If you have done some altering and changing along the neckline and/or sleeve edges, the facing pattern that came with the pattern will no longer be usable for the changed neckline or sleeve. You will need to cut new facings that will fit the changed area, as shown in the following diagrams.
Cutting the neck facings
To illustrate the method of cutting facings, the above drawing shows a simple sleeveless, collarless blouse that will have a zipper in the back. Lay the paper pattern on the fabric. Cut along the outside seam lines. The facings will be cut from the remaining material.
In the above drawing the printed area indicates fabric and the shaded area indicates the areas where the front and back bodice have been cut from the fabric. The front and back bodices are the bodices previously cut out of the fabric and positioned on the remnants to indicate how to cut out new facings for the front and back neck. Be sure to put the center front neck on the fold and the back neck along the selvage edge, as was done with the bodices. after cutting the neckline and down 6 cm (2 3/8″) along the shoulder line, flip the bodice and fabric over and cut the neck facing 6 cm (2 3/8″) wide, as shown with dotted lines.
By making new facings for your altered pattern, you can be sure that the facings will fit the area, whereas the original facing in the pattern package would no longer fit an altered neckline.
Cutting the armhole facings
After cutting the altered front and back neck facings, the last step in cutting the blouse is cutting the armhole facings. The easiest way to cut armhole facings is to turn the bodices around and position the bodice armhole into the area of the cut out armholes as shown, and pin the bodice to the fabric. cut along the altered armhole edge and 6 cm (2 3/8″) along the side and shoulder edges, then flip the bodice over and cut the facings 6 cm (2 3/8″) wide as shown in dotted lines.
When altering a blouse, top or dress bodice, the advantage of cutting the front and back armhole facings separately is that they can be cut from small scraps, whereas one-piece armhole facings require a much larger piece of fabric.
This information is also in all of our Pattern Making and Pattern Changing classes on SewWithSarah.com.