SELENOUS ACID

$89.99 – $699.99

Selenous (Selenious) Acid, Dry Granular, Lab Grade, Argon Packed.

Hygroscopic, Potentially Deliquescent. Keep Tightly Capped When Storing.

The major uses are in protecting and changing the color of carbon steel, especially steel parts on firearms. The cold-bluing process uses selenous acid, copper(II) nitrate, and nitric acid to change the color of the steel from silver-grey to blue-grey, blue-indigo or (nearly) black. 100% miscible in water.

ODORLESS but POISONOUS and TOXIC! Professional Use Only with Approved, Appropriate Personal Protection Equipment (PPE).

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SKU: N/A Category: CHEMICALS Tags: argon packed, cold blue, cold-bluing, dry selenous acid, LAB CHEMICALS, SELENIOUS ACID, SELENOUS ACID

Selenous Acid, (a.k.a. Selenious Acid), in dry granular form, is lab-grade and argon-packed. It is hygroscopic and may deliquesce, so it should be kept tightly capped to prevent the incursion of atmospheric oxygen and moisture. If possible, store it in a dehumidified area. The addition of an O2 absorber is recommended.

Its primary applications include protecting and altering the color of carbon steel, particularly in firearm components. The cold-bluing process employs selenous acid, copper(II) nitrate, and nitric acid to transition the steel’s color from silver-grey to blue-grey or black. An alternative method uses copper sulfate and phosphoric acid. This process creates a copper selenide coating, which is distinct from other bluing methods that produce black iron oxide. Historically, some razor blades were also manufactured using blued steel.

Selenous acid is also utilized for the chemical darkening and patination of copper, brass, and bronze, yielding a deep dark brown hue that can be enhanced by mechanical abrasion, such as buffing and burnishing.