InktendInktend / Pen library / Aero
Aero
A cigar-shaped, torpedo-profile demonstrator with a smooth steel nib and a distinctive silhouette on a desk.
A solid mid-range option once someone has decided fountain pens are a habit worth investing a bit more into.
Specs
About Diplomat
Founded in Nuremberg in 1922, Diplomat produces a range of German-made pens spanning entry-level cartridge pens to premium limited editions. This model, Aero, dates to 2016.
How to fill the Diplomat Aero
Fill it two ways: snap in a pre-filled international cartridge for convenience, or use a converter (a small plunger or twist mechanism that installs the same way a cartridge does) to draw ink from any bottle. The converter route opens up the entire world of bottled ink, which is where most of the hobby's color variety lives.
Choosing a nib size
Nib size determines line width, not writing pressure: fountain pens are meant to glide, never press. Extra-fine (EF) suits small, dense handwriting and thin paper; fine (F) is the most broadly recommended default; medium (M) shows more ink character and shading; broad (B) and stub grinds favor bold, expressive strokes and calligraphy-adjacent writing.
Keeping it clean
A quick flush with cool water every time you switch ink colors, plus a full clean every 4 to 6 weeks of regular use, is enough to keep the nib and feed performing well. Inktend's cleaning reminder is tuned to a 21-day baseline and adjusts naturally to how often you actually refill.
Pairing inks with the Aero
Because refills are quick with a cartridge or converter, this is a good pen for rotating through several colors rather than committing to one; sample vials work especially well here.
Frequently asked questions
More from Diplomat
Specs on this page have been individually verified against manufacturer and retailer listings.