To provide a surface treatment method for an aluminum material by which rolling impression, extrusion impressions, or the like, on formation of a stock are eliminated, further, uniformity and reproducibility are made enough in a surface gloss and color tones, and extremely low surface glossiness can be imparted over a wide range.
The low gloss surface treatment method includes: a first stage where the surface of an aluminum material composed of aluminum or an aluminum alloy is degreased; a second stage where oxidation treatment for forming an oxide film is performed; a third stage where acid etching treatment is performed in an acid aqueous solution; and a fourth stage where it is dipped into an alkaline aqueous solution, and is subjected to alkali etching treatment, and the first stage is a non-erosion degreasing stage. The variation ΔRa in the surface roughness of the aluminum material before and after the non-erosion degreasing stage is preferably controlled to ≤0.05 μm.
TAKIGAWA HISASHI
Tomohiro Nakamura
Mitsunaga Igarashi