A significant chunk of the world’s history is facing an existential threat. US government deeds, recordings of Indigenous Australians and photographs of English seaside life spanning three decades are just some of the historical documents recorded on acetate film that are suffering irreversible damage due to what’s known as vinegar syndrome. (Pictured: Cellulose triacetate 16 mm film with severe vinegar syndrome, dated 1968. Ida Ahmad, Author provided