French Seams with a Side Vent

Yes, you can actually have a vent and a French seam at the same time!  I chose this mid weight cotton as my testing sample. This is a wonderful seam finish for light weight linen, cotton and sheer fabrics. Avoid loosely woven fabrics. An open weave will result in a hole in the area of transition.


This second sample at the right is sewn with matching thread. Take note how the END of the FRENCH seam tapers into a CURVE !



 I also used a pencil on the fabric for visibility.  You would substitute a water soluble marker or thread trace your lines. The thread trace is visible from both sides and will not damage any fabric. 
(Sometimes pencil will wash out.  Test first)


I used dark thread for better visibility.




A brief summary.... French seams are sewn with the WRONG sides of  the fabric together.  You stitch on the RIGHT side at 3/8". Trim the seams in half.  That means you will be left with a seam allowance between 1/8 and 1/4.   (That's 3/16" for those of us that still think in terms of inches.)  If you trim the seam allowance down to 1/8 inch it will be too hard to press the seam allowance open with the iron.  I don't care to burn my fingers!




Draw a line on the RIGHT side of your fabric where the French seam stops and the vent begins.  The vertical line I added helps you to stitch toward the intersection.   Yes, the line of stitching is taking a turn toward that point of intersection!  As you approach this intersection switch your stitch length to 1.0 stitch length rather than back stitching.  Back stitching tends to add too much thread.  Stitching in reverse often causes a pucker on sheer fabrics.
You can also use the tie-off knot feature on newer machines.  Do NOT use more than 3 knots or you will have a hard knot. I'm not really a fan of the tie off feature because it is more difficult to remove without damaging the fabric.













With super pointy tiny scissors (Gingher) clip a 45 degree angle to the intersection.

Always press the first seam open before you press the fold or your seam will not be exactly on the fold.  A Clover iron with a small iron shoe is helpful.  A Dritz or June Tailor wood tailoring board is very handy for this task.








Do NOT trim off the dog ears at the top of the vent.  This tiny corner will be folded under as you fold the vent seam allowances under.


The final line of stitching on the French seam is sewn 1/4 inch.  If you have a presser foot with the metal flange on the right hand side of the foot you will achieve straighter stitching lines. (foot #57 for Bernina)

As you approach the intersection where the French seam ends and the vent begins switch to a smaller stitch.

Do NOT clip off thread tails.  Leave about 3 inches. Use a needle to thread the tail and hide the tail into the seam.
This will prevent the seam from opening.
And it looks nicer!

Do NOT be tempted to use a Fray block product. They frequently are rough, crusty and visible on most fabrics.

 For the area where you have the vent opening simply fold and press the seam allowances under. Edge stitch the folded edge in place. Once again, a foot with a flange (center flange this time) will offer a straighter stitch.



This is a really clean way to finish off the side seams for those light weight summer tops !


Width of Side Vents:  You are NOT limited to using the 5/8 inch seam for the side vents.  The vents can be cut to any width of your choice.  A wider vent generally hangs straighter without twisting.