Used to use motorbike visor stuff Bob heath or something like that when I was karting but that was 25 years ago. Once got some amazing wax like stuff from someone that was brilliant
Either anti fog spray solution or a pinlock visor or a double layered visor like the bell helmets have. Never steam up even in the middle of winter with a bell even with visor fully closed
Pinlock all the way. There is nothing to touch it as it creates a double glazing type insulating air pocket stopping your breath condensing on the inside when the outer visor is cold.
