Fingermarks placed on paper were next assessed using the all-in-one iodine α-naphthoflavone spray but were found to yield unacceptable levels of blurred detail (Fig. , top). We postulate this was caused by the iodine α-naphthoflavone chromophore being wicked from fingermark residue into the surrounding porous cellulose structure of the paper, solubilised by the blending solvents.