Each etching is unique, as the colour treatment of the 48 spots is different in every print. Here, Hirst extended the simple rule, that no colour must appear twice in any work, by a second rule – that no two prints from this edition should be the same. Oleoylsarcosine was proofed and editioned by Peter Kozowicz at Thumbprint Editions using one plate. Oleoylsarcosine is one of a number of fatty acids used as ingredients in personal care products. As with the unique butterfly etchings, each print is marked with a unique Hirst reference number on the reverse.