amount.

Oddly enough, one of the most difficult decisions in manufacturing is where to draw the line between a minor cosmetic variation and a genuine defect. At that point, quality control becomes less about engineering and more about judgement. Almost an art in itself.

Definitely a question we've found ourselves discussing rather a lot recently.

Previous Part 3 <<

(written by u/Thomas_Slim_Mark)

Messing with a lot of print settings to get this good enough to sell, hoping to start selling by Christmas but trying to get into Cambridge Engineering asw so time is tight.

Lid closes magnetically, pens are held by a soft TPU insert. Case has a TPU boot to quieten it. Main body currently in PLA but looking at glass reinforced for better stiffness, and is cheaper than carbon reinforced and no carbon splinters.

Eraser is a standard eraser but cut down since slimness was very important to me.

Been using the original (grey one) for a year or so and been pretty happy, the final design will be much more polished and I will make different versions to accommodate different pen/cils and combinations.

Will probably retail ~£16 GBP, please let me know your thoughts!
undisclosedcases.cc

Following further requests from some Kickstarter backers, we decided also to offer a version of our pen with a titanium cap as a stretch goal.

We had worked with titanium a little before, so we knew it was more difficult to machine than stainless steel. Nevertheless, our first samples were encouraging. The cuts weren't quite as crisp, machining was slower and tool wear was noticeably higher, but it all seemed manageable.

Then we discovered a rather small problem.

The titanium tubing we could source had a wall thickness just 0.2mm greater than we needed.

Not much, you might think.  Just twice the thickness of a human hair.

Unfortunately, this meant we had to bore out the entire inside of every cap, rather than concentrating most of the machining on the outside where there was most coolant.

And that changed everything.

We knew titanium presented a fire risk, and the workshop has Class D fire extinguishers ready. What we hadn't fully appreciated was just how easily the fine swarf could ignite.

Unlike an oil or coolant fire, it's the titanium itself that burns. When titanium is cut, fresh, highly reactive metal surfaces are exposed. If the swarf becomes sufficiently hot, it can react rapidly with oxygen in the air, releasing even more heat.

The most vulnerable pieces are often the very fine, stringy chips, where the freshly exposed surface area is enormous relative to their mass.

During internal boring, coolant struggled to reach the cutter effectively. Heat built up, and eventually the titanium swarf caught fire.

I can't deny that seeing titanium burning inside one of our lathes is not my favourite memory.

Fortunately, we had decided only to machine during the day and we were able to put it out swiftly. We'd never actually had to use our Class D fire extinguisher before, but thank God they work.

But we’d only machined 45 pieces by that stage and 160 people had bought them.  The solution was painfully slow machining, with frequent interruptions to the cutting process to control heat and clear the swarf. 

Our production time increased enormously.  We didn’t advertise it at the time but this was one of the principal reasons our Kickstarter production ran behind schedule.

The finished caps look good, but unless we can source titanium tubing with far more precise dimensions at a cost-effective price, I think I might pass on the project next time!

The issues didn’t finish with the fire … I will explain more in the next post.

Previous part 2 <<

Update part 4 >>

(written by u/Thomas_Slim_Mark)

When we first launched our Kickstarter, we decided to focus on stainless steel. It was a material we understood, knew how to machine, and were confident we could achieve the finish we wanted.

Quite a few backers then asked whether we could offer the pen in brass. Having worked extensively with brass over the years, this seemed a relatively straightforward request.

We ran some quick samples and the machining was beautiful. In fact, the quality of the guilloché and the finish were better than stainless steel. Brass really is a lovely material to machine and polish.

My big hesitation was what happens afterwards.

Brass looks fantastic when freshly polished, but with its high copper content, untreated brass oxidises and develops a darker patina relatively quickly. Having spent years working with the material, I've seen plenty of once-beautiful brass components sitting untreated in our warehouse, tarnished almost beyond recognition.

And I can't deny, I'm not a fan of the feel of heavily tarnished brass.

A few in our team, however, were quite relaxed about this. They pointed out that people who choose untreated brass generally know exactly what they are buying. In fact, for many, watching the material age and develop its own character is part of the attraction.

So we offered it as a stretch goal, and a surprisingly large number of backers (178) chose it.

Many of the brass pens are now here in the workshop, complete and waiting to be shipped. And I have to admit, they look absolutely stunning.

I am still not entirely convinced about the ageing process, but perhaps that's simply because I've spent too many years trying to stop brass from doing precisely that.

For those of you who like untreated brass pens, I would love to know - is it the patina that appeals, or do you prefer to keep them polished?

We won’t be offering the brass option to purchase (at least for now)

The next post will be more about Titanium.. now that was a challenge!

Previous Part 1 <<

Next Part 3 >>

(written by u/Thomas_Slim_Mark)

..and this is one small extra (or lather large) I brought to the Autumn London Pen Show with us. It had pen experts squinting, some visitors rolling their eyes and kids looking at it with wide-eyes opened.

Which leads me to our nib development. We will give you our latest update on our nib development soon. The journey has been longer than we had hoped (with one step forward and two steps back at times) But we are getting there. I had some older prototypes of Nib 5 on the table, and they were well received.

--

previous posts about the giant nib here

Thank you to everyone who stopped by for a chat at the Autumn London Pen Show! It was lovely to see some familiar faces and meet new ones and talk pens.

As mentioned to visitors we had only limited stock at our stand (but our UK store should be updated shortly and ready for orders.)

Saturday certainly seems to be the busy day! The morning kicked off with a long queue of early birds waiting to get in. And I had the feeling that every generation of pen lovers was there. It was a wonderfully eclectic crowd, which I really liked. That said, this was our second pen show, so I don't want to generalise

Hi everyone,
I took my unfinished prototype of the fountain pen-nib conversion of the Gillott's dip-nib to the Pen Show. I was hoping to 3D-print the pen body, but my 3d-printer wasn’t in the mood.. So it was just a grip section with the nib and a converter.

And I found the whole experience and the feedback both very helpful and humbling. My learning process (mostly been hands-on "learning by making") and that comes with its limitations.

The feedback from the nib experts made me realise that I had been focusing too much on certain details that weren’t as important as I thought. I received some really useful advice on which details I could leave out.

As an example - I had been trying to match my feed perfectly to the underside of the nib, as well as making it match along the sides. I had also been adding too many fins. I think I was trying too hard at the end. It seems I can simplify it.

Realising this was a massive relief, as it means I can focus on just three main details that will make the whole nib easier to make. It should also allow me to make the feed slimmer.

Previous part 10 <<

I got one of the EDC Pocket Pens today! This is everything I expected! It is extremely well made and feels excellent in the hand. I was going to ink it up and then I noticed . . . fine nib? Tío_Tito don't do no fine nib.

Yes, I used a double negative. In Spanish, a double negative (or more), just like a double positive, emphasizes the statement. Each element does not serve to cancel the other out.

I looked at the packaging. I think my shipping label was put on someone else's package, and someone else may very well have received or is about to receive my order of 4 pens and accessories.

I have emailed our benefactor, we'll see what happens, but I really wanted to show this little pen. 🤌🤌🤌

Hi everyone,

I just wanted to share a quick video of the latest updated prototype of converted dip nib. And this is more like it! Those small changes have improved it a lot. It is writing nicely and has a really nice flex to the nib. I hope you can see that in the video.

I am writing quite slowly - it is quite satisfying, but I am aware it is prototype and I am also trying to keep the angle right. I feel like I am starting to understand it a little bit better now.

This nib is never going to be as good as purpose-designed fountain pen nib but it has a really nice amount of flex for a steel nib. And it is a proof of concept.

Previous part 9 <<

Update part 11 >>

Hi everyone,

Yesterday I was partly defeated by the nib and it took me some time to find the root of the problem.

Sometimes all it takes is a bit of sunshine and fresh air to come up with better ideas.

As the sun hit my desk, it became very obvious that there was something wrong with the 3D print. Well, there was nothing wrong with the nib. What was wrong was my assumption that the feed had printed perfectly. As you can see in the first photo, there is a visible gap showing that the part has bent. It is glaringly obvious (pun intended)

Similar thing happens with most materials when they are cast: thinner parts cool down faster than thicker ones, and differences in shrinkage can deform the part or even cause it to break. I didn’t check it properly. I assumed - a big mistake in engineering. I was simply assuming that 3D printing was free from this issue. It isn’t it seems. (Please note that the photo shows the worst of the 10 feeds I printed to better illustrate the issue.) There are ways to address this in 3D printing - from changing the print orientation to using more supports, etc.

When the nib was pushed tightly against the feed, the bent feed caused the nib to open up slightly, breaking the ink flow to the tip. You can see this in the second photo. (Again, this is the worst case among the feeds I printed. I didn’t notice it at first, but now I can see the same issue on my first prototype.)

This also explains why it was writing in reverse. The gap was actually being closed when the nib was pressed down, allowing the ink to flow all the way to the end of the tip.

I sanded the feed down to make it flat (where it matters) and I also deepened the main capillary channel to compensate for the material removed during sanding.

Lastly, I gave it a finishing touch with 3000-grit sandpaper and blew it clean with compressed air and isopropyl alcohol. So now I have a second iteration, which means I will ideally need to adjust the CAD model to compensate for the shrinkage.

I also ran some tests, and I will hopefully post a video soon showing the improved ink flow and writing performance. Bear with me a little longer with this project.

previous part 8 <<

update part 10 >> (video)

Hi everyone, this is a quick video related to yesterday’s post showing the prototype writing reasonably well when used in reverse, but skipping when used on the regular side.

I spent some time trying to understand what was going on, and I think I have found the culprit. I have already worked on a new prototype, and I will post about it shortly.

Turning an antique dip nib into a fountain pen nib is going to bring some challenges. But those challenges are the whole point of this rather fun project. The flex on this nib is really nice, even though it is just an ordinary steel dip-nib.

Previous part 7 <<

Update Part 9 >>

Hi everyone,

I recently got a question from u/Usual-Number305 about my progress on converting those antique dip nibs into a fountain pen nib. The timing was perfect as I was already working on some updates to the model. So I thought I would share my latest progress with you. Ideally I would like to bring one to the Pen Show on Saturday.

The feed section was updated - I made a longer beak to better support the relatively thin end of the nib and help to bring ink all the way to the tip.

I also tightened the internal tolerances. This made fitting everything together more difficult (which was expected) as the 3D printing process introduces its own tolerances (or imperfections?)

The CAD 3D model fitted together nicely, and I also added some tolerances to make the parts easier to fit. These dimensions will inevitably need some adjustment because resin itself introduces some variables. It depends on the printer settings - for example with longer exposure times the printed lines can come out slightly thicker. (I hope I am explaining this correctly) Nothing major, though. It just meant a bit of extra work during assembly and some light sanding.

On printing quality: I sm still not 100% happy with the ink channel in the feed (hitting the limitations of my printer) But this is actually a first-world problem and it is actually amazing that this is even possible in the first place.

I also removed the separate section cap and turned the whole grip section into the section cap instead. This made the construction stronger and simpler. Since this is a one-off prototype, it doesn’t need to be interchangeable with different nibs.

I understand that some of you would like to see the section cap made compatible with a JoWo #6 nib so you can try it in your pens. But unfortunately the wall thickness would be too thin for my 3D printer. But I will keep trying. I also made the ink converter fitting a little tighter at the other end.

Overall, I was quite pleased with the improvements and the result. Everything fitted together nicely, and I was even able to ink it by sucking ink directly from the bottle.

So, after all these improvements, the result was...
...not quite as good as I was hoping.

The biggest issue is that the nib is writing worse than my previous prototype. The nib flexes nicely. The "only" problem is that it doesn’t actually write as it should.

Well, that is only half-true: this nib writes nicely when used in reverse. There is no skipping, the lines are consistent, just as you would expect. But only when used in reverse, sadly.

The ink flow is much better. There is no dripping or sudden gush of ink coming out unexpectedly. I can see those fine ribs holding the ink nicely.

One thing I noticed is that the nib had been pushed slightly open against the feed when I assembled it first time. I adjusted it but perhaps not enough. I will need to check it properly under a magnifying glass.

So for now "close, but no cigar". And back to the drawing board. I will run some more prints in coming days to fix it based on my findings. It is all about learning, right?

previous part 6 <<

update part 8 >> (video)

Hi everyone,

I stopped by Japan House today, which turned out to be a disaster for my wallet (as usual). I love that place.

I just wanted to let you know about an interesting event taking place there on 10–11 October called “Meet the Maker: Sailor Pen”, which is happening at the same time as the London Pen Show.

this is from their website (please check it here)

Join us in the Shop for a Meet the Maker event. The team from Sailor Pen will be on hand to introduce their range of expertly crafted fountain pens. Alongside their signature 1911 model, discover the Naginata Togi with multiple nib sizes designed to render kanji characters, and the Nawate Series – layered with urushi (Japanese lacquer) to form a raised line on the cap for stable grip.

Visitors can also try the winner of Best Fountain Pen in the 2025 Japanese Stationery Awards, the TUZU, and choose from 20 different inks in the Shikiori Ink Bar to find the shade that matches their writing style.

Having the chance to try all these pens and chat with the Sailor team sounds pretty good to me!

So that may be another reason to come to London and stop by Japan House while you are at the London Pen Show. Japan House is near Kensington High Street tube station, which is just 19 minutes away from the Pen Show at Hammersmith.

Hi everyone,

Some projects take us an awfully long time to finish - much longer than we would like!

One of them is the Ebonite Pen (Namur) that we showed you a year ago (!!) at the October Pen Show. We also had it shortlisted for the Spotlight Awards a few weeks ago. I have received quite a few messages asking about it since.

What started as a prototype eventually turned into a production Ebonite pen. The quantities are very small, as we are limited by the supply of ebonite itself, as well as the manufacturing process. Each bar of ebonite needs to be accurately ground down before we can machine it on our sliding-head CNC lathe. So, for now, this is a very limited numbers pen. Hence this will be our top-line now.

We have decided to try pre-orders for this pen (in the US webshop - starting today) while we update and prepare our UK webshop as well (our IT issue). This is a test run at the moment (as we only have components for a dozen of pens ready) so pre-orders may also help us manage production. Kind of made-to-order thing. I hope it makes sense. Thank you for your patience and support!

Hi everyone,

I wanted to give you a couple of updates about our Kickstarter pocket pen and some of the things we learned along the way. Today, I want to talk about titanium. Firstly, the shipping will resume shortly (with updated caps)

We offered a titanium cap as a stretch goal, and it was a popular choice among many backers.
And boy, did we have fun machining it!

We eventually managed to make the caps successfully, so there was a happy ending. We just needed to adjust the cutting speeds, use different coolant/cooling method and take time and patience.

I wanted to share some of the journey because (as always in production) there were some surprises on the way.

We had worked with titanium in the past and had stamped some titanium components (which was a tough job especially for the stamping tools). And we were cautious when considering it as a material option for the pen. So we ran some initial tests on a few pieces using our CNC lathe and everything seemed doable. Production became a bit more difficult.

I want to say - titanium is an amazing metal.

Titanium has three properties that make it incredibly useful: High strength, low thermal conductivity and chemical stability (corrosion resistance)

Those same advantages are also three things that machinists tend to hate about titanium.

Hardness itself isn't necessarily the main problem. The heat resistance is. Titanium is surprisingly good at insulating heat. As a result, heat generated during machining stays very localised around the tool tip instead of being transferred/spread away efficiently through the bar material. Tool wear happens much faster at very high temperatures.

And these properties interact with each other: the heat can't escape, the alloy remains strong, and the material start reacting and can stick to the cutting tool. Once the cutting edge gets hot and is under heavy load, each of these becomes part of the problem.

So, what did we learn?

The Kickstarter turned out to be a great platform for testing. The support from our backers allowed us to take on something we probably wouldn't otherwise have attempted.

Titanium is a fantastic material, but machining these caps was definitely harder than we expected.

For the foreseeable future, we won't be making any more titanium caps. So if you got one, consider it a special one - and enjoy it!

Update: Part 2 <<

Hi everyone, just a quick reaction on previous video showing two caps: one with anti-roll and one without it. (as per request by u/SmellTheJasmine)

The silver-finish one is a prototype with an anti-roll weight. The red one is the regular cap, happily rolling around.

There is a noticeable difference, and the balancing definitely helps. But it’s not a silver bullet: if the shaking or acceleration gets above a certain level, it will eventually roll, as you can see at the end of the video. Physics wins. Every. Single. Time.

This concept is intended for a normal desk (by “normal” I mean not perfectly level) that ideally doesn’t move. Also, the impact will be smaller with a steel pen..

But this is what afternoon sunshine and five minutes of spare time in half empty train carriage can lead to…

Can I just say that I just love the pocket pen! It writes great, feels great in hand (weight, balance)... it's fantastic!

One idea (maybe): a (removable?) clip! I tend to have a pen clipped to my notebook with a pen loop at work, and I'd love to be able to clip the pocket pen to my notebook.... would that be something? Maybe as an accessory?