Create
the button placket. You need 2 strips (one for
each side) of linen or silk that are 1" longer than your lacing
placket and 2" wide. The length is determined by how
many buttons you wish to use. There is evidence for
as little as three and as many as, well, from your
wrist to your shoulder. The color can match or not,
there is not enough evidence to say if there was
preference.
Sew the strip to the
right side of the front piece using a running
stitch.
Fold the strip so that it now is on the wrong side and sew down
the facing at the edge using the running stitch.
Turn under the raw edges of the strip and sew them down
using the running stitch. You might want to use pins
to make sure that the facing and the outer fabric lie
flat together, especially if using silk. I prefer linen
but what little facing info we have from period is silk.