Stainless steel, as its name suggests, is well known as steel that resists staining. By adding at least 12% chromium to iron, a natural oxide film forms on the surface, protecting it from rust.

Its history is relatively recent, beginning in the 18th century with the discovery of chromium in ore. Research on alloys progressed in Europe, leading to chromium-iron alloys in the 19th century, and by the 20th century, “rust-resistant iron” was developed by mixing chromium and nickel into iron.

In Japan, stainless steel became widely recognized during the rapid economic growth of the 1950s and 60s, when it was used in kitchen sinks for new suburban housing developments. Since then, it has found its way into bathtubs, architectural materials, and various everyday applications.

Stainless steel is characterized by its distinctive silver color. While coloring methods like painting and plating have been tried, these often suffered from peeling and fading, limiting durability.
At Abel, we focused on the oxide film naturally forming on stainless steel surfaces. By electrically and chemically growing this film’s thickness and using light interference, we achieve a rich black finish that is both durable and integral to the metal itself.

References:
“SUS ga Kuroobi Kinzoku Urushi — Eigiki to Nazukerareta Otoko: Sono Myōmyōtaru Ikizama” by Hideki Iai
“The History of Stainless Steel Invention” by Takashi Suzuki (Agne Technical Center)

Magnetism: Some stainless steels are magnetic, while others are not.

Type 18-8 (SUS304) is non-magnetic, whereas 18Cr (SUS430) is magnetic. However, SUS304 can become magnetic after processing. This difference stems from their crystal structures. Austenitic stainless steels are non-magnetic, while ferritic and martensitic types are magnetic. When SUS304 is processed, part of its austenitic structure transforms into martensite, causing it to attract magnets.