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, haute couture, and even on fancy pillow cases.
They are beautiful!
And they are not difficult to master.
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.
But you will find them in the curve of a sleeve as well.
I will be showing you how to do them on a straight seam (which will remind you of side seams and shoulder seams), but just use the technique on your curved seams and they should work very well.
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 construction of a French Seam is different than that of a regular seam.
In this case, to sew the French seam, you will put the two pieces of fabric wrong sides together!
Stitch the seam with a 3/8″ seam allowance.
I used a contrasting bright pink thread so that you can see it better:
Once you stitch the seam, 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.
My scrap piece is like that. It has some metallic in it and some beads, so I’ve got a option other than an iron to use for it…
In this case, just “finger press” the seam 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.
Here, I used an iron because the inside of the seam won’t show. I’ve set the iron on a rather cool setting so there isn’t a chance of it melting.
You want the stitches to be on the very edge of the fold as you press it, 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!
I am in a dilemma with a bride’s maid dress with french seams on the over skirt. The gal ordered a size 10 and needs a size 14. I have enough fabric, from the tail of the skirt that had to be shortened, to sew a piece (1 & 7/8″) into the side seams. I am going to use a long triangular piece but I cannot figure how to incorporate that triangular piece using a french seam. Here you cover how to take in a garment. I need help! If you can provide it, I would greatly appreciate it.
You are right, this is a dilemma! But, I’m so glad you have enough fabric to add a gusset. In this case, doing a French seam would most likely be impossible. So, go ahead and do the alteration. I know it means that you’ll have to take out more of the seam than you would normally, but it should be doable. Also, don’t worry about how it looks when you transition from the French seam to the regular seam. It shouldn’t show, but you may need to clip the seam allowance at that spot to make it lay flat. Depends. See if it lays flat first and then clip if necessary. If you have a serger, I’d use that to finish the seams when you are done with the alteration. I hope that helps and encourages you!
Ugh, I have the exact same problem, enough flat seam on the lining, but a French seam on the chiffon over skirt! Not a very good design to begin with! But, I will follow your direction, although I don’t need to let out this dress but 1″ on each side which = 1/2″, so I should be good. Although, the French seam on the over skirt will be narrow, have no choice! I think it will look o.k. UGH!