The idea of a retractable fountain pen — one that clicks open and closed like a ballpoint — has long been the holy grail of pen engineering. The challenge is preventing the nib from drying out when retracted. Platinum has solved this problem brilliantly with the Platinum Curidas Knock-Type Fountain Pen, a pen that combines the convenience of a retractable with the writing pleasure of a true fountain pen.
The Engineering Marvel: Slip & Seal Mechanism
The secret behind the Curidas is Platinum's proprietary Slip & Seal mechanism. When the nib is retracted, an inner cap seals around the nib unit, creating an airtight environment that prevents the ink from drying out. Platinum claims the pen can be left uncapped for up to two years without the nib drying — a remarkable achievement that makes the Curidas genuinely practical for everyday use.
The knock mechanism itself is smooth and satisfying. A single click extends the nib; another click retracts it. The action is precise and reliable, with no wobble or play in the extended position. This is engineering of the highest order.
Design & Build Quality
The Platinum Curidas has a sleek, modern design that sets it apart from traditional fountain pens. The barrel is available in several translucent colours, giving it a contemporary aesthetic that appeals to both fountain pen enthusiasts and those new to the hobby. The translucent body allows you to see the ink cartridge or converter inside, adding a subtle demonstrator quality.
The pen is well-proportioned and comfortable to hold, with a grip section that is slightly textured for a secure hold. Build quality is excellent — as you would expect from Platinum, one of Japan's most respected pen manufacturers. The knock mechanism feels solid and durable, with no sign of the flimsiness that can affect lesser retractable pens.
The Nib
The Curidas is fitted with a rhodium-plated steel nib, available in Fine, Medium, and Broad widths. The nib writes smoothly and reliably, with consistent ink flow and a pleasant amount of feedback. It is not a gold nib, but it performs admirably and is well-suited to everyday writing tasks.
The nib unit is housed within the retractable mechanism and is protected by the Slip & Seal inner cap when retracted. Despite the complexity of the mechanism, the nib writes just as smoothly as a conventional capped fountain pen.
Filling System
The Curidas accepts Platinum's standard cartridges or the Platinum converter (available separately). The converter allows you to use any bottled ink, greatly expanding your colour options. The translucent body makes it easy to monitor your ink level at all times.
Writing Experience
Writing with the Curidas is a revelation. The convenience of a retractable mechanism combined with the smooth, expressive writing of a fountain pen is genuinely transformative. You can click the pen open and start writing in an instant — no cap to remove, no risk of losing it. For those who frequently switch between writing and other tasks, this convenience is invaluable.
The pen is well-balanced and comfortable for extended writing sessions. The nib delivers smooth, consistent performance, and the Slip & Seal mechanism means you never have to worry about the nib drying out between uses.
Who Is the Platinum Curidas For?
- Professionals who need a fountain pen they can use quickly and conveniently
- Fountain pen enthusiasts curious about retractable technology
- Those who dislike managing caps but love fountain pen writing
- Students and note-takers who write frequently throughout the day
- Gift buyers looking for a truly innovative writing instrument
Pros and Cons
Pros: Innovative retractable mechanism · Slip & Seal prevents drying · Smooth steel nib · Excellent Platinum build quality · Convenient one-handed operation · Modern design
Cons: Premium price · Steel nib (not gold) · Converter sold separately · Mechanism adds complexity
Final Verdict
The Platinum Curidas Knock-Type Fountain Pen is one of the most innovative fountain pens of the modern era. Its retractable mechanism, combined with Platinum's Slip & Seal technology, solves a problem that has challenged pen engineers for decades. At £105, it is a premium investment — but one that delivers a genuinely unique and practical writing experience. Order yours from TTPEN UK today.
