The majority of shoulder straps were hand-made of bullion embroidery. This was time consuming and required a highly skilled craftsperson. During the Civil War mixing bright bullion, which was straight and bent in a series of angles to catch the light, and dead bullion, which is coiled, was a common way of making the border. The bright bullion appears as an accent mixed into the more common dead bullion of the border and bars. First lieutenant's bars on shoulder straps were always gold during the Civil War. The blue velvet of this strap appears somewhat dark in this image, but is not as dark as a typical staff officer's strap.
This is a metallic false embroidered strap (Smith's Patent). Smith received his patent on June 18, 1861 and large numbers of these straps were produced during and after the Civil War. The blue of this infantry strap is a little more intense than is typical. The borders of these straps are occasionally excavated from Civil War sites. Metallic straps could be produced much faster than bullion embroidered ones and held up better in the field. Notice that a effort was made to simulate the two types of embroidery on the border and bars. The strap curves to fit the shoulder. These straps are sometimes marked on the back.