Many pen reviews will focus on details such as the nib, section, barrel, cap, clip, colour/pattern, decoration, trimmings and their relative dimensions. Rarely is much said about the way the cap fits onto the body, unless, for example, the section is small and the fingers have to grasp the thread (on screw-thread pens), which may sometimes be uncomfortable. It is more common for comments to be made about whether the cap ‘posts’ onto the body or not.
There are several methods of securing the cap onto the body.
Screw thread: The cap screws onto the body. This is by far the most common type of fixing. More on this below.
Push-click: The cap pushes onto the body until a definite click secures the cap. The securing ring is usually at the top end of the section or else at the rear of the section, which engages with a sprung cone or lip within the cap .
Push-squeeze: The cap pushes onto the body until the pressure between the two holds the cap in place. (An example is the Parker 51)
Push-squeeze with prongs: One variation of the push-squeeze is found with the Lamy 2000 and Sheaffer Imperial (and no doubt a few more). One of the disadvantages of the plain squeeze method is that the section can get worn or scratched by the action of pushing the cap onto the body. With this variation, the section is fitted with small raised metal prongs which engage with the sprung cap, instead of the surface of the section itself.
Bayonet: The only example I know is the Visconti Homo Sapiens.
Capless: There is no cap, the nib retracts into the body.
On screw-thread pens, there may be a single thread on the body and it may be quite coarse in pitch but the grooves well rounded. Examples in my collection are the Italix Chaplain’s Tankard, Wing Sung 3008, Delike New Moon and the Moonman C1. In the latter case, the choice of single thread is deliberate as it ensures that the flat side of the cap always lines up with the similar flat on the body for anti-roll purposes, there being no clip.
However, multiple threads are far more common. As you turn the cap, there may be two or more ‘starts’ and the threads are interleaved. In principle, this allows the cap to be engaged quicker and require fewer turns to open and close, although this also depends on the length and pitch of the threads, so in practice there is little correlation. Two threads seems to be the most commonly found, especially for Chinese pens. Three threads are found on modern Parker Duofolds, Mont Blancs and Nettuno. Four threads is the distinctive feature of both vintage and modern Conway Stewarts. Because of this, Conway Stewarts only take between 0.6 to 1.2 turns to release the cap. At the other end of the scale, the Delike New Moon takes 3.75 turns to release (One thread) and the Kaigelu 316 takes 3.5 turns (Two threads). Finally, the unique bayonet fixing of the Visconti Homo Sapiens has 5 starts and takes a twist of just 0.2 turns to release.
Another noticeable feature of screw-thread pens is the way the final cap closure occurs. Generally, the design and machining of the threads provides for a hard ‘stop’, while in others, the threads seem gradually to bind and prevent further closure. The latter is much less common and may just reflect poor matching of the cap and body machining due to tolerances in manufacture.