Traits Atlas

Codebook, Minimums, Exceptions

Red Patina

Summary: A red to reddish-brown surface film resulting from oxidative conversion of copper. Known for its warm chromatic resonance and painterly variation, it evokes the visual temperature of slow oxidation under heat or arid exposure.

Color: Scarlet to russet tones; sometimes veering into brick, sienna, or dull crimson. Highlights often remain copper-bright, while recessed zones deepen to earthy reds or maroons.

Chemistry: Primarily composed of cuprite (Cu₂O), occasionally mixed with thin layers of tenorite (CuO) or surface carbonates. Red Patina marks a transitional oxidation phase between bright copper and darker patinas.

CENT #4075 – Red Patina notable threshold — CENT #4075 – Notable red (minimum)

CENT #9507 – Significant red patina — CENT #9507 – Significant

CENT #9427 – Full red patina — CENT #9427 – Full red

Red Patina Tonings

Intensity Scale

Notable red: Isolated but clearly visible reddish films or blushes, often in selected fields; roughly from the minimum threshold up to ~20% of the surface area.
Significant red: Red patina is a major visual actor, with uneven but strong red toning across multiple zones; approximately ~20–70% coverage, or a smaller area with particularly saturated red chroma.
Full red: Red tonality is the dominant surface condition with coherent continuity across the coin; generally > ~70% coverage, reading as a clearly “red” cent at first glance.

Version 1.1 – updated to notable / significant / full scale