My first real encounter with jumbo pens was reported on these chronicles. That was a Platinum-Nakaya –the nib said so— eyedropper whose dimensions were about 35 mm in diameter, and 135 mm in length when capped.
Big enough I thought. Thick to ease the stress on the fingers and not overly big. Its ink deposit could store up to 15 ml—enough to write a very long novel. Let’s not forget that 15 ml of ink add 15 g to the weight of the pen—a significant value indeed.
Two jumbo pens together with a Pilot Super 100. The lengths of these three pens, from top to bottom, are 166 mm, 186 mm, and 132 mm.
The nib of the first of the pens on the previous picture compared to the Pilot music nib of the Super 100. The inscription on the Jumbo nibs reads HIGH CLASS / HARDEST IRIDIUM / USA STAYEL / SPECIAL / PEN. I wonder if "stayel" was a misspelling for steel.
Later, though, I have encountered other jumbo pens that dwarfed that Platinum-Nakaya.
All three of them are eyedroppers with safety valves to seal the gigantic ink deposits. Their dimensions range between 150 mm for the New Clip (vid infra) and the 180 mm for the bigger in the group. The girth is also generous: between 25 and 32 mm.
I did not have the chance to weight them but light they were not. The ink they could store, of course, is an important factor in the weight and in the balance of the pen. The second of the pens could hold up to 35 ml of ink; the New Clip, 20 ml.
The New Clip's nib compared to the Pilot music nib. The engraving on the former says "Special / Iridium /Pen".
New Clip was one of the brands stamped on the clips manufactured by the company Fukunaka Seisakusho in the 1920s and 1930s. This company also produced some maki-e pens in the 1930s. These jumbo pens might date from some time in the 1930s.
With thanks to Mr. Ishikawa.