The pen barrel serves as the skeleton, but the refill is the soul. As manufacturers of metal pens, we have disassembled thousands of refills; we know that 90% of a superior writing experience is determined by the refill. Whether the barrel is crafted from brass, stainless steel, or aluminum alloy, it is always the refill—hidden deep within—that truly engages in a dialogue with the paper. By examining four key dimensions—ink type, tip thickness, writing length, and structural composition—we will help you gain a comprehensive understanding of pen refills, enabling the metal pen in your hand to truly unleash its full potential.
1,Ink Type: The #1 Factor That Changes Your Writing Feel
1.1,Oil-based Ink (Ballpoint Pen Refills)
Composition: Dyes + oil-based solvents (e.g., alcohols, esters); characterized by high viscosity.
Features:
- Writing resistance is slightly higher, offering a distinct “dampened” feel; however, ink flow is minimal, making it extremely durable (a single refill can often write for over 2,000 meters).
- Dries extremely quickly and is highly versatile regarding paper types (it can even write on oil-stained paper).
- Waterproof and fade-resistant, making it suitable for long-term preservation.
- May thicken in low temperatures, potentially affecting writing smoothness.
Applicable Scenarios: Carbon paper, shipping labels, factory records, outdoor work, and archives requiring long-term preservation.
Typical Ballpoint Tip Materials: Tungsten carbide or ceramic; typically quite hard.
1.2,Water-based Ink (Rollerball Refills)
Composition: Dyes or pigments + water + wetting agents; viscosity is similar to fountain pen ink.
Features:
- Offers an exceptionally smooth writing experience with generous ink flow and vivid, translucent colors.
- Dries relatively slowly (prone to smudging); may bleed or feather on standard paper.
- Not waterproof (dye-based inks dissolve immediately upon contact with water); pigment-based inks offer some water resistance but come at a higher cost.
- Shorter writing distance (due to the ink’s high fluidity and rapid consumption).
Ideal Applications: Signatures, calligraphy, writing on high-quality paper, and artistic note-taking where vibrant color expression is desired.
Note: When using water-based refills in metal pens, the cap seal must be airtight; otherwise, the pen tip may dry out if left unused for just a few days.
1.3,Gel Ink (Gel Refills)
Composition: Pigment particles suspended in a water-based gel; a hybrid formulation situated between oil-based and water-based inks.
Characteristics:
- Writing smoothness approaches that of water-based inks, while durability approaches that of oil-based inks.
- Drying speed is moderate (typically 3–5 seconds), and water resistance is excellent (for pigment-based varieties).
- Viscosity is adjustable, allowing for the creation of both ultra-fine (0.38mm) and extra-bold (1.0mm) tip sizes.
- Highly adaptable to various paper types; resists feathering and ink pooling.
Applications: Daily writing, exams, office work, and student note-taking—offering the most balanced overall performance.
Industry Status: Currently, gel ink refills hold the largest market share within the global writing instrument industry.
2,Tip Size: From 0.38mm to 1.0mm – A Small Difference That Matters
The tip size corresponds to the diameter of the ball, measured in millimeters (mm). Different sizes produce distinctly different writing effects. Detailed information regarding the various sizes is provided below.
| Size | Line Width | Best for | One-line comment |
| 0.38mm | Very fine (~0.3-0.4mm) | Accountants, students, detail lovers | Fits tiny grid boxes, but picky about paper – too much pressure may scratch. |
| 0.5mm | Most common (~0.4-0.5mm) | Daily office, exams, notes | The gold standard. Works on most paper. Best balance for metal pens. |
| 0.7mm | Medium-bold (~0.6-0.7mm) | Signatures, contracts, bold marks | Noticeably smoother, gives strong lines – may bleed on poor paper. |
| 1.0mm | Bold (~0.8-1.0mm) | Executive signatures, headings, doodling | Maximum presence – heavy ink flow. Cheap refills may blob or skip. |
How do you choose the right tip size for you?
Consider the size of your handwriting: For writing small text in a 5mm grid notebook, we recommend a 0.38mm or 0.5mm tip; for signing documents or writing headings, start with 0.7mm or larger.
Consider the type of paper you use: For standard copy paper or notebook paper, a 0.5mm to 0.7mm tip works well for everything; however, on poor-quality newsprint or rough paper, a 0.38mm tip may snag the fibers, while a 1.0mm tip may bleed through the paper.
Consider the pressure you apply: Metal pens are typically heavier; if you tend to write with heavy pressure, we suggest choosing a tip size of 0.7mm or larger to prevent the tip from puncturing the paper.
3,Writing Length: Just How Many Words Can a Single Refill Write?
Have you ever had this experience: two seemingly identical pen refills—one runs out of ink after just two weeks of use, while the other continues to write for over a month? This discrepancy is precisely where “writing length” comes into play.
Writing length refers to the total distance (measured in meters) that a single pen refill can continuously trace under standard writing conditions. It is not merely an arbitrary figure assigned by the manufacturer, but rather a value derived from standardized testing—typically conducted using a circular-tracing machine or a mechanical writing machine under specific parameters regarding pressure, angle, and paper type.
3.1,Typical Writing Length by Ink Type
| Ink Type | Typical Writing Length (per standard refill) | Reason |
| Oil-based (Ballpoint Refill) | 2000–4000m | Features an extremely low ink output and high ink viscosity, allowing it to write for a longer duration given the same volume. Some high-capacity oil-based refills can even reach lengths exceeding 8000 meters. |
| Gel Pen Refill | 800–1500m | Features moderate ink flow and excellent smoothness, though ink consumption is faster than that of oil-based pens. |
| Rollerball Refill | 400–800m | Delivers a generous ink flow with high fluidity; offers a smooth, satisfying writing experience, but is consumed the fastest. |
| Hybrid Ink Refill | 1500–2500 meters | Striking a balance between oil-based and gel inks, it offers both smoothness and durability. |
Real-life example:
Let’s assume you write 1,000 words per day (roughly equivalent to the daily note-taking volume of an average office worker). If we estimate each character as a 0.5 cm stroke, you would write approximately 5 meters per day.
- An 800-meter gel pen refill ≈ 160 days (over 5 months)
- A 2,000-meter oil-based pen refill ≈ 400 days (over a year)
- Pls note: In actual use, these conversions may vary depending on factors such as writing pressure and paper roughness.
3.2,Four Key Factors Influencing Writing Length
2.1,Ballpoint Tip Size:0.38mm tip yields approximately 20% more writing length than a 0.5mm tip; a 0.5mm tip lasts about 15% longer than a 0.7mm tip; and a 0.7mm tip lasts about 20% longer than a 1.0mm tip. Consequently, finer tips are more ink-efficient.
2.2,Ink Viscosity:Higher viscosity results in a lower ink flow rate, which in turn leads to a longer writing distance (ranking: Oil-based > Hybrid > Gel > Water-based). However, excessively high viscosity may compromise writing smoothness.
2.3,Ink Capacity:The thinner the tube walls and the fuller the ink fill, the greater the total writing length. Direct-liquid ink cartridges can hold two to three times the volume of standard refills, though this often comes at the cost of universal compatibility.
2.4,Writing Habits and Paper Type:Applying heavy pressure or writing on rough paper increases ink flow, leading to faster consumption. Additionally, intermittent writing may slightly reduce the total writing length due to ink evaporation.
3.3,Writing Length and Your Metal Pen: Why Does It Matter?
Users of metal pens have already made a significant investment in their pen bodies; naturally, they expect the refills to offer commensurate value. The greater the writing length of a refill, the less frequently it needs to be replaced—resulting in lower long-term operating costs.
For Example: Writing 5 meters per day amounts to 1,825 meters per year.
- Using an 800-meter gel refill → Replaced 2.3 times per year (approx. 3 refills)
- Using a 2,500-meter hybrid-ink refill → Replaced 0.73 times per year (approx. 1 refill)
When calculated over a three-year period, the difference in refill costs is nearly threefold. Furthermore, frequent refill changes can also increase wear and tear on the pen body’s threads.
Our advice:
- For Maximum Durability → Oil-based G2 Refills (2,000+ meters)
- For a Balanced Approach → Hybrid-ink or Premium Gel Refills (approx. 1,500 meters)
- For the Ultimate Writing Sensation → Water-based Refills (keep a few spares on hand)
Our Promise: All our metal pens are designed to accommodate the G2 standard, meaning they are compatible with nearly every G2-style refill currently available on the market. We also offer our own exclusive, high-capacity refills.
4,Materials and Structure: Reliability Is Determined by What Lies Beneath the Surface
A pen refill is more than just a tube filled with ink. Its physical structure directly determines whether it leaks, whether the ink flow remains consistent, and how easily replacement refills can be purchased.
4.1,Refill Tube Material: Plastic or Metal?
| Material | Advantages | Disadvantages |
| PP/PE | Low cost; transparent, allowing visibility of remaining contents | Prone to cracking (especially at the tail plug); poor weather resistance |
| POM | Impact-resistant, corrosion-resistant, highly transparent | Slightly higher cost |
| Brass / Stainless Steel | Extremely durable; refillable | Heavy, opaque, high cost |
Our Choice: Although the pen barrel itself is already metal, we remain steadfast in our commitment to using a metal refill mechanism as well—a design capable of withstanding the insertion and extraction forces associated with frequent refills. We primarily utilize metal Parker-style refills; this approach makes it significantly more convenient for users to quickly locate compatible replacement refills in their local markets.
4.2,Ink Delivery Mechanisms: Why do some refills write smoothly down to the very last drop, while others stop working when there is still a third left?
- Wick-Type (Inexpensive Ballpoints): Functions like a cotton wick absorbing oil; the final third of the ink often fails to write. Not recommended.
- Direct-Liquid System (Rollerball Pens): Features a large ink capacity and writes smoothly until the very last drop; however, it is susceptible to damage from drops or impacts and cannot be manufactured with ultra-fine tips. Best suited for water-based inks.
- Ink Tube + Follower Plug (Most Common): Features a section of gel-like sealant at the tail end that advances as the ink is consumed, preventing backflow and evaporation. 90% of gel and oil-based refills utilize this structure—offering high reliability and cost-effectiveness.
- Spring/Piston-Type (Premium Refills): Allows for the complete utilization of the ink supply, but involves a complex mechanism and comes at a higher price point.
4.3,Interface Specifications (The Most Crucial Factor!): Can You Find Refills for Your Metal Pen?
This is the question that concerns every metal pen user most: “Pls don’t make me buy a pen with a refill that’s impossible to find!”
Currently, the most universally adopted refill interface standard worldwide is the G2 (the Parker Standard):
- It measures approximately 98mm in length and 6mm in diameter, featuring a metal spring seat at the tip and a flat end.
- Compatible Brands: Schneider, Schmidt, Parker, as well as a vast array of high-quality domestic brands.
- Whether you visit any stationery store or simply search online for “G2 refills,” you will find an abundance of options to choose from.
Other Interfaces:
- D1: Mini Refills (approx. 67mm)—typically used in multi-color pens or ultra-slim pens; offers poor universal compatibility.
- Lamy M16: Exclusive to Lamy’s own pens; not universally compatible.
- Japanese Standards (Pilot, Mitsubishi, etc.): Mutually incompatible; it is very easy to purchase the wrong refill by mistake.
Our Solemn Pledge:
All of our metal pens utilize the internationally universal G2 interface standard. Whether you are using a refill from our brand or a G2-spec refill from any other manufacturer, they will fit and function perfectly as replacements. You will never face the frustrating predicament of having a perfectly good pen, but no refill to keep it writing.
Summary: How to Choose the Right Refill for Your Metal Pen?
Remember these four golden rules:
- Ink Type:Use gel ink for daily writing; medium-viscosity oil-based ink for business settings; water-based ink for signing; and standard oil-based ink for outdoor use.
- Tip Size:Choose 0.38mm for writing small text; 0.5mm for general use; 0.7mm for signing; and 1.0mm for a bold, commanding presence.
- Writing Longevity:For maximum durability, choose oil-based ink (2,000+ meters); for a balance of performance and longevity, choose gel or medium-viscosity oil-based ink (approx. 1,500 meters); and for the smoothest, most effortless writing sensation, choose water-based ink (though be prepared to replace refills more frequently).
- Refill Standard:Stick exclusively to the G2 interface standard; other specifications may not be reliable.
Finally, as manufacturers of metal pens, we would like to offer this thought:
A truly excellent metal pen should serve as a “lifelong companion.” The pen body remains with you for decades, while the refill ensures a smooth, effortless writing experience every single time. While we cannot decide for you which ink type or tip size best suits your personal preference, we can offer this guarantee: for every pen you purchase from us, you will always be able to easily find the perfect matching refill.
