@spikeyxxx It was unclear to me why I need a color ramp for this to work since the noise pattern with it’s greyscale value (and black and white as the two extremes) could already define the brush colour opacity.
In the meantime, I’ve tested the behaviour since I couldn’t find any description in the Blender manual (right click on the colour ramp check box and selecting “Online Manual” only directs you to an overview page for the different procedural texture types):
The colour of your brush acts as a filter for the colour ramp gradient so that you simply need to set your brush colour to white in order to get the exact colours from the colour ramp since white contains all three primary colours. Therefore, using black as brush colour will result in a completely black stroke no matter which colour you choose for your colour ramp.
