How Shangyou Inspects No.4 and Hairline Stainless Steel Sheet Surfaces

Shaanxi Shangyou Stainless Steel Co., Ltd. supplies No.4 and hairline stainless steel sheets for architectural, elevator, appliance, equipment and decorative fabrication. No.4 generally has a satin directional texture produced by abrasive finishing, while hairline has a longer and finer linear appearance. Names alone do not guarantee that two producers or lots will look identical. Shangyou therefore recommends an approved physical sample, written visual criteria or a documented control image before volume production. The order should define the base grade, sheet size, finish direction and the viewing side or sides.

The surface is viewed under consistent lighting for direction, texture continuity, shade variation, scratches, pits, dents, stains and embedded contamination. Thickness, width, length and flatness are checked separately from appearance. Protective film is reviewed for type, adhesion, bubbles, folds and compatibility with laser cutting when required. A visual inspection is not the same as a measured surface-roughness test; an Ra value is reported only when the contract defines the range and method. Material from different lots can vary, so visible project panels may require lot control and sample matching.

Buyers should provide the grade, thickness, width, length, base finish, No.4 or hairline reference, grain direction, one-side or two-side processing, acceptable shade variation, film type and intended fabrication sequence. For façade, elevator, appliance or interior projects, include the approved control sample and identify panels that will be installed next to each other. Packaging should separate faces, protect corners and keep the finish direction clear on labels. Shangyou can also coordinate cutting or bending allowances while preserving the visible surface for downstream fabrication.