Simple Explanation (ELI5)

Think of it like cataloging the colors of a painting without ever touching it: scientists use a portable 'light camera' that reads colors the way our eyes do, but instead of a flash, it measures reflected light. This helps them discover that red and white dominate the ancient rock paintings in the Andes, as if they were the favorite colors of ancient artists.

Key Advantages & Current Limits

🟢 Pros: Non-invasive analysis keeps the paintings untouched, enabling repeatable studies over time and the creation of digital maps for conservation. 🔴 Cons: The complexity of the rocky substrate and the age of pigments can introduce measurement variations, requiring integration with other technologies to confirm results.

Future Outlook & Takeaways

In the coming years, this method will be extended to other Andean sites, enabling global comparisons of pre-Columbian painting techniques. Additionally, the collected data will help develop automated systems for monitoring color erosion, crucial for saving this cultural heritage threatened by climate change.

How Are the Hidden Colors of Cusco's Rock Paintings Revealed?

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In the heart of the Peruvian Andes, at Tecsecocha, Ccorca, ancient rock paintings tell stories of people and camelids. To study their colors without touching the artworks, researchers used a portable device called Capsure by XRite. This gadget, similar to a tiny scanner, measures reflected light between 400 and 700 nanometers, delivering an NCS color code—a universal language for describing visible shades.

The findings reveal that white and red dominate the palette, but with many variations. The most common codes, S2030‑Y70R and S3010‑Y40R, indicate yellows heavily tinged with red (70% and 40%). In anthropomorphic figures, the red proportion shifts slightly, suggesting ancient artists adjusted pigment intensity per figure. For camelid depictions, tones range from S3005‑Y20R (yellow with little red) to S2030‑Y70R (yellow with strong red influence).

This analysis requires no physical samples, keeping the paintings untouched. The method opens new ways to compare painting techniques across Andean sites and to understand how ancient peoples perceived and mixed colors. In the future, these data could help monitor color erosion caused by environmental factors, preserving a unique cultural heritage.

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Color spectrophotometry relies on Lambert‑Beer’s law, linking light absorption to pigment concentrations. For rock paintings, the heterogeneous stone substrate poses a challenge, as it can scatter light unevenly. The Capsure device employs a calibrated LED light source and a full-spectrum sensor to capture the surface’s spectral response. Raw data are transformed into NCS (Natural Color System) coordinates, describing hue, chroma, and blackness.

Codes S2030‑Y70R and S3010‑Y40R represent yellow hues with 70% and 40% red influence, with NCS chroma values of 30 and 10, respectively. These variations may stem from pigment chemistry (e.g., red ochre vs. white gypsum), particle size, or the amount of organic binder used by ancient painters. Moreover, pigment–rock interactions can cause ion migration, subtly shifting perceived colors over time.

The non‑invasive approach enables high‑resolution digital color maps, suitable for statistical comparisons across archaeological sites. Multivariate analyses (PCA, clustering) can reveal tone groups linked to specific cultural phases or pigment preparation techniques. Combined with archaeometric data (radiocarbon dating, isotopic analysis), these insights enrich reconstructions of pre‑Columbian artistic practices and guide targeted conservation strategies.