This talk will trace the history of a recipe for sunscreen, made from olive oil and mastic gum, to consider the fugitive nature of recipes as historical texts. There are many thousands of extant medicinal and cosmetic recipes from early modern Italy – the period where I can claim some expertise – but in what way are they ‘from’ this period or place at all? This remedy was translated into Italian in a 1562 book from an earlier sixteenth-century Latin translation of a sixth-century Byzantine text, that itself was likely copied from an ancient Greek source. An almost identical remedy was, from the fourteenth century, described as ‘oil of Mesue’ – a medication that was in use until at least the 1670s and may be based on an earlier, lost, Arabic recipe – but, despite apothecaries’ attempts to find an ‘authentic’ version, was subject to so many tweaks and variants that it is impossible to make out any original instructions through subsequent iterative layers. When, in 2022, the ‘Renaissance Goo’ project reconstructed the 1562 recipe in a soft-matter physics lab, whose recipe were we making? Can this type of reconstruction ever tell us anything about history, and if so, how? To aid discussion, I will bring along some samples of the ‘sunscreen’ for audiences to experience at first hand.