My first TWSBI was the Diamond 530 piston filler. I loved this pen, its steel nib was nice and smooth for a fine and the faceted barrel captured the light beautifully. I used the pen frequently for a year (my collection was smaller then) getting through many refills of ink until one day it developed a couple of cracks. One was near the barrel/grip screw threads and another on the filler cap, the first one causing a few ink leaks. TWSBI after sales support is often reported to be excellent, so I should have sent it for repair but I never got round to it. Instead it languished in my drawer for a long time until I finally chucked it away. I kept looking at the 540 and then 580 but in the back of my mind the longevity of use meant it never seemed like a good value proposition.


After listening to a few Pen Addict podcasts where they waxed lyrical about the TWSBI Eco mentioning the much improved build quality and great value I took the plunge back into the TWSBI world to see what the fuss was about. A demonstrator pen is always good for showing off inks so whilst I wasn't intending to use this as a daily writer the clear barrel and 1.1mm stub nib would work excellently for testing.

The packaging that the pen came in was a rather nice frosted plastic box, simple and functional with a wrench and silicon grease for disassembly and reassembly of the pen. I normally don't keep packaging but the plastic box is very useful for storing my eye dropper and cartridge refilling tools so it remains.

Cap and Filler

I would definitely characterise the pen as having a functional appearance rather than being attractive in any way, unlike the Diamond series of pens. Uncapped and from the barrel down to the nib it looks relatively elegant and with a good ink sloshing around the barrel it comes into its won. The filler cap and pen cap however are just too bulky, too blocky and generally unattractive. It reminds me of the arts tower in Sheffield, brutalist architecture applied to a pen and this isn't a good thing.

The black cap is big, chunky and sticks out a mile from the barrel when the pen is capped. Whilst visually unappealing I can see how this design would really help the product robustness. The metal ring on the cap is chrome finished with 'TWSBI' engraved on it. The clip is functional and appearance wise in keeping with the 'brutalist' theme of the rest of the pen.


The piston filling mechanism works well and you can easily get a complete fill, though you may have to force the air out and do a second fill pass to maximise the volume of ink. The capacity seems quite large, I typically don't fill it completely however as I like to see the ink sloshing around and change up more frequently.

The stub nib is pretty good in use, it feels a lot more like a cursive italic than what I would expect from a stub with more feedback on the page and more line variation. It doesn't seem to have any extra tipping material at all. It is made of a rather stiff steel, the tines nicely aligned and the flow consistent with no skipping or hard starts. It feels like a Jowo nib and after a bit of research it looks like this may be the case on this generation of product. If you leave this pen uncapped for a while it doesn't seem to dry out, which would make it good for a meeting pen.


The pen is relatively long and broad, but the grip section is still a sensible diameter. It has a slight lip just before the nib which helps with handling and the pen balances nicely. It doesn't need to be posted to be a usable length which is lucky as it becomes back heavy when you do so. It is however well designed so that when posted twisting the cap doesn't accidentally trigger the piston mechanism and it grips into position very firmly.


The pen cleans easily, I found filling it half with water and giving it a good shake tends to be the quickest way to clean it out and complete the task. As with most demonstrators and piston fillers there was some slight residue left even after a thorough cleaning, but when the next ink was filled it went away. If this residue does annoy you then the joy of this pen is that it can be completely disassembled using the supplied tools, but I wouldn't recommend doing this every time you empty the pen.


At £28 (as of publish date) this pen is at a similar price point to other great writers like the Lamy Logo or Faber-Castell Loom, so to get a piston filler shows what great value the pen is. It writes well and is nice in hand but really looses out in the looks department. This is a great way to try bottled ink and if this is your price range then you should consider this pen as it is very well built, but the Diamond 580 is a much prettier pen for around £42 (assuming the QC issues are a thing of the past) if your budget stretches this far and you want a piston filled demonstrator. For my money however I would get the Loom or Logo as they just look much better.

Where to Buy:

See here for my recommendations for buying stationery on-line. This pen was bought for this review and to add to my collection from Cult Pens who support this blog with a kind discount on items in exchange for an honest review. I recommend going and checking out their offers section if nothing else, there are some superb bargains.