Uni-Ball Gel Pen One yellow

The uni-ball Gelroller One in Yellow is a Japanese gel pen featuring water-resistant pigment ink, specially formulated to stay on the paper's fibres rather than sinking in. The result: a vibrant, saturated yellow that remains visible and prominent on the page. With a 0.5 mm line width, it writes finely and evenly – the slim white plastic barrel with metal clip sits comfortably in your hand.

Features

• Pigment ink, water-resistant: The ink doesn't penetrate deeply into the paper but deposits on the surface – the yellow stays vibrant and colour-rich, even on smooth, calendered paper. Not archival.
• 0.5 mm line width: Fine, clean line work without fading or feathering – ideal for handwritten notes, labelling and colour-coding in planners or notebooks.
• Ink stays on the fibres: The specially formulated gel ink penetrates less deeply into paper than classic rollerball inks. This reduces bleeding and ghosting on the reverse side – relevant when using thinner papers.
• Colour indicator at pen end: The coloured clip area and cap above show the ink colour – handy when keeping pens in a case or grabbing quickly from a pen collection.
• Metal clip, slim white barrel: The clip opens wide enough to secure the pen safely to notebooks or notepads; the white plastic barrel is lightweight and comfortable in hand despite its slim design.

Use & Tips

• Bullet journals and planners: Yellow is particularly suited to colour-coding systems where a bright, warm colour is assigned to a category or day of the week. On white or cream paper, the yellow appears warm and clear.
• Highlighting and accents: On smooth, ink-resistant paper, the 0.5 mm pen writes precisely enough to underline individual words or add colour-coded margin notes without compromising the legibility of surrounding text.
• Colour labelling: For labels, dividers and index tabs where yellow is used as a signal or category colour.
• Combining with other One colours: The entire uni-ball One range uses the same ink formula – colours can be combined directly without variation in line width or flow characteristics.
• Paper tip: On smooth, calendered paper, the ink flows most evenly. On highly absorbent paper, colour intensity may diminish slightly.

Technical Specifications