If you like to paint watercolor,
you should know what I'm talking about.
Neutral Tint. What MSG is to food, this would be its equivalent in a paint tube. All it does is it simply takes your current pigment and makes it darker without the jarring effects of simply mixing a color with black. But once you use it to punch up your painting, be careful, because it's so easy to get carried away with it; and before you know it, your painting will be too dark and overworked. It's like a liquid cheat code. This stuff is highly addictive.
And I love it.
Always have it on your palette. But, to be safe, I'd place it in the corner, away from all the other colors.