This is one for you if you’re feeling a little lazy. You could do this demo and explain the science yourself… or you can let Dr Andrea Sella of the UCL Chemistry Department explain why things appear “white”. Suitable for anyone teaching the electromagnetic spectrum or “properties of light” at KS3 or KS4. (Warning: the first few seconds of the video are deliberately meant to show a blank white screen).
...so, especially after the previous entry about the Black Scientist, I can not help but think "so what's the blackest material, and blackest black". In fact, generally, what makes a colour the most intense of it's frequency.