Today, there is an extreme scarcity of knowledge regarding not only “where” khipus are from, but also “when”. We lack the archaeological context of most of them and of 12 hundred khipus recorded so far, only forty-ish have been radiocarbon-dated.
C-14 dating is not self-sufficient in providing answers to khipus’ temporal origin given the very short time-lapse the Inka empire has been ruling for. However, it is still an essential and large contribution to our understanding of khipus if correlated with morphological and archival information.
From June 27 to July 7 2022, as part of the IPERION-HS project, I was a guest in Florence at the Italian National Institute for Nuclear Physics (INFN) section Cultural Heritage Network (CH-Net).
Here, I collaborated with Mariaelena Fedi (head of the AMS C-14 section), Serena Barone and Lucia Liccioli to radiocarbon date five samples of Andean khipus (also part of the wider research project).
All the samples but one had already been prepared in cathodes for being allocated in the Accelerator Mass Spectrometer (AMS) carousel. Fortunately, I could attend and partially participate in the graphitization of the last sample I brought with me to Portsmouth from Gothenburg.
Serena Barone (left) and Lucia Liccioli (right) preparing the the last sample to be “cleaned” from all impurities and contaminations 
Khipu sample after being cut in small pieces immersed in a solution to remove impurities 
Serena Barone in the process of graphitization 
Serena Barone pouring liquid nitrogen for the graphitization process
After graphitization, the sample becomes literally a piece of graphite (only the Carbon atoms of what composed the cotton samples are left). The piece of graphite is encapsulated in a cathode made of aluminium ready to be placed in the AMS’s carousel as portrayed below.
The measurements can be really time-consuming even if letting the AMS work day and night. This was a great time to have a tour of the laboratory, to know the projects they are involved in, and to understand more about the very practicalities of C-14 dating.
The C-14 team has been incredibly instructive and communicative in keeping me updated with everything that was going on and also had astounding patience in explaining to me how AMS C-14 works, how they organize data and how to evaluate results.
During this time I was also able to structure a presentation I then gave to the whole INFN CH-Net team on the last day. This was a great opportunity to give back to the team the importance of their contribution within the broader picture of khipu research. Having feedback from an audience of researchers and professors specialized in physics was a great opportunity for me to enhance and expand my communicative skills and my views about the broader khipu research.
Lucrezia Milillo 