Dab a moist Stubble Sponge into black Grimas Water Make-up (Pure). Hold the Stubble Sponge between the fingers and compress it gently, so that it becomes a bit convex. Test the colour intensity on the hand first. Then work dabbing onto the skin: do not use a brushing motion, since you would remove the structured effect.
The shape, width and quality of the brush are to a great extent qualifying the effect you can achieve with it. For instance, round brushes are ideal for making curves and drawing curls. You draw straight lines preferably with a flat brush, keeping the handle of the brush pointed in the direction of the line. To draw a thin line, you do not necessarily need to use a narrow brush. You can also use the edge of a flat brush for that. This brush is also very convenient for making a thick line merge into a thin one, turning the brush on its side in one fluid action as you go automatically changes the line from thick to thinner. When you come to the end of a line, lift the brush from the skin in a single smooth movement.
Hint: to make beautiful, thin lines, you mix the Water Make-up with Cleansing Lotion instead of water.
You can create a beard shadow using a Stubble Sponge. 
