A French seam is a type of sewing seam in which the raw ends of the fabric are tucked in, leaving a clean, polished, professional look. In addition to looking tidier, a French seam also protects delicate skin, and it prevents raveling of the fabric. Many seamstresses use French seams on lightweight fabrics, and these enclosed seams are relatively easy to create once one gets the hang of it.

To sew a French seam, the seamstress starts with the right side of the fabric facing out, and sews the seam along the desired edge. Then, the seam allowance is closely trimmed so that a minimum of fabric stick out beyond the stitches. Next, the fabric is opened and then folded together with the right sides facing in, and another seam is sewed in close proximity to the first seam, neatly enclosing the ragged edges of fabric inside the seam. Typically, a French seam is then pressed to lie flat in a particular direction, and after that, the seam is finished.

Because a French seam is entirely concealed, the technique can be used when threads would distract from the integrity of the design, or on lightweight fabrics which might ravel easily without reinforcement. The double layer of stitches protects the fabric and hides contrasting thread very well. In addition, there are no trailing threads or ragged edges to irritate the skin, a trait which can be very useful on garments worn close to the skin.

When sewing a garment with a French seam, remember to include the larger seam allowance required for a French seam when you cut the fabric for the garment. Since the seam is sewn and then doubled back on itself, it will require a wider margin than some other seams. You may also want to start with straight French seams before plunging into hidden seams on curves such as sleeves, as these curved seams can be challenging.

When purchasing clothing, a French seam is often a sign of good quality and careful construction. Make sure to inspect the seam closely to ensure that it is tight and even, and look for signs of puckering or gaps along the length of the seam. You may also want to pull gently on either side of the seam to make sure that the fabric does not tear or separate. These inspection techniques should be used on all garments before purchase, as seams are the first line of failure on cheap clothes.