A shoulder reinforcement is a piece of hair canvas or wool that is cut to fit the area between the shoulder and the bust (it's really the upper chest area). This extra piece helps to provide structure to the area, "filling in" any hollows and creating a smooth look to the front of the jacket. Patterns generally do not include a shoulder reinforcement piece, but it is really easy to draft. This tailoring book is a great reference, and includes a photo and directions on how to draft a shoulder reinforcement patch. Basically, you just have to take the front jacket interfacing pattern, place a piece of medical paper or tracing paper over the pattern, and follow the line of the shoulder, down the curve of the armhole, down the side seam for about 2 inches, curve toward center front and then back up toward the shoulder. The patch should be about 1/8-inch inside of the seam lines. The photo below shows the shoulder reinforcement patch that was machine-stitched onto the hair canvas interfacing for the jacket front.
After the shoulder reinforcement piece is stitched onto the interfacing, the entire front interfacing piece is hand-basted onto the jacket fronts. As you can see in the photo, the stitches are long and evenly spaced. Catch stitches are used at the shoulder and the side seams to securely attach the interfacing to those areas. The armhole and neckline seam allowances will be machine-stitched, as those areas will need stability.
Twill Tape
For tailoring projects, I use 3/8-inch cotton twill tape, not the polyester twill tape that comes folded in a little package. Cotton twill tape is sold by the yard, and is thicker than the polyester tape. For tailoring, the twill tape is used to provide structure at the lapel and the jacket front edges, so it is important that they are substantial. I always preshrink the twill tape before using it by soaking it in hot water and letting it air dry, then running an iron over it to smooth it out. The Sparkly Tweedy Jacket doesn't have a lapel, but I do need to tape the front edges.
The stitch I like to use is a simple basting stitch on both sides of the tape, as shown in the photo above. It is quick and easy and secures the tape to the jacket. One caution: it is important to keep the tape outside of the seam allowance --- the basting stitches are a good guide, but I also measure the seam allowance periodically as I'm stitching to make sure there is enough space for the seam. For this jacket, I just had to baste along the front edges of the jacket fronts, from neck edge to top of the hem. Easy!





