When is a seam really not a traditional seam? When it sewn edge to edge. This is called an abutted seam. The edges are abutted and the adjacent pieces are sewn together.
Abutted seams are flatter than a traditional seam with underside seam allowances, and they’re often used in lingerie or when working with any number of fabrics that don’t ravel like dense wools, laces, suedes or leathers (faux or real). They’re also used on interfacings where flat is of the utmost importance inside a tailored garment. Quilters use abutted seams to sew batting together, either for re-purposing scraps or to extend the size of batt for an oversized quilt.
For the flattest seaming, trim off the pattern’s seam allowances from the pieces to be joined. Use a rotary cutter for a clean, smooth cut.
To sew an abutted seam quickly and easily, place a piece of sheer fusible interfacing tape or stabilizer adhesive side up and lay the two adjacent pieces edge to edge. Fuse in place to hold them while stitching. Note that it is possible to sew this seam without using anything underneath, but keeping the adjacent edges aligned and unstretched as you sew is more challenging.
Set the machine for a zigzag, three-step zigzag, overcast or other decorative stitch that’s wide enough to securely catch the abutted edge of both pieces at once.
The thread choice for seaming will determine how prominent you want the joining to be. Stitching can be done in a matching color to blend or in a contrast so the seam becomes a design feature. Use Coats Dual Duty XP Heavy for a prominent stitching line, or All-purpose thread for a less visible joining. Even Coats Tri-lobal Embroidery or Coats Metallic threads can be used to add a little pizzazz to the seaming.
If you want to create an abutted seam on a fabric that ravels, then press under the seam allowance edges first and join the folds in the same manner described above. Once the seam is sewn, the underside seam allowances can be trimmed to reduce bulk.