Another experiment - I wanted to see what would happen if I shot a white flower with an IR camera whether it would be white on white or not. My garden is currently being taken over by bindweed so here they are, weeds in infra red.
Did you bring the highlights down at all? Wondering if it is a case of "blinded by the light" when you shoot pure white in IR! Smiled at your bindweed in the garden - oh so familiar!