Several studies have sought to optimise fingermark development methods based on combined iodine and α-naphthoflavone sprays. One of the first utilised an all-in-one spray using cyclohexane and dichloromethane as the carrier solvent, which showed clear visualisation for up to three-dayold prints, but was hazardous in terms of high flammability. This report was likely inspired by earlier work focussed solely on α-naphthoflavone developer sprays for iodine fuming. The allin-one iodine α-naphthoflavone spray was then refined using Arklone: a non-flammable, safer carrier solvent, however this was banned in the late 1980s under the Montreal protocol, prompting an investigation of alternate solvents, chiefly HFC-4310mee and HFE-7100, and Asahiklin AK-225 (HCFC-225). Asahiklin AK-225 was chosen by the Queensland Police Service as the carrier solvent for iodine α-naphthoflavone sprays in operational use, as prescribed by certain literature sources. However, like Arklone before it, in 2015 AK-225 was banned, leaving only HFC-4310mee as a potential alternative. Furthermore, past work found that blending HFC-4310mee with methanol improved fingermark contrast produced by iodine α-naphthoflavone sprays, however at a cost of increased background development on certain surfaces. In recent years the cost of this solvent has increased to approximately three times that of HFE-7100, likely driven by a 2018 phase-down in Australia, and elsewhere, of HFC solvents. This phase-down in HFC solvent manufacture, coupled with a gap in the knowledge for HFE-7100 solvent blends, mandates the evaluation of new alternatives by this work. This work seeks to identify a stopgap iodine-naphthoflavone treatment that can act as a substitute for AK-225, without utilising increasingly problematic HFC-based carrier fluids. Here, blends of HFE-7100 have been assessed with the goal of identifying an all-in-one iodine α-naphthoflavone spray that delivers equivalent effectiveness to the AK-225 spray. In addition, this study assesses the sequential application of HFE-7100 sprays of iodine solution and naphthoflavone fixative for porous surfaces, and provides an updated structural assignment of the chromophores, based on mass spectrometry evidence from the reaction.