How to color an image with black without losing texture or detail

Question

I am becoming quite adept at using gimp but i'm still learning. When using pencil brush or airbrush by changing the mode from normal to hue or color I am able to change a color to another without losing any texture or detail. The problem that I am having with this is that I cannot do this method with black or white, while trying to use either it only paints over the previous with gray. I will try to add a photo example to show what it is i'm talking about.

The top line is done with red in color mode. The middle line is done with red in hue mode. The bottom area is black in color mode and black on hue mode has no effect. I would greatly appreciate any tips that would help me with what I am wanting to achieve.

Answer 1

You cannot color a black area using the color blending mode and see a noticeable difference. The top color layer will keep its color and will blend with the luminosity of the bottom layer by changing the hue and saturation.

See the below gradient.

The green on the left doesn't change much because the luminosity on the base layer (below the green color layer) on that side is too dark.

Answer 2

Set the foreground color to 50% gray, and the brush mode to multiply to darken and divide to lighten. See the two additional strokes in the picture.

You can of course use other shades of gray, or change the brush opacity. You can also paint in "normal" mode on a layer that you put in multiply/divide mode.