The barbs that make up a feather vane have a series of microscopic hooks on one side
and eyes on the other. The hooks of one barb mesh with the eyes on the next.
The connection is what holds a vane together. These structures are more numerous and stronger on
the stiff feathers than on the softer contour feathers in order to withstand the rigors of flight.
Occasionally, the barbs separate and a split forms.
Carving a few of these adds greatly to the realism of your carving.
This is the method I use to create overlays on the major
flight feathers: primaries, secondaries, tertials and tail
First, sketch in the overlay. The dotted line illustrates how the barbs on the
lower portion of the overlay meet the barbs on the upper part. The shaded area
represents the outside of the vane in its "closed" (unsplit) state. This will
be carved away in the next step.
With a cone shaped diamond bit, carve away the darkened portion shown in the
previous photo. Carve straight down, creating a 90 degree ledge to the feather
below. Then carve a shallower ledge on the left side of the overlay
where it overlaps the vane below (indicated by the arrow).
This is a close-up of the initial cuts. This has not been sanded, so before proceeding to the next step, sand this area. Sand the bottom portion of the split (indicated by the green arrow)
almost even with the feather below. Do not sand the outside portion of the overlay (indicated by the black arrow) level with the feather below. We need that material to "lift" this portion of the overlay from the feather below.
Run an elongated diamond needle carver along the bottom portion of the overlay
indicated by the black arrow in the previous photo, "lifting" it from the feather below. You are creating a hollow area between the upper portion of the overly and the feather below it.
This is a close-up showing the undercut made with the diamond flame in the previous photo.
This is the completed overlay. The area that was undercut has been sanded to
a crisp edge, and the lower portion of the overlay has been sanded down to
almost level with the feather below. The area laying on top of the vane has been sanded
to a crisp edge, as well. The lines indicate the burning direction. Notice that the barbs
end at the EDGE of the overlay...not follow the outside curve. This is important. The ends of
the barbs form the edge of the feather, just as they do on a "closed" vane. The barbs don't
lengthen - which would be the effect of burning them to follow the outside curve.
