I’ve had the TWSBI Mini ($50-$55) since Christmas but I haven’t reviewed it because I’ve been waiting for a new EF nib unit. Initially, I got it with the F nib thinking I’d like to be able to compare the F nib with the EF nib I have on my TWSBI Diamond 540*. What I discovered is the F nib is quite broad and made me quite sad — I tend to prefer either razor fine or italic/stub nibs, no in-between. So, in order to give a fair and balanced review of the new Mini, I decided to wait until I could swap out the nib unit with the EF and compare apples to apples.
I liked the overall looks of the clear demonstrator model of the TWSBI 540 so I purchased the clear demonstrator Mini as well. The clip shape is ever so slightly different (I think the new 580 uses the same clip design) and TWSBI added threads to the end of the pen so that the cap will post snugly. The silver band at the base of the cap is narrower as well. Otherwise, the size is the only visible difference between the 540 and the Mini.
The 540 is about an inch longer than the Mini which measures about 4.5″ capped which is about half an inch longer than a Kaweco Sport. The barrels on the 540 and the Mini are the same diameter. Uncapped, the Mini is about 4.25″ long and with the cap posted its 5.5″ long which is comparable to most full-sized pens. The Mini weighs 20gms (full of ink and capped) which is 7gms heavier than a Kaweco sport but 8gms lighter than the full-sized 540. In my current pen collection, the TWSBI 540 is as weighty as my Lamy Studio which has an all-metal body.
The nib of the Mini is more slender than the 540 nib but the same length with the sample decorative filigree and logo.
As expected, in writing tests, the Mini performed exactly the same as the full-sized 540 but was more comfortable in my hands for long writing sessions. The nib is smooth on the paper and writes continuously without any need to prime it. (If pausing while writing, some other fountain pens will dry out requiring that I scratch on a scrap of paper to get it going again which is often referred to as “priming.”)
The ink capacity is not as large as the 540 but both use the same built-in piston filler which is easy to use. The Mini has held enough ink to keep me writing for about a week without needing to refill so it definitely hold more ink than the standard European cartridge.
If you are looking for an upgrade to the Kaweco-sized pens or want to use a lot of bottled inks, I recommend the Mini.
*The TWSBI 540 has been discontinued and replaced by the upgraded Diamond 580.
(This pen was tested on the Miquelrius medium flexible 300 grid paper book purchased from B+N.)