Review: Pilot, Muji and Uni <0.4mms

I most enjoy writing with pens that produce a fine line. My writing is fairly small and I need a fine line to help make the letters stand out. When I have a choice of fountain pen nibs I always choose fine or extra fine and I generally don’t buy any ballpoint, rollerball, gel pen, hybrid etc with any wider a line than 0.5mm. I find the sweet spot for my handwriting to be around 0.4mm. Equally I have tried 0.2mms and 0.25mm and find that the cons of fine line pens are more noticeable when you go much below 0.4mm, such as ink skipping and resistance or scratchiness on the page. I find fine pens to be such a versatile part of my toolbox. I use them mostly for writing and jotting but I find I often reach for them to sketch and shade, outline and add accents to brush lettering or calligraphy.

So in the spirit of not having done a pen review for a little while I thought I would review three 0.4mms in my arsenal. These are the Pilot G-Tec-C4, Muji Erasable Pen 0.4 and the Uni Jetstream SXN-150-38 (which is actually a 0.38mm). The title of the post says <0.4mms and I have it on good authority that this means less than 0.4mm. My year 3 maths is a little rusty.

What, you ask, makes a successful 0.4mm pen for me?

  1. No skipping. Fountain pens or felt tips may have a fine nib but are able to compensate for this through ink flow. 0.4mms need to produce a consistent line without any wetness of ink flow (which is why many use polymer inks I imagine). I hate it when 0.4mms skip and I need to go back and refill sections of words; it’s really obvious where you’ve retraced letters.
  2. Saturated ink. Again, other pens with a fine nib benefit from interchangeable choices of ink brands, the saturation of which are down to your preference. Often 0.4mms don’t have the flexibility to allow changing ink brands as refills are standardised. So I think it’s really important that whatever colour you’ve chosen produces that colour effectively on the page.
  3. Every touch of the pen on the page has to leave a mark. Dotted i’s and full stops for example need to be made clear on the first touch of the pen. The alternative to this is having to draw a little scribble every time you need to make a dot. NOT acceptable as I’m sure you’ll agree.

I’ve tested all of these pens out in my Field Notes Shenandoah edition. Normally I would use a Rhodia pad or one of my notebooks with better quality paper inside, but Field Notes work great with fine line rollerballs, gel pens and ballpoints and I’d normally reach for a pocket notebook when I’m using one of these pens; they’re being tested in their natural environment.

Pilot G-Tec-C4: Black

This is a readily available rollerball pen with a needlepoint that you can pick up online or in stationery shops including Paperchase for about £2.50. There is a much wider range of colours available than when I first started using these pens and I’ve tried the purple version too. I really like the simplicity and solidness of the pen’s build and design, although I would say that when writing with it for a long time that the inside of my middle finger can get a bit sore because of the grip pattern. There aren’t any obvious design accents on the pen apart from a Pilot stamp on the barrel (I find this can collect dirt around it! Does anyone else find this?). The pen is really lightweight and this makes it very easy to use posted, which I almost always do. I find the length of the pen unposted slightly short.

This pen sticks in my pencil case pretty much all the time and I find it writes well on the variety of paper that I come across. It meets my key criteria of consistency, blackness and laying down ink even with the slightest touch. I find I don’t need to apply much pressure at all to achieve the line I want. If anything lightening the pressure I usually use has achieved the smoothest line.

Muji Erasable Pen 0.4 

I picked this up on a whim while I was waiting to meet some friends near Tottenham Court Road. There’s a Muji shop not too far away and I had a nose around while I had some time to kill. I like using Muji’s hexagonal twin pens at work and needed to replenish so I thought I would give this pen a go at a cost of £2.50.

Sadly I feel it is £2.50 wasted. When you can spend the same amount of money on the Pilot G-Tec-C4, the Uni or even spend a little bit more to get a fineliner drawing pen such as the edding 1800 profipen, there really isn’t any need to have this in your toolbox.

The pros of this pen are that it looks fairly smart, has a needlepoint like the Pilot and has the trademark Muji label which covers most of the barrel. The eraser is well-integrated into the pen lid and the pen posts well. The ink is more of a grey (and not even a very dark one at that) which I find off-putting and I find to achieve a definite line I need to slow down my writing pace and apply more pressure than I usually would when writing. Dotting I’s for example just doesn’t happen with this pen. It won’t produce ink for such a tiny dot. There’s just not a clear smoothness to the ink on the paper. Also compared to the Uni and Pilot it feels broader than a 0.4mm. Perhaps the ink spreads slightly more on the page.

The erasable ink is interesting. I’d never used it before – it’s novel and I admit it can be useful to avoid blemishing pieces of writing. However I’ve realised I don’t really use fine line pens to produce pieces of writing to share or to display in any way, I’ll generally reach for a fountain pen in that situation or make sure I’m using a pencil to draft. I use them for note taking, brainstorming, making lists, drawing map sketches; generally all uses that relate to my work or to everyday usage, and I don’t feel that erasable ink is necessary for these purposes. A little bit of scribbling out all adds to the authenticity of writing things on the go and trying to keep up with your thoughts. I’ve never felt like not being able to erase ink is a shortcoming of any pen I’ve used. If this is important to you though, admittedly it does erase well, although it does leave an imprint on the paper if you use heavy pressure to write. Apparently the ink can be erased because of the heat and friction caused by the built-in eraser, and if you put it in the freezer the ink will reappear! I haven’t tried this but I’d love for you to let me know if you have!

Erased ink up close.

Uni Jetstream SXN-150-38

Unlike the other two pens we’ve discussed this pen is a retractable which is handy for the situations in which I use fineliners. This pen probably feels the least solid, which is often the case with retractable because you’ve got internal parts which are looser than a lidded pen. Also the overall build quality just looks slightly less professional than the Pilot and the Muji (could be partly down to my choice of the baby pink body… although to be fair all the shades in JP Books on the day were pastel shades!).

For those very inconsiderable shortcomings though I think this is my favourite of the lot, but it is a very close one when pipped against the Pilot. It’s smooth, lightweight, compact, simple, the ink is nicely black, dries basically on contact and I don’t think the line has ever skipped when I’m writing with it. I picked this pen up for £2 and I use it all the time. Performance wise it is quite similar to the Pilot, and I think the two key differences between the Pilot and the Uni Jetstream are that the Uni has a slightly wider barrel with its rubber grip which feels more comfortable to write with for a longer amount of time, and the Uni feels more balanced between a ballpoint and a gel pen than the Pilot.


I always have the Pilot G-Tec-C4 and the Uni in my daily toolbox. They’re both high-performing, easy to use, affordable and fulfil my essential criteria of super-blackness and line consistency. Unless you’re really feeling the lack of being able to erase your writing (in which case I would recommend you buy a pencil…) what more could you ask for?

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