aufrauen

Aufrauen is a German verb meaning to roughen or abrade a surface to create texture or improve adhesion. The action is typically mechanical and can involve scratching, scoring, or other abrasion methods. Commonly, aufrauen is used in contexts such as painting, coating, gluing, and finishing, where a roughened surface promotes better bonding of primers, adhesives, or sealants. It is also used in road and civil engineering to describe preparing a surface for resurfacing by restoring texture.

In practice, the term appears in instructions and technical specifications across industries such as metalworking, woodworking, automotive refinishing, and construction. For example, before applying a primer or adhesive, workers may first aufrau(en) the substrate to ensure proper adhesion. The process helps to remove glaze, oxidation, or contaminants and to create micro-roughness that enhances bonding strength. The related concepts include other surface-preparation steps like cleaning, degreasing, and sanding, as well as the contrasting action of glätten (to smooth).

Grammatical notes: aufrauen is a separable verb, so in finite clauses the prefix is detached (for example, Ich raufe die Oberfläche auf). The past participle is aufgeraut, and it is used with auxiliary haben (Ich habe die Oberfläche aufgeraut). The term is primarily used in technical language and is understood as a prep step to improve adhesion or friction.

See also: Schleifen, Schleifen und Glätten, Oberflächenbehandlung. In English, the equivalent terms are to roughen, abrade, or rough up a surface.