Green Approach of Charred Document Preservation using Sago Seeds and its Decipherment using OCR and VSC Techniques

Abstract

Polysaccharides are one of the most abundant natural polymers. The use of a natural polysaccharide in the field of questioned documents, particularly charred documents to stabilize and decipher the invisible content on charred documents, is a novel method. The present study focuses on the application of sago seeds to synthesize sago analog by reaction with glycerol in the presence of an acidic medium and microwave irradiation. The comparative spectral characterization (ATR-FTIR) of pure sago powder and synthesized sago analog confirmed the formation of ether linkages in the sago analog after the reaction. Further, the synthesized sago analog on application over fragile charred documents, charred at 300 °C, provided an appreciable strength to the coated sample in comparison to the non-coated charred sample. The bursting strength tester showed that the bursting strength of coated charred document (Linc Pentonic+75 gsm paper) increased from 0.12 kg/cm² to 0.19 kg/cm². Moreover, it deciphered the invisible and unreadable texts over charred documents to a remarkable extent. Additionally, the new optical technique of optical character recognition using Google Lens gave an advanced way of converting deciphered content from images into readable and copiable texts. The analysis of samples under the video spectral comparator (VSC) also showed an appreciably enhanced visibility of texts under flood light and white spotlight at visible range longpass (wavelength). Hence, this study provides an easy, cost-effective, and non-toxic approach to document preservation, decipherment, long storage duration, and future references in a court of law.

Keywords: Charred document, sago, OCR, Google lens, ATR-FTIR, Video spectral comparator.

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