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The use of seaweed as fuel has been mentioned in ethnographic and historical sources of different coastal regions. Nevertheless, the archaeological record of seaweed burning is still limited to contexts where preservation is exceptional and macroscopic discrimination of charred remains is possible. Here, we evaluate the effectiveness of Raman spectroscopy in discriminating seaweed vs. plant/wood char. Our dataset (N = 92) consists of modern and archaeological seaweed and plant/wood charred remains, including specimens of unknown origin from the Atacama Desert coast, Northern Chile. The charred samples were processed to obtain 13 parameters which were then fed into five supervised machine learning models. The models, built on samples of known origin (seaweed and plant/wood), performed remarkably well in terms of accuracy, kappa, sensitivity, and specificity. The models were used for final predictions on 10 non-identified archaeological charcoals. Our results suggest that Raman spectroscopy combined with machine learning techniques is a robust methodology for discriminating seaweed and plant/wood charred remains in the archaeological record. The predictions on unknown samples confirm that seaweed was used as fuel in a specific funerary ritual in the southern Atacama Desert coast around 5000 cal BP. Furthermore, charred specimens of Lessonia spp. recovered from combustion features in other northern Chile coastal settlements, suggest that seaweed pyrotechnology developed by Atacama Desert coast people is likely a long-term process. As for coastal archaeology, this work encourages new research on seaweed as an alternative/main fuel in coastal deserts and evaluates possible bias for chronologies from coastal archaeological settlements around the globe.

[ES] En este estudio se realizará una comparativa de los moldes utilizados para el proceso de termo-conformado, uno mecanizado en aluminio por fabricación CNC y otro fabricado mediante tecnologías aditivas en ABS CG 28 . El objetivo principal es conocer cuáles son las ventajas y desventajas del uso de la impresión 3D para la fabricación de moldes para termo conformado y como el uso de esta novedosa tecnología podría beneficiar a la empresa para los servicios que ofrece actualmente a sus clientes., [EN] In this study I m going to make a comparison of the molds used in the process of thermoforming, one mechanized in aluminum by CNC manufacturing and other made by FDM (Fused Deposition Modeling) in ABS CG 28 . The main objective is to know the advantages and disadvantages of using 3D printing in the manufacturing of thermoforming molds and how the use of this innovative technology could benefit the company in the services they currently offer to their clients.