纹

Left-side silk radical, the side form of 糸. Anchors 纹 in the textile/pattern family - 纹 originally meant the woven pattern in cloth, later generalised to any line, vein, or grain (ripples, fingerprints, wood grain). Same radical drives 线 (thread), 织 (weave), 红 (red).

Right side 文 supplies the sound (wén → wén, identical) and a strong semantic echo: 文 itself originally pictured tattoo lines on a chest and means 'pattern, marking'. So 纹 = silk-radical + pattern-character, doubling down on the 'design woven into a surface' image. Phono-semantic with unusually transparent semantics.