Create the Grain Lines
Dip the tip of the fan brush into black glaze, wipe some of the excess on paper towels, and blot the brush on a dampened sponge to spread the bristles. Lightly drag it along the surface to create delicate grain lines.
A slight increase in pressure on the brush will intensify the color. Create straight lines at a slight angle to the sides of the piece, as mahogany is generally cut on an angle, or create U-shaped areas to mimic hard grain.
Immediately after brushing on each length of graining, soften the graining by dragging a soft blending brush over the lines created by the fan brush. Allow to dry.
For added protection on surfaces that may undergo constant wear, add a water-based acrylic sealant.