Before Arsenic: Recovering a Forgotten Indian Technique of Painting with Indigo and its Implications for Knowledge Transfer.

This article challenges the prevailing historiography, which asserts that painting with indigo on cotton was technically impossible until the British innovation with arsenic trisulphide in the 1730s. By reconstructing the Indian indigo painting process from the Beaulieu manuscript, the study demonstrates that European dismissal of fermented coconut sap as a viable technique stemmed from a lack of understanding and the incompatibility of the Indian technique with capital-intensive production models. Painting with indigo was not a technical impossibility but an economic and artisanal problem, requiring specialized knowledge of fermented coconut sap's properties. The study argues that successful knowledge transfer depends on adaptability to environmental and structural conditions, advancing a broader definition of "useful knowledge" in global economic and technological history-one not limited by immediate economic applicability.