Fountain pen ink on Day Timer paper in my Filofax

This is a quick post for Joshua, who commented on Twitter about how poorly Day Timer pages take fountain pen ink with his medium-nibbed Lamy. Rori suggested that he try a finer nib, and I have medium, fine and extra fine nibs on my Lamys, and Day Timer pages, so I thought I would conduct an experiment!

When I tried to write with my beloved fountain pens in my new Day Timer diary at the start of this year, I also noticed the terrible bleed-through on the pages. This surprised me because in other ways the Day Timer paper seems generally better than other paper I have used in my Filofax. Even my Registrars' ink, which doesn't even bleed through on thin paper, bleeds through Day Timer!
So here's the test I did with my different nibs and different inks.

It doesn't look too bad on this side, and you can only see the minor feathering if you look closely. But on the other side of the page...

Really bad bleed through, which makes the other side of the page practically unusable!!

That's why I use biros in my agenda... I would love to use my fountain pens, but the paper just can't handle it! Filofax paper repels the ink, and Day Timer paper just sucks it in too much! I haven't tried other wet inks such as my V5s, but I might soon, although I'm quite happy with my 4-colour pens at the moment!