Spectroscopies at E-RIHS lab in Ljubljana

The last laboratory I visited as part of the “Meaningful Materials in the khipu code” project was the Heritage Macromolecular Laboratory: a joint laboratory between the Institute for the Protection for Cultural Heritage of Slovenia (IPCHS) and the University of Ljubljana.

Accessed through IPERION-HS funding, this laboratory is also among the foundational pillars of E-RIHS. Unlike IPERION (which operates as a network, as a consortium) the upcoming E-RIHS will operate as a proper European Research Infrastructure for Heritage Science.

From left to right, top to bottom: Lucrezia Milillo, Marei Hacke, Lea Legan, Klara Retko, Polonca Ropret in front of the entrance of the laboratory, already displaying the E-RIHS plaque

Here, together with the heritage scientist Marei Hacke, we brought khipu samples to refine and expand our understanding of khipu colours through Raman Spectroscopy and Surface-Enhanced Raman Spectroscopy (SERS).

Marei Hacke preparing khipu samples for Raman Spectroscopy

Even though Liquid Chromatography is the most efficient option for knowing which organic dye has been used, it can be time-consuming; while Raman and SERS have a better ratio of sample quantity/successfulness of the analysis compared to chromatography and are quicker. This means that also one tiny hair is sufficient to obtain a spectrum whether it is an organic dye or an inorganic pigment.

Dr Klara Retko is an expert in the optimisation of the Surface-Enhanced Raman Spectroscopy for the characterisation of organic colourants present on cultural heritage objects. For this reason, it was a great opportunity to have her analyse khipu dyes with Raman and SERS.

The Raman analysis of khipu samples was paired with FTIR-spectroscopy performed by Lea Legan in order to cross-check data about dyes. However, FTIR was particularly useful to analyze khipu vegetable fibres whose nature is still obscure. These data will be also cross-checked with light microscopic and SEM imaging of these fibres, in order to shed light on another still obscure constituent of many khipus. FTIR as well requires a minuscule amount of fibre.

Working at the Heritage Macromolecular Laboratory in Ljubljana has been a great opportunity not only to obtain new exciting findings on khipu colours (which are going to be disclosed in a publication later on) but also for me to enhance my understanding of the very process of sampling. Experiencing the very practicalities behind these analyses, made me understand much better the fibre quantities required for different purposes.

Lucrezia organising the khipu samples in the appropriate bags and updating the project’s spreadsheet