Lightly rework all of the areas that you have already done to blend one tonal value into another. This is done with a medium to low-medium temperature setting.
The sides of the mouth on a cougar are white colored fur. So for this areas fine line shading turn your temperature setting to low. Work the fine line strokes starting at the outer edge of the mouth and pulling into the high curve of this area. By starting this same stroke along the whisker lines you can create the impression of fine whiskers without actually burning them.
The chin and jaw area are black brown where they are overlaid by the mouth. Otherwise this entire area is also a white fur area and burned on a low temperature setting.
Returning to a medium or medium-high temperature setting work the area of the skull in front of the ears, this is a dark tonal value area. Note in the back ear that the long fur lines do not completely fill in along the outer edge of the ear. Allowing a few open spaces in this area creates a more realistic effect.
Continue with the medium-hot temperature for the remaining foreground ear. Again, allow open, unburned areas in the long, inner ear hair spaces. In the foreground side of the face the fine lines are worked at a medium to low-medium temperature setting and less densely packed than the muzzle or eye areas. The areas at the far left of the face side are only defined by the short, dark strokes along the wrinkle lines.
Sign and date your work using a medium temperature setting.
Rework any areas that need strengthening. Check for even, smooth transitions in your tonal values and crisp, dark, solid areas of fill around the eye, side of the cheeks, back of the foreground ear, and nostril.
Lightly wipe the finished burn with a clean, dry cloth to remove any burning dust. Using a white artist’s eraser clean the entire surface of the burning, working with the grain of the wood. Remove any eraser dust with your cloth.
Seal your work with two to three light, even coats of acrylic spray sealer.