Sumi - Flex Fountain Pen

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Regular price £125.00
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 "Game-changing!" Sumi - The Flexible Fountain Pen


Why isn’t there a fountain pen that writes like a calligraphy pen with no need to dip it in ink?  This is the question I asked myself three years ago. It seemed no one had a good answer so I set about answering it myself.  And after a pile of prototypes, failed experiments and a lot of head scratching, I’m very proud to introduce you to Sumi - The Flexible Fountain Pen!

"Tom has done it again! I mean...just look at it! This is his new fountain pen that has a flexible fine nib which means you can have your thick and thin lines without having to dip your pen in ink every so often!"

Hazel's Lettering (professional calligrapher)

The Sumi's secret ingredient is the custom, super-flexible nib which allows you to write as thin as 0.4mm, and up to 2.0mm when fully flexed. It’s also tipped with a German iridium tip for a smooth writing experience (no more scratching or ink splatters) and, unlike standard calligraphy nibs, it will last a lifetime.


It's springy, fun to use and incredibly addictive!

The Sumi pen comes with an ink converter (a fancy re-fillable ink cartridge) which means you can use the pen with 100s of different coloured fountain pen inks. I highly recommend using Diamine Inks which have been specifically tested for use with the Sumi pen. They’re lovely and juicy and even have a metallic colour range which shimmers in the light! We do not recommend using ink cartridges with the Sumi pen as the ink flow will not keep up with your writing and is likely to result in 'rail roading'. 


Just as the function of the pen honours calligraphic heritage, the form is also inspired by a traditional quill and ink set. I’ve paired the design back and have also infused the aesthetics with a minimalist Japanese look (hence the name Sumi which means ‘ink’).  The making of the pen is a different story, and is firmly rooted in the 21st century. By using state of the art CNC watchmaker’s lathes I can create a supremely refined and well balanced pen.

A big question (which, as a designer I often grapple with) is this: ‘We are all individuals so why are the products we use on a daily basis so often utilitarian and say so little about us and our own individuality?” It’s the reason I wanted to create a pen which is as unique as its owner. So I spent a lot of time developing a new dyeing process taken from fine jewellery production techniques.  Every pen is individually dip-dyed by hand using this technique, making each one subtly unique.

Sumi - Flexible Fountain Pen, designed to celebrate creativity, craft and individuality. 

Good to know & FAQs:
  • Full FAQs can be found here.

  • The brass stand has been designed to be equally happy standing on your desk, or in your bag on the go.

  • The Sumi pen works beautifully with all Diamine Inks (including shimmer!) You can find them here).  Be sure not to use calligraphy specific ink as this can clog the pen.

  • Like a good pair of leather shoes the Sumi Pen will soften and become even more flexible with use. It will adapt to your style of writing and become unique to you. As such, it may take a little time for your pen to ‘settle in’. If you have any questions at all about the functionality of your pen, please get in touch as we are always very happy to help.

  • We recommend you flush your Sumi pen thoroughly before use. This will remove any oils from the nib which are present during manufacture, and will impede ink flow. Any of the following are good options: our Nib Cleaning Solution, distilled water or water with a touch of dish soap.
  • If you are having any problems with your nib 'rail-roading', this is usually down to ink flow issues and residual oil on your nib (see above). Make sure you are writing slowly so that the ink has a chance to catch up with your writing. 
  • The Sumi pen is designed to compliment your calligraphy pen and not replace it entirely. If you're looking for the maximum softness and flex please take a look at my Flourish Pens.

  • Measures 165mm with brass stand, 150mm without and weighs 67g with brass stand, 25g without.

  • Each pen is beautifully presented in a gold foiled gift box.

  • Every pen is machined from solid metals on a lathe used for making fine watch and aerospace grade components, so you can be sure your pen will write perfectly for years and years to come.

  • Brass naturally develops a patina over time and with use. You can choose to embrace this unique change or our brass polish to bring it back to it's gleaming best.

  • Every Pen is dip dyed by hand so may have small speckles or colour variations; it's part of what makes your pen unique and is not considered a fault.

  • We offer a complimentary repair service, so should your Sumi pen need a little TLC please contact us .
  • We Ship Internationally.
  • We take care of VAT and customs duty for European customers.
  • Your order will be shipped within 48 hours when in stock, please refer to lead times of the product you are buying, as some handmade / hand dipped products may take longer until we send them. Delivery is calculated from dispatch.
  • All UK orders are shipped using Royal Mail Tracked 48 and are free over £60. If you need your order by a specific date there is a next-day Special Delivery option.


  • If your order contains a pre-order item, your whole order will be shipped together in order to minimise our carbon footprint. So please refer to pre-order delivery times in this instance. Alternatively, you can ask us to split the order. In this case additional delivery costs will apply. Please contact for further information.
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tomsstudio Sumi - Flex Fountain Pen Reviewtomsstudio Sumi - Flex Fountain Pen Review

Sumi flex pen

This is the most luxurious pen I have ever had . I am a fountains pen lover and a stationary addict . I am a proud owner of nearly 30 fountain pens. This is the best .

Lavanya S.
United Kingdom United Kingdom
tomsstudio Sumi - Flex Fountain Pen Review

A fantastic pen combining arts and practicality

This handmade pen looks fantastic, with lovely sunrise colour. You can bring along the pen during your staycation, so convenient!

Suet S.
Hong Kong Hong Kong

Beautiful pen

This pen is beautiful - it feels lovely in the hand and it looks good on my desk. The nib is wearing in nicely and I reach for this pen more and more. Am very, very pleased with it.

Sarah H.
United Kingdom United Kingdom

Beautifully made and presented pen

I have loved this pen as I started writing with it. Lovely flex, lovely feel in the hand, lovely and smooth over paper. It’s my first real fountain pen and I couldn’t be happier. I really love everything about this. Thanks Tom!

Melinda C.
Australia Australia

Beautiful Pen!

Had a little trouble getting the ink to flow, but Tom was super helpful and responsive when I asked him for more tips on Instagram! I love using this pen, it looks beautiful on my desk and makes me want to write letters to everyone I know. Looking forward to seeing the nib adapt more to my style the more I use it :)

Kym L.
United States United States

Why Tom's Studio

Values & Craftsmanship

Tom still uses the same design principles as the very first pen he made for his wife. It's important to him to create products that his customers will cherish for the rest of their lives. It's why each every one of my products has a lifetime guarantee.

 "Have nothing in your house that you do not know to be useful, or believe to be beautiful." William Morris

Creativity Tools

Tools of the past were made by master craftspeople that cared passionately about their craft and the experience of the people using their products. We seem to have lost the 'soul' of these tools in the age of mass production. It's my mission to bring the creative soul back to the tools we use every day.

"Creativity is contagious, pass it on" Albert Einstein

Tried and Tested

Seeing his calligrapher wife, Gemma Milly, using a mass-produced calligraphy pen inspired Tom to craft a collection of pens that matched the high quality of her work. Using a 60-year-old engineering lathe, he now makes pens for some of the world’s most celebrated calligraphers and stationery brands.

"Beauty Is The Harmony Of Purpose And Form." Alvar Aalto

A Labour Of Love

From the first pen I made for my wife to the pens I now make for my customers around the world.  I put the same care and attention into each and every pen.  I love what I do and hope that it shows in the finished product.

old fashioned lathe