With initial focus devoted to creating the iodine stock, it was found that only a negligible amount of iodine would dissolve in neat HFE-7100; enough to produce a pink colouration, but not enough to impart strong iodine development when that solution was applied to fingermarks. Both heptane and methylcyclohexane were previously used to solubilise iodine, and more importantly, these solvents are known to concentrate the iodine into fingermark residues (e.g. Fig.