A06_02

The Common Thread: Authenticating a Nazca tunic using combined dye analysis by LCMS and radiocarbon dating on a single fiber

Hendriks L¹,  Haghipour N^3,4, Chen V², Holden A², Smith G²

¹School Of Engineering And Architecture Of Fribourg, Switzerland, ²Conservation Science Laboratory, Indianapolis Museum of Art at Newfields,, Indianapolis , USA, ³Geological Institute, ETH-Zurich , Zurich, Switzerland, ⁴Laboratory of Ion Beam Physics, ETH-Zurich, Zurich, Switzerland

Accessioning historic textiles into museum collections often requires objective information regarding the object’s appropriateness and authenticity before being accepted.  In the case of dyed fibers, evidence of period appropriate dyestuffs builds confidence and reduces the chances of the object being a simple fake produced using modern materials.  Increasingly, objective age estimates in the form of radiocarbon (14C) dating are needed to further prove that the naturally occurring materials match the purported date of the textile.  Each of these techniques are destructive requiring a small sample of the object, and are typically conducted separately by different laboratories on individual samples. 

In 2020, the Indianapolis Museum of Art at Newfields sought to acquire a Nazca dyed camelid wool tunic dated to the period 100 BCE – 600 CE.  Because of the supple feel and excellent condition of the artifact, concerns were raised over its purported age.  Museum curators and conservators requested an investigation of the object’s materials. This report demonstrates for the first time the sequential, combined analysis of dyes by liquid chromatography-diode array detection-mass spectrometry (LC-DAD-MS) and subsequent ¹⁴C dating of the same extracted fibers.  Reusing the extracted fibers for radiocarbon dating reduced the risk of additional damage to the textile. The analysis confirmed that the wool fibers were dyed with common Peruvian dyestuff (indigo blue, purpurin red, quercetin yellow) and the ¹⁴C results placed the object between 550 and 650 CE.  Based on these confirmatory findings, the Nazca tunic was accessioned into the collection in 2021.