In fine sewing, the inside of the project is as important as the outside. Even if you’re not that concerned with how the inside looks, finishing seams is important for other reasons.
A finished seam will help to define the project’s shape, increases durability, stops edges from unraveling and will make your project something to be proud of.
There are many types of seam finishes. Some of them are very quick and easy and others can take some time. Choose the one that will complement your project and suits the fabric. Always finish seams as they are sewn because they may cross other seams during construction.
The following descriptions include a cross section detail of one side of the seam allowance.
There are some fabrics that require no finish of the seam allowance at all, such as polar fleece and felt. Also, if you cut out your pattern so the edge is in the selvage, you would have no need to finish it. You’ll find this recommendation in some specialty books and patterns. Even if you don’t finish the seam allowance, you must be sure to press it. You’ll need to decide whether to press it open (flattest) or to one side.
This is the quickest and easiest finish, if you have a set of pinking shears (or scalloped rotary blade). Simply pink the edges of the seam allowances. Don’t use this on a fabric that unravels easily.
This is another quick finish. Run a row of zig-zag stitches along each seam allowance edge.
If you have a serger, you can run an overlock stitch on the edges. Some sewing machines also have an overlock stitch (although it’s not as robust). This is a 4-thread depicted, but a 2 or 3 thread is sufficient.
This is a hand stitched finish. Press the seam open and hand overcast the edges. You can also press the seams to one side and overcast both for seams that are not pressed open like an armhole.
Turned Edge Finish
This works for lightweight fabrics or an unlined jacket. Press the seam open and turn the edges under about 1/8” / 3mm. Sew with hand running stitches or machine stitch. Note that only the seam allowance is stitched.
This finish is somewhat bulky, due to the extra layers of the binding tape. You should use bias tape that is very thin. Wrap the edges of the seam allowance in bias type and sew them in place. Note that only the seam allowance is stitched.
Rolled Edge Finish
This is a good finishing option if you want to completely enclose the edges and make them invisible. It is best used on sheer fabrics. Join the seam in the usual way but don’t press it open. Trim the seams evenly and roll them up tightly. Sew over the roll inserting the needle under the rolled edge, not through it, as in a whip stitch. Pull up tightly to bind.
Strap Seam & Finish
This is used as a decorative tailored finish on unlined coats and jackets. Stitch a regular seam with the wrong sides together. This puts the raw edges on the right side of the fabric. Trim the seam allowances to 1/4” / 6mm and press open. Cut a bias strip of the garment fabric with edges pressed under. Place the strip over the seam and baste in place. On the right side, stitch each edge as close to the fold as possible.
Catch Stitch Finish
This is a very flat seam finish for wool, flannel, challis, etc. After the seam is complete, cut away one edge of the seam allowance to half its width. Press to the side with the longer over the top of the shorter seam allowance. Work a catch stitch by hand to flatten into position.