The Medium is just slightly smaller than a Large Rhodia Webbie and just slightly larger than a Moleskine Large/Piccadilly Medium notebook. I am pretty sure my Rickshaw Bagworks Moleskine Classic Folio will work with it but I have not had a chance to try it yet.
On another note, here is a picture of the backside of that writing test page:
You can see a slight bleed mark in the top right. That is the Rotring Core with a “XS” nib. When I did the little ink blot, I did not like that I missed some spots, so I went over it a second time. That made it bleed. The Levenger Carbon F is the next one that almost bled. It has a medium nib. That is also the pen with the Private Reserve Ebony Blue. It was basically the same situation but this due to the ink. It started hard and I went over the ink blot a second time.
This is not a full review but just some quick photos and an overview of the new TWSBI notebook. I purchased the Medium size with graph paper. Initial impressions? This is good fountain pen friendly paper! There is a little bit of ghosting or echo on the backside of the page but it is very little. It will not make it so you can’t use the backside of the page. No feathering that I could detect. I can make the paper bleed if I try. Under normal writing conditions, it does resist bleeding even with wet ink/broad nibs but artists may want to proceed with caution.
I noted that Private Reserve Ebony Blue sits on the page for a LONG time. It will need to be blotted. It has been sitting over an hour now and it still looks wet. The paper is smooth but does not feel glassy smooth. Just enough tooth to feel nice.
Laying flat is a big plus! I don’t think I have any other notebook in this size/type that lays flat like this notebook. The even bigger plus is that it lays flat without any effort. I just opened it and it stayed that way. Most of the time I have to break in the notebook for it to lay flat.
The leather-like soft and flexible cover is nice. It goes well with the embossed TWSBI logo on the front and back covers. It was tastefully done, not overdone too.
The rear pocket is paper with red cloth expansion “ribs”. I just realized I really do not know the correct term for those. The ribbon bookmark matches the red cloth on the pocket.
The elastic closure seems like a compromise. It is obvious they could not make the elastic tighter or it will curl up the notebook. Make it any more loose and, well, there is really no point to having a closure.
So, in a nutshell, TWSBI listened to the fountain pen community and made a notebook that caters to it.