Pen Review: The TWSBI Mini

Well, at long last we have been graced with the arrival of the newest birth in the TWSBI family, the Mini.  One of the (almost only) two complaints of the larger sibling TWSBI 540 piston filler is that it a) is too big, and b) does not post.  Well, fear no more, for those looking for a smaller piston filling 540 now have an option in the TWSBI Mini.

Like every other single release thus far, I have been wildly excited to see another new pen come from TWSBI.  When we heard the Mini was coming, the biggest choice was which one do I get for myself?  Since I had picked a Sapphire in both the 540 and the Vac 700, it was time for a change.  Lisa had grabbed a Smoke 540, and since I always wanted a clear TWSBI, I was able to narrow my choices down a bit.

Three TWSBI Mini Pens

Three TWSBI Mini Pens

The Mini comes in three different flavors, all clear transparent, all solid black, or a combination of the two with a black cap, section, and piston knob with a clear transparent barrel called the Classic.  The Classic was the model that most called out to me so this was the one I grabbed.  Lisa decided on the solid black model.  As usual, I took the Medium nib, and Lisa the Fine.

Comparison of TWSBI Mini and 540

Comparison of TWSBI Mini and 540

The first thing to note is the consistency across most of the TWSBI product line when it comes to packaging.  With the exception of the Micarta, the 540, the Vac 700 and the Mini all use the same size outer cardboard box and the inner plastic box.  The white insert that holds the pen on its pedestal is of course different, with the two pedestals being a bit closer together, but everything else is the same.

After taking the TWSBI Mini out, I immediately notice its solid construction and feel.  The barrel has the diamond facets and the piston knob and cap are smooth just like on the big brother 540.  The cap band is smooth and the top of the cap sports the same red logo found on the other TWSBI pens.  The section of the pen brings over the metal trim ring as found on the Vac 700 (even on the all transparent clear model).  I’m not always a fan of this, but usually it is because these trim rings at the section are gold plated and the trim often wears and then pits and looks ugly.  That’s not going to be the case here.  I’m not certain if this is for stability or looks, but my guess is the former.

Three TWSBI Minis

Three TWSBI Minis

Another design feature I immediately notice is the back of the section is threaded for the cap.  Yes, folks, the Mini is designed to be posted and will thread on to the end of the barrel.  There are two starting points for the threads, so lining up the clip with the nib may be tricky, but I discovered an easy way on mine to make it work.  I won’t get too hung up on this however, as I’m sure every pen will either line up neatly or will have one position that lines up if you don’t tighten it all the way.  OR, you just don’t care, so it’s win-win for everyone involved.  There is an o-ring on the barrel end which seems to make for a nice secure stop caused by the friction.

The TWSBI Mini

The TWSBI Mini

The nib, along with everything else on this pen, is smaller.  It’s not necessarily any shorter than the 540 nib, but it is more narrow.  For those with vintage pen interests, think along the lines of the difference between the Esterbrook 1xxx series nibs and the 2xxx series nibs.  When I compare my 540 medium nib with the Mini medium nib, they are the same length, just more slender on the Mini.  I guess this officially makes this a number 4 sized nib, but since they aren’t actually marked, am just speculating.


TWSBI Nibs: Mini on top, 540, and 700

The Mini’s piston knob is smaller, but not difficult to grasp, even with my larger hands.  It operates smoothly, like the 540’s, so don’t expect anything different.  So, let’s get to the filling part, shall we?  Well, for those with the TWSBI Diamond 50 Ink Bottle, you will be pleased to know the Mini fits this bottle and can be used with it.  In fact, I tried this first before even dipping the nib in the bottle.  Sure enough, it fits on the bottle just as you would expect and gets a full fill using this method.  Thread the section and nib back on and you’re ready to go.  It should be noted, for the first fill, it is, of course, recommended to fill through the nib and feed so as to saturate them with ink.  The pen holds 1 ml of ink inside its barrel.

And now for the moment we’ve all been waiting for, the road test.  I had plenty of notes to write down regarding changes to the website, so grabbed one of our notepads and started writing.  It writes just as you would expect a TWSBI to write.  It starts up right away and is smooth with no hesitation or skipping.  The flow is good, near perfect I might say.  One of the comments I get most on my 540 is the flow is a bit wet.  The Vac 700’s can sometimes be a bit dry, this one is right in the middle.  I was very pleased with the writing characteristic of this pen.  I wrote with it for about two hours immediately after inking it up, then set it down for the night.  When I got up in the morning, I started in again with no disappointments.  I’m going to like this pen.

As for size, well, we keep calling it the Mini but give no indication of overall size, well, it is about 4-9/16″ capped and 5-1/2″ posted.  Think iPhone size.  It is about an inch shorter than the 540.  This is a pen I have to post.  With my larger hands, not posting is not comfortable, but thankfully posted length works.  This is a pen that is going to fit nicely into tight spaces.  Have a small inner pocket in your jacket?  How about that side pocket in your purse or briefcase?  This will fit.  If you can tuck an iPhone into it, the TWSBI Mini will fit as well.

TWSBI Mini and iPhone

TWSBI Mini and iPhone 5

The question I’ve been asked most is perhaps will the Mini come out in colors as well?  I don’t know, but I do like the fact TWSBI has ventured off and done a solid black model as well as the Classic.  Some people just don’t like transparent pens and I think TWSBI needs to make some more solid colors for those people.  Sometimes it’s not all about seeing the inner workings of the pen, it’s about the pen working.  With TWSBI, and the Mini, this is definitely a pen that works, and works well.  If you can make it to a pen show any time soon, stop by our table and ask to give one a try.  You won’t be disappointed, that is if you can wrestle it out of our hands first.


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  • Johan Witt

    Excellent review. Thank you! I especially appreciate the close-ups of the nibs. Very useful to give a “feel” for the Mini.

  • Don

    I got my TWSBI Min in F and tried 4 different inks, sailor dark green, Montblanc Royal Blue, Pilot Iroshizuku shin ryoku bluish green, then finally Pilot Iroshizuku Asa Gao. I hate to say it but the pen likes the pilot inks the best.. with the Sailor a close second and the montblanc last place Surprise…Surprise. The nib was smooth…I did a few tiny tine adjustments and got it to right ludicrous smooth. This pen is a freak…It’s smoother then some 500 + dollar Montblancs I have used. I don’t know how the hell they have made such a good product at this price point. I want them to make more pens now and can’t wait for the 540 replacement in plastic and the one in metal

    • Brian & Lisa

      I know, the price on these is just crazy. A good reliable piston filler for $50 is amazing!

      Brian & Lisa

  • Breck

    I have gotten some reports of the Mini cracking at the base of the barrel where one posts the cap. I had thought this problem was solved with the addition of the O ring. Have you all gotten any reports on this? Thanks.

    • Brian & Lisa

      I have not seen or had a report of a single mini cracking and we have sold a LOT of them. Your mileage may vary. With all the reports of 540’s cracking, I can count on one hand the number of pens reported to us that did.

  • farmkiti

    I don’t remember where i saw it, but I did read a comment somewhere that the cracking problem has been addressed. I have the TWSBI Clear Mini fountain pen and I can’t think of a single negative thing to say about it. It writes ridiculously smoothly and feels great in my hand. It posts beautifully with the threads on the back end and feels quite secure. I find it extremely comfortable for long periods of writing. It holds a very large amount of ink – period – not to mention it’s in such a tiny pen! I absolutely love mine and would love to see it in translucent colors. Since I like the Clear model so much, I have also ordered the Vac Mini fountain pen and can’t wait to see how that one works. And oh, BTW: how do they do all this, plus feature piston and vacuum filling, in such an inexpensive pen? This is the first TWSBI I have owned, and I’m sold on the brand. Completely.