Penny Muncaster-Jewell gave a demonstration of the various types of seams and seam finishes to the Wonderful Wearables ASG group. She made samples of all the seams and brought in some of her beautiful art garments to demonstrate them.
The seams were:
1) Regular 5/8" seam: If the seam is curved, clip it so it will lie flat. Louise Cutting recommends cutting each seam at opposing 45 degree angles.
2) Top stitched seam: Sew a regular seam, press flat and then press open. Topstitch down each side to hold the seam flat. Use for fabrics that don't press flat well or fray. Use an edge stitching foot and needle reposition to get the same distance on both sides.
3) Overlapped or Butted seams: Use when pieces are already finished or the fabric doesn't fray like felt or ultrasuede. Use only a 1/4" seam allowance to reduce size of overlap. Use straight stitch or decorative stitch. Use edge stitching foot.
4) Edge to edge seam: Use when the edges or finished or do not fray. Butt the edges together using the edge stitch foot. Use a zig-zag or fagotting-type stitch to join. Penny showed us a combination of five straight stitches and then 3 bar tack stitches (that she put into her machine memory) and the seam looked like beading. She did this on a Diane Ericson pattern.
5) French seam: Useful see-through fabrics such as organza or fraying fabrics. First sew the seam WRONG sides together with a 3/8" seam. Press flat. Very accurately cut then seam down to 1/8". Fold over wrong sides together and press or finger press with a fold tool or sharp point to make the seam sharp. The raw edges are now inside. Sew a 1/4" seam. Some people prefer to press the seam to one side and then topstitch in place. This seam is difficult to do on curves such as armholes. If you use it, press to the larger section and ease in.
6) Flat Fell seam: A french seam used for Jeans. Sew the pieces WRONG side together. Use a 5/8" seam for regular fabrics or a 3/4" seam for thick fabrics. Trim one of the seam allowances to 1/4 inch. Press flat and then to one side. Fold the larger seam over the shorter one to the seam line and press. Stitch in place. The seam is on the right side of the fabric. Use edge stitching foot to keep stitches even. The mock french seam is when you sew the first seam Right sides together.
7) Pojagi seam: These were the tiny french seams sewn by hand in the 14th century used on Korean wrapping clothes call Pojagi. If the french seam was sewn down it was called a Tagi. Penny learned this technique from Jack Brockette. The key is to use Faultless Lemon Scented Profession Startch - the lemon makes a difference! Place the fabrics wrong sides together or a towel on your ironing board. Spray liberally with the starch and let it dry. Sew the 3/8" seam allowance and trim with a rotary cutter to about 1/8". Fold over and sew just slightly larger than the cut section. Press seam to one side. If necessary stitch a row of topstitching to hold the seam in place. Use edge stitching foot.
The seam finishes were:
1) Pinking: Remove only the smallest amount of fabric and cut very straight. Rarely used anymore.
2) Zigzag or straight stitch: Be careful not to pucker.
3) Overcast stitch on sewing machine
4) Serged: Use a 3 or 4-thread overlock stitch. If you are not positive about fit, sew the seams and then serge the edges. If fit is not an issues, serge seam and finish in one step.
5) Hong Kong finish: Use to add a pop of color to garment insides. Use organza or silk for trim if you like. Sew 5/8" seam right sides together. Cut bias strips approximately 1" wide. Stitch the bias trim RST to the seam allowance with 1/4" seam from fabric edge. Press the bias tape over the seam allowance and trim the seam allowance to 1/8". Fold the bias strip over the seam allowance and press. Sew in the ditch from the right side capturing the the bias layer underneath the seam allowance. You can trim the extra bit of seam allowance if you wish. Some people use old silk ties for this.
6) Hong Kong lining finish: For lined garments. Cut the lining piece 5/8" wider than the fashion fabric. Sew the seams WRONG sides together with a 1/4" seam. Turn and press sew that the lining fabric shows at the edge of the fashion fabric. This will look like a Hong Kong finish. Now sew the fashion fabrics right side together with a regular seam allowance. The key is accuracy in cutting and sewing the 1/4" seam allowance.
7) Bias Binding finish: Cover the seam allowance with seam binding, Seams Great, Seam Ease or other product and sew with a regular stitch to bind the edges of the seams, similar to Hong Kong finish.
8) Inside out seam finishes: For fraying fabrics sew the seams to the right side of the garment and allow to fray or do a Hong Kong seam on the outside of the fabric and stitch down when stiiching in the ditch.
9) Piping on the edge: Use corded or flat piping instead of a facing on a neckline or armhole. Attach with a serger or regular machine. Penny uses her serger to finish the edge of the piping.