Grass Padrique | The Fabulous Scientist
The Uni-ball One is a gel pen designed around one particularly distinctive feature: its ink. Uni developed a pigment-based formulation with relatively large pigment particles that tend to remain closer to the surface of the paper rather than being absorbed deeply into the fibers. The result is unusually dark, crisp black ink and particularly vivid colors. The ink is also designed to dry quickly and resist bleeding and smudging.
The Uni-ball One F is essentially the more refined version of the One. Its barrel is slightly wider, and its construction incorporates additional metal components around the tip to give it a lower center of gravity and greater writing stability. Uni describes this as a stabilizing mechanism intended to let the pen write comfortably with relatively light pressure. The F also has a metal tip section and comes in more subdued, sophisticated body colors.
My Personal Review
I have a confession: I may have a weakness for pens that make writing feel ridiculously satisfying.
Enter the Uni-ball One F.
At first glance, it doesn’t scream for attention. In fact, mine is in sage green, a muted, understated color that feels right at home in my stationery collection. Mine has the 0.5 mm tip, which I find to be a sweet spot for everyday writing—fine enough for notes, but still substantial enough to show off that gorgeous ink.
And oh, that ink.
It is black. Really, really black. Even blacker than the ink I recently reviewed which is the Platinum Carbon Black.
The Uni-ball One’s specialty is its pigment-based ink, which is formulated to stay closer to the surface of the paper rather than disappearing into the fibers. The result is a remarkably dark and vivid line.
But specifications aside, here’s how I would describe it:
The nib glides like butter on a heated pan.
Yes, I know. That’s an unnecessarily dramatic description for a gel pen. But honestly, it’s accurate.
The tip glides effortlessly across the page, and I’ve tried it on several kinds of paper. It performs beautifully on all of them, but I particularly enjoy it on my fountain-pen-friendly papers. There’s something wonderfully satisfying about putting down an incredibly smooth, intensely black line on a good sheet of paper.
The ink also dries quickly, which I appreciate because on some days particularly when I need to write notes while on an important meeting I would need to write fast and ink also has to dry fast. It’s also moisture-resistant, making it a practical choice for notes that might encounter the occasional splash, spill, or sweaty field notebook.
And that brings me to the real reason I bought the One F.
Convenience.
As much as I love my fountain pens, there are times when carrying one around isn’t particularly practical—especially during fieldwork. When I need to quickly jot down an observation, a measurement, a brilliant idea, or possibly something that I will completely forget five minutes later, I want a pen that I can simply click and write with.
The Uni-ball One F fits that role perfectly.
It’s retractable, so there is no cap to lose and no nib to worry about. Just click, write, and move on.
The construction also feels reassuringly sturdy. I like the strong clip, which feels like it can survive being attached to a notebook and pulled out repeatedly. The body appears to be made of tough plastic, yet the pen doesn’t feel flimsy. The One F also incorporates a stabilizing mechanism around the tip that gives it a lower center of gravity and a more stable writing feel.
For me, this makes it a very practical grab-and-go pen.
And because I’m me, practicality eventually turns into another project.
I’m seriously considering using this pen for sketching.
That incredibly dark black line is just begging to be used for quick sketches, especially when paired with watercolor. The fast-drying, water-resistant qualities of the ink make the idea even more tempting. And I just might start doing line and wash sketches with this one, hopefully, soon.
I’ve also paired my sage-green Uni-ball One F with my A6 leather notebook of ideas, which happens to be in a beautiful muted taupe. The combination is almost embarrassingly pleasing: sage green and taupe, dark black ink, leather, and paper. (Note: My phone’s camera has somehow made the color of my pen adjusted to baby blue, but I assure you, it’s much closer to sage green.)
The Verdict
The Uni-ball One F may not have the romance of a fountain pen, but it offers something different: immediate, dependable, ridiculously smooth writing.
It’s the pen I reach for when I want the convenience of a retractable gel pen without sacrificing writing pleasure. The ink is exceptionally dark, the tip is wonderfully smooth, the body feels sturdy, and the clip is practical enough for everyday carry.
Most importantly, it fits the way I actually live.
For leisurely writing at my desk, I’ll probably still reach for a fountain pen.
But for fieldwork, quick notes, spontaneous ideas, and possibly sketching?
Click. Write. Done.
And sometimes, that’s exactly what a pen needs to be.
Do you have one as well? Share your experience with it in the comments section below. 🙂 Happy writing!
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