bluesteel

Bluesteel is a descriptive term for steel finished with a blue-black oxide layer produced by various bluing processes. It is not a distinct alloy but a surface treatment applied to many carbon steels and tool steels. The oxide film gives a characteristic blue sheen, modest corrosion resistance, and reduced glare, while preserving the underlying mechanical properties of the steel.

Bluing methods include hot bluing, rust bluing, and cold bluing. Hot bluing involves heating the steel in a controlled bath (often oil) to form a magnetite layer. Rust bluing (also called bloom bluing) uses a controlled rusting process that is then oiled to stabilize the finish. Cold bluing uses chemical solutions to produce a blue-black oxide at room temperature. The choice of method affects color depth, durability, and the level of rust protection.

The protective oxide layer in bluesteel is relatively thin and can wear away with abrasion or heavy use. Bluing does not render steel rust-proof; routine maintenance with oil or protective coatings is necessary to slow oxidation. Re-bluing or touch-up is common as wear develops.

Applications of bluesteel are primarily in firearms components such as barrels, frames, and slides, as well as knives, swords, and decorative hardware. Historically, bluesteel finishes were favored for their appearance and traditional look. In modern production, other finishes like parkerizing or modern chemical films are often used, but bluing remains valued for authenticity and aesthetics in collectibles and historical reproductions.