Getting Started:

  • To keep your nib in tip top condition, remove the Zebra G nib and feed when not in use and use non corrosive inks (The best are Iroshizuku, Diamine and Noodler’s standard inks), rinse with water, and air dry.  When the nib does wear out it is easily replaceable here.

  • The design of the Pro-Flex nib is perfect for maximum inky performance but it isnt the best for travel as the feed is very wet. It's worth emptying the pen and then re-inking after travelling.

What is the difference between the two flex nibs?

Great question, and it turns out quite a lot. Here are the main differences so that you can make the best decision for your style of writing.

Pro-Flex - Pros:


  • Juiciness - It's fitted with a professional calligraphy nib (a Chrome Zebra G) giving you the greatest variance between thick and thin strokes, from hairline up to 2mm.

  • You can purchase Titanium Zebra G nibs for your Spark which last around 4 x longer here
  • Softer - it's a doddle to flex, requiring very little pressure.

  • Ink Flow - The Japanese ebonite (a special type of vulcanised rubber) feed delivers just the right amount of ink.


  • Replacing - because a calligraphy nib's raison d'être is to flex, they're made from alloys which are beautifully soft but can corrode and wear. So, just like a calligraphy pen you'll occasionally need to replace your nib when you notice any wear (available here).

  • Heat Setting - One of the tricks to getting the most from any flex nib is good contact between the feed and the nib. One of the clever things about ebonite is that it becomes malleable with heat, meaning you can achieve a super cosy fit for optimum ink flow. This process is called heat setting and I do it to every nib, but it can occasionally need re-doing if the pen is knocked etc. I'll be making a video to demonstrate this but a quick google will also give you a good number of explanations and videos demonstrating the process. If you're not confident about this I would recommend the Semi - Flex nib instead.

  • Snag - The hairline nib when un-flexed creates beautifully fine strokes but if you're new to calligraphy or using a nib like this you will notice that it may snag on paper simply because it is so fine.

  • Travel - you may experience a bit more ink leakage as the nib is particularly juicy! It will be worth traveling without ink in the convertor and re-inking the pen when you reach your destination.

Semi-Flex - Pros:

  • Maintenance Free - If you're not a calligraphy or fountain pen nerd and want a simple maintenance free writing experience, the Semi-Flex is the way to go.
  • Durability - It's essentially a fountain pen nib (gold plated stainless steel) that has been designed to be make it more flexible so it will be more durable than the Pro-Flex.

  • Smoothness - The extra-fine Semi-Flex fountain pen nib is tipped with Iridium (super hard metal) end where it meets the paper, increasing durability of the nib and making it smoother to write with on a variety of paper types.  


  • Flex - Not really a con as it's still more flexible than 95% of the fountain pens out there, but compared to the Pro-Flex it's not as soft and more effort is required to achieve a thicker stroke. 

  • Hairlines - The pen is tipped which, as I mentioned before, increases durability and smoothness but this means it can't achieve such fine hairline strokes as the Pro-Flex.

  • Ink Flow - Flex nibs are inherently thirsty pens and require the feed to keep up and deliver ink to the nib so that it doesn't run out mid-sentence.  The Pro-Flex ebonite feed is the best in the world at delivering ink and is the main reason for the price difference between the two nibs.  The Semi-Flex has a plastic feed which is good but due to lots of incredibly geeky factors can on occasion run out after lots of juicy inky flexing. It's easy to get it flowing again (by pushing more ink in using the included ink convertor) but it's worth considering before purchasing.

Good to know:

  • Every pen is made using precision 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.

  • Every Pen is dip dyed by hand so may have small colour variations; it's part of what makes your pen unique.

  • We offer a complimentary repair service, so should your Spark pen need a little TLC please contact us .