colour blending option won't turn off?

[Enug]

Kate if it's any consolation I too have to paint on a new layer when I add another colour when using the airbrush. If I don't the tool won't add a colour at all or it's not the shade I want. Even then I will find that blending a light colour on a layer over a black layer will give me a 'fringe' of undesired colour.

Two layers here.

[mikahawkins1]

@markw Thanks for explaining the difference.