Nacre　is　well-known　for　its　unique　properties　due　to　its　＇bricks-and-mortar＇　structure.　We　employed　this　biological　paradigm　to　fabricate　nano-laminar　coatings　with　controlled　arrangement　of　montmorillonite　(MMT)　nanoclay　sheets　and　polyvinyl　alcohol　(PVA)　polymer　binders　by　a　self-assembly　process.　The　abundant　inorganic/organic　interfaces　were　demonstrated　to　play　critical　roles　in　enhancing　charge　dissipation　laterally　on　the　insulator　surface,　so　that　the　surface　charge　accumulation　is　suppressed　under　dc　stress.　Moreover,　the　stacking　barriers　help　to　protect　insulator　surfaces　from　hot　electron　bombardment,　inhibiting　further　electron　avalanche.　In　this　manner,　the　flashover　strength　of　the　insulator　is　improved　by　18%.　This　strategy　is　practical　and　scalable,　allowing　for　industrial　applications.　©　2019　The　Royal　Society　of　Chemistry.