I want to teach you how to alter a garment that has French Seams in it.
But, first, I’d like to talk about what they are and how they are made.
The French Seam is a seam that is encased within itself so that no raw edges can be seen.
You’ve probably seen French Seams on many types of garments including lingerie, bridal and even on fancy pillow cases.
I use them most often when making a “wrap” for a bride or a girl going to prom.
French Seams are often found on fabrics that are sheer like this blouse:
The photo above is taken of the right side of a blouse and the photo below is taken on the inside of the blouse:
French Seams are also found on garments where the fabric frays easily.
They are generally sewn on seams that are straight.
It’s very difficult to make them on a curved edge like a sleeve or princess seam.
But they are perfect for side seams and shoulder seams.
Let’s take a look at how they are made.
I found a scrap of sheer fabric:
The main point I want to emphasize here, is that the consruction of a French Seam is different than that of a regular seam.
In this case, to sew the seam, you will put the two pieces of fabric wrong sides together!
Stitch that seam with a 3/8″ seam allowance.
I used a contrasting bright pink thread so that you can see it better:
Trim the seam to a scant 1/4″.
“Scant” means that the seam allowance should be a little less than 1/4″ wide after you trim it off.
You might feel more comfortable trimming with scissors.
Here, I used a rotary cutter and mat to do the job.
Next, press the seam open.
Be careful not to scorch the fabric.
Some fabrics are not to come in contact with an iron.
They might melt.
In that case, just “finger press” the item by pushing it down with your fingers and running your fingernail on the seam to help it lay flat.
Next, fold the fabric so that the seam allowance is on the inside and press close to that edge. Again, you can finger press if you can’t use an iron.
You want the stitches to be on the very edge, not going toward one side or the other:
Make sure you trim off any frayed edges along the seam allowance.
This is a very important step. If you don’t do it, you’ll risk having lots of wispy “whiskers” sticking out after you sew the seam.
Now, stitch using a 1/4″ seam allowance.
Press the seam to one side or the other.
Ok, now let’s alter a garment that has French Seams.
Whatever amount you need to take in, is the amount you’ll need to trim off the raw edge of the fabric.
For example, let’s say you need to take in 1/2″ all the way down the side seam of a blouse.
I would open up the French Seam all the way (From armpit through the hem) and press the seam flat.
Then, trim off the 1/2″ off the raw edge of the seam.
Then, referring to the instructions above, put the seam back together wrong sides together first.
Follow the rest of the instructions above.
What if you don’t need to take in that much all the way down the seam?
Let’s say you need to take in 1/2″ under the arm and then taper it to nothing, seven inches below the underarm.
Then, just rip out about 9 inches (or whatever you need to have room to work) of the seam, press it flat and trim off the amount you need to take in.
Then put the seam back together again.
It’s the same procedure for any French Seam.
Before you begin, just be careful to do the math and check it twice before you begin!