Step 9: Shading, part 1
First, decide where you want to shade (lion's mane). Second, determine how dark you want it to be and if you want to change the shading in different parts (gradient). For the question of how dark, i would say that the darkest should not cover up your basic and detail lines (picture 1).
How to Shade
Use the same nib that you used on for the lines (picture 2). I use the end of this nib which is flat and about 1 mm wide. Hold the pen like you would for a flat line and barely touch it to the top of the wood. While keeping it on the wood, move your hand in a circle, keeping the the nib at the same angle. You should notice the wood to start getting darker. Keep doing this until you get to the desired shade of wood.
Keep moving the nib, if you let it sit in one spot too long or favor one part of the wood over the other, it will show. If this happens, try to blend the darker parts into the lighter parts.