Purpose This paper aims to discuss the use of the sensor material in coating to detect defects which can cause corrosion on metal substrate. This coating consists of sodium polyacrylate (SP) to detect the presence of water and fluorescence substance 2-[4-(piperidin-1-yl)-5H-chromeno-[2,3-d]pyrimidin-2-yl]phenol [benzopyranopyrimidine (BPP)] to detect crack formation. Design/methodology/approach The coating resin is a mixture of poly(methyl methacrylate) (PMMA) and poly (methyl vinyl ether-alt-maleic anhydride). The additives are used to provide a visual indicator to the observer for when the coating exhibits any defects, so that quick action can be taken before corrosion develops further. SP has absorbent properties and expand when in contact with water, while BPP exhibits high luminous intensity in its solid form that is easily perceivable when exposed to UV. PVM/MA was used as the binder with ethanol as the solvent. The resistance of this coating towards water penetration was investigated using electrochemical impedance spectroscopy (EIS). The coating’s performance was observed in terms of visible optical appearance. Findings The sensor coating developed in this project serves as visual aid to the observer through the expansion of SP and high fluorescence of BPP material after the top coat is physically damaged. These findings are in provision of preventive measures that can be taken in case of top coat failure. Research limitations/implications The resistance of the coating that contained SP could not be investigated with EIS due to its ability to expand immediately when in contact with liquids. Practical implications The coating developed in this study may be to detect corrosion. Originality/value The sensor material used has not been previously studied in applications to detect the presence of water or used to detect crack formation.

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