brown decay metal rust Rusty Rusted steel Steel plate texture background coarse diamond plate diamondplate grunge industrial iron non skid plate rough San Francisco sidewalk surface urban asphalt diamond-plate non-skid Portland city rivet rivets worn air design grungy MIG old oxide plane airplane plate metal plate plates scratch sheet speckled textural textured textures weathered construction diamond metallic oxidation pattern rusting rusty floor flooring garage grip panel ridged security box square strong tile tough