The Relationship Between Mirror Polish and Rust Resistance — Not Just for Looks

  • May 25, 2025

  • In the world of knives, a mirror polish is more than just an aesthetic choice. Finishing the surface of the blade to a mirror-like smoothness has a practical benefit as well: it can help reduce rust formation.

  • A Smoother Surface Means Less Moisture Retention

    Rust occurs when water or acids linger on the blade’s surface and cause oxidation. A mirror finish significantly reduces microscopic grooves and grind marks, creating a surface that is exceptionally smooth. This allows water droplets and residue to slide off more easily, preventing them from sticking and triggering corrosion.

  • Not All Steels Benefit Equally from a Mirror Finish

    The effectiveness of mirror polishing in rust prevention varies depending on the steel type. Let’s take a closer look:

  • Carbon Steels: White #1, White #2, Blue #1, Blue #2

    These high-carbon steels, often called "hagane," are extremely prone to rust. They contain little to no chromium or rust-resistant elements. While a mirror finish can make the surface smoother and slightly slow down rust formation, it cannot prevent rust entirely.

    These knives require vigilant maintenance—thoroughly drying them after use and applying a light coat of oil is essential.

    White steels are known for their ease of sharpening and clean cutting edge, while blue steels, with added elements like chromium and tungsten, retain sharpness a bit longer. However, both remain highly susceptible to rust, regardless of surface finish.

  • Stainless Steels: Ginsanko, VG10, Powdered Steels, etc.

    Stainless steels contain a high amount of chromium, which makes them naturally resistant to rust. When combined with a mirror finish, their rust resistance improves even further, allowing them to handle small amounts of moisture without immediate damage.

    This makes them much easier to care for on a daily basis. However, keep in mind that no steel is truly rust-proof—neglect can still lead to corrosion over time.

  • Mirror Polish: Its Benefits and Limitations

    Mirror polishing is not just for visual appeal—it’s a functional technique that can help reduce rust. But it's important to understand that it does not eliminate rust risk, especially with high-carbon steels.

    Even the most beautiful mirror finish won’t stop corrosion if the blade is neglected. In other words, a mirror finish is a supportive measure, but daily maintenance is still crucial.

  • Should You Choose Mirror Finish?

    Whether or not to opt for a mirror-polished blade depends on your usage environment, the type of steel, and your willingness to maintain the knife.

    • If you’re committed to careful upkeep, carbon steel + mirror polish will reward you with top-tier performance and aesthetics.
    • If you value ease of maintenance, stainless steel + mirror polish offers the best balance of practicality and beauty.

    In the end, mirror finishing combines beauty and functionality. When you understand both its benefits and limitations, you'll be in a better position to choose the knife that truly suits your needs.

Explore Sakai Craftsmen's Art of Mirror Polished Japanese Knives |

These knives, meticulously finished by highly skilled craftsmen, boast a beautiful mirror polish. Reflecting years of tradition and expertise, these mirror-finished Japanese knives epitomize the craftsmanship of Sakai artisans. We respect this tradition and craftsmanship and strive to offer our customers the opportunity to experience their excellence firsthand.

Mirror Polished

The Origin of Craftsmanship

  • "Honyaki" — A Blade Forged in Determination

    There are many paths in the craft of knife making, but honyaki is like a steep mountain trail—beautiful, unforgiving, and not for the faint of heart. On the other side lies a breathtaking view, but not everyone gets to see it.

  • A honyaki knife is made entirely from high-carbon steel. Most Japanese knives are constructed by laminating hard steel with soft iron to balance sharpness with durability. But honyaki? It’s steel alone—no safety net. That makes it uncompromisingly difficult. A slight misstep in the heat treatment, just a few degrees off, and the blade can warp or crack. Sometimes you forge ten and not a single one comes out right. That’s honyaki.

  • And that’s why I say honyaki is the shape of a craftsman’s resolve. There’s no room for shortcuts. Every time I stand before the forge, I have to still my mind and say, “Please, let this one come out right.” It’s less like work, and more like a quiet kind of devotion.

  • But here's the thing—when a honyaki knife does turn out well, it’s something else entirely. The tip glides effortlessly, the blade moves through ingredients like it’s reading the cook’s intentions. It’s hard to describe in words, but there are moments when it feels like the spirit of the tool is alive. That’s the magic of honyaki.

  • I hope chefs around the world will get a chance to hold one. But remember—honyaki is not a strong knife, it’s a delicate one. It will chip if mistreated, it will rust if neglected. But if you treat it with respect, it can become a lifelong companion in your culinary journey.

  • This idea of "putting your heart into a tool" might sound uniquely Japanese. But the moment you hold a honyaki, you might begin to understand exactly what that means.

KIREAJI's Three Promises to You

  • japanese_knife_made_in_Sakai

    1. Exceptional Japanese Knives

    Our knives, crafted by Sakai City's master artisans, combine traditional techniques with carefully selected materials, delivering unrivaled sharpness and durability.

  • 2. For a Lifetime of Use

    At KIREAJI, we see knives as lifelong companions. Each knife comes with a free saya, and we offer Honbazuke hand-sharpening by Shiroyama Knife Workshop in Sakai City.

  • 3. Supporting the Joy of Continued Use

    KIREAJI knives are made to grow with you. That’s why we provide trusted after-sales care (fee-based) .