All Reference Home Office Fingermark Visualisation Manual Fingerprints and Other Ridge Impressions When replicating the developers described by this work, one should ensure that the iodine is fully dissolved in heptane prior to adding any HFE-7100 to guarantee its solubility. After dissolving in heptane, the iodine remained stable in solution for up to three months; however, this was no longer the case once HFE-7100 was added. Similarly, when making up α-naphthoflavone solutions, the α-naphthoflavone should be completely dissolved in dichloromethane prior to adding the HFE-7100 to ensure solubility. The α-naphthoflavone stock solution was then stable for up to six months, although losses of volatile solvent may lead to precipitation.