Just watched marathon Windsor and Newton. I love to see you do the swatching so I don’t have to! Why is neutral tint called that?

It's called neutral tint because it is used to tint other colors down and it should do this in a neutral way so the color shouldn't get cooler or warmer. Unfortunately I don't think it does that exactly, because it is a cooler color by itself.

Is there a positive tint and a negative tint?