karhennuksessa

Karhennus is a surface treatment used in metalworking, leathercraft and woodworking to roughen or texture a surface. The aim can be functional, such as improving adhesion of subsequent finishes, coatings, paints, or patinas, or decorative, producing matte, stippled, or patterned textures. The term derives from the Finnish word karhea, meaning rough, with the -nus suffix indicating a process.

Techniques vary by material. In metalworking, karhennus may involve hammering with textured faces, punching, or abrading with abrasive tools to create uniform or random textures. In leatherwork, roughening the surface is done by abrasion with brushes, pads, or controlled stamping to improve dye uptake and adhesion of finishes. In woodworking, light rasping, carving or scraping can create cross-hatched or subtle grain textures for grip or aesthetic effect.

Applications include preparing a surface for painting or plating, creating tactile features on tools or jewelry, or giving a finished look to furniture and decorative objects. The texture depth and pattern are chosen to suit the material and desired outcome, with care to maintain structural integrity.

Safety and quality considerations include using appropriate personal protective equipment, achieving consistent texture, and avoiding over-roughening. It is common to test techniques on scrap material before applying them to a final piece.

See also: surface finishing, texturing, patination, engraving.