How To Stabilize Seams Step By Step Tutorial

We have the garment cut, the matching thread ready in the sewing machine and our best footwear to step on the machine pedal. But, surprise ! when we go to join the shoulders we find that one is bigger than the other. We swear and perjure to have placed the fabric correctly and to have cut with delicacy and precision. What could have happened?

When we cut a pattern in the fabric, there are parts, such as necklines and shoulders, that can be stretched by not following the direction of the straight thread.

To avoid this problem and maintain the original dimensions of the pattern during the construction and testing of the garment, the seams must be stabilized to “freeze” them in their correct length and shape. This does not mean that we have to do it in all the seams of the piece, but only in the areas affected by the bias, such as:

  • V-shaped or curved necklines
  • Armholes and curved seams.
  • Shaped waists.
  • All views in these ways.

Seam stabilization is a technique widely used in flat-knit fabrics, although it is also very useful for working with knitwear, which is always more elusive and difficult.

We are going to look at two different methods to stabilize seams: the first is the stabilizer stitching or staystitching and the second is the moldable fleece tape. Depending on the work and the type of gender you have in your hands, one or the other will be more successful.

Stabilizing stitching

  • It is stitching that is done on a single sheet of fabric at the seam allowance, about 3mm parallel to the seam line.
  • The stitch length is standard (2-2.5) and the thread used is matching, because this seam will remain inside the garment once sewn, it does not take off!
  • Immediately after cutting a piece, the necessary seams must be stabilized. Ironing, basting, or transporting cut pieces from one side to the other can be a cause of distortion and future complications.

Having seen the general characteristics of the stabilizer stitching, we will see a step-by-step example in more detail.

STEP 1 cut the pattern

  • Cut the piece and leave it on the table without moving it excessively and without ironing.

We will use the open pattern, instead of putting it on the back, to be able to use it later as a template.

Cut Pattern

STEP 2 Direction and direction of stabilizer stitching

The goal is to stabilize the fabric, so the direction and direction of the stitching are key. In the following image, we can see how the necklines are made twice, and how they change the direction of the stitching depending on whether they are round or peaked.

Long lines on the bias (such as the sides of a skirt) will never stabilize, but only the length from the hip pocket to the waist.

Steering stabilizer stitching

Continuing with the example, in the pattern we have drawn the seam lines for the stabilizer stitching, located 3mm from the seam line.

Draw stabilizer stitching

STEP 3 Do the stabilizer stitching

  • Place the needle at the proper distance for sewing the stabilizer stitching.
Calculate Seam Allowance
  1. Sew the stitching without pivoting at the corners, to avoid stress on the fabric fibers.
Sewing Stabilizer Stitching

STEP 4 check the dimensions

  1.  Put the pattern on a flat surface.
Pattern-template to stabilize seams
  • Place the piece on top and check the dimensions.

We have used the pattern as a template to verify that our piece maintains its shape.

Pattern-template to stabilize seams
  • The shoulder and armhole on the right fit the insole perfectly.
Pattern-template fits with cut piece
  • On the left side shoulder we have not had the same luck. It has shrunk a bit!
Pattern-insole does not fit cut piece
  • To fix it, alternately cut a few stitches to free up margin.
Cut alternative top stitching to free up margin
  • Stretch a little to fit the template. Bravo!
Stretch fabric to fit insole
Stretch fabric to fit insole
  • Tap with the iron (without dragging) to fix the stabilizer stitches, taking the template below as a reference.
Fix the shape of the piece with touches of iron

We already have a body sheet stabilized! Now you have to stabilize the other, in order to start joining front and back.

The stabilizer stitching is also very useful as a limit when making small cuts so that areas such as necklines or armholes have more margin, yes, without deforming!

Fliseline moldable tape

It is the fastest and cleanest method to stabilize a seam, and once you test the tapes you cannot go without them. Surely, in more than one magazine or tutorial you have seen that they use them.

These tapes have a chain in the middle to stop the distortion of the fabric, they are cut on the bias, which makes them extremely moldable and easy to apply to shaped seams. Its last and most precious virtue is that they are thermo-adhesive so that with a little iron they stay in place. They exist in various widths and with chains of different thickness depending on the needs of your project. Highly recommended!

Blister molding ribbons for fleece

Next we are going to see how to apply this wonderful stabilizing tape to our unstable fabric.

 STEP 1 Cut and place on the template

  • Cut the piece.
  • Place it with the wrong side of the fabric facing us, on top of the template.

The fluffy surface of the ironing board can be very useful for pinning the piece to the template.

STEP 2 Present the tape

  • Place the tape with the shiny side down.

The chain line is the one that rules, so in the most curved areas, if the end of the ribbon curls a little, nothing happens.

Present the fleece tape at the neckline

Tape placed ready to fix.

Fliseline bias tape ready to be attached
  • With the tip of the iron and with light taps, fix the tape from one end to the other of the neckline.
Apply the fleece tape with the tip of the iron

Perfectly stabilized neckline with fleece tape. The finish is highly polished and exactly the same shape as the template-template below.

Flugelhine tape applied to the neckline to stabilize the seam

Spending an extra bit of time preparing the pieces to leave the seam at an ideal starting point can be a bit tedious at first, but the results are worth it. Once you incorporate this technique into your sewing repertoire, it will become a habit! In addition to maintaining the original shape, the necklines and sinuous shapes will be more defined in the final garment. Professional sewing!

You will tell me if you already used any technique to stabilize the seams, and if you try any of these two for the first time, we want to read your experiences!

Until next time,

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