Essential Techniques: Discover the Secret to Perfectly Sewn Necklines!

Collarless necklines come in many forms. Some come up close to the neck, like a jewel or round neckline, while others are more revealing, like a V-neck or bateau-style neckline. But no matter the shape, these garment necklines all share one thing in common: In order for them to look just right, the facings that finish them must turn ever so slightly below the neckline edge.

What’s the secret to making your neckline turn just so? Understitching.

Understitched Boat Neck Dress

As a sewing instructor, I amazed at how many of my students have never heard of understitching. They don’t know what it is, how to execute the technique or the role it plays in achieving a beautifully smooth and well turned neckline. But this technique is one of those essential sewing techniques every sewer should know!

Understitching on a red dress on Bluprint!

What is understitching?

Understitching is that line of stitching that appears on the facing less than 1/16” from the neckline seam on the underside of the garment. It connects the facing to the neckline seam allowances. This simple sewing technique makes the neckline turn just enough so the connected facing lies totally flat and below the neckline edge.

In theory the technique is very simple, but the actual process of understitching requires a keen eye, some good pressing and a very careful finesse of the hands to ensure the seam allowances remain properly positioned under the facing while stitching. Whether using a proper facing or a bias strip facing, understitching is the secret to a well-turned, smooth neckline edge.

Here is how to understitch a facing:

1. Attach the facing or bias strip facing as the pattern instructs.

Attach the facing or bias strip facing & trim seam allowance
2. Trim the seam allowance down to ⅜” and clip around the curves.

Press the facing away from the garment as much as possible
3. From the right side of the garment, press the facing away from the garment as much as possible. Next, turn the garment over and press the seam allowances towards the facing.

Note: The seam allowances MUST be directed towards the facing/bias strip for the understitching to be truly effective.

Sewing garment on a machine
4. Now, complete the understitching that will secure the facing to the seam allowances. To do so, stitch your thread into the facing less than 1/16” from the neckline seam. Carefully using your hands, make certain the seam allowances remain under the facing and directed away from the garment as you sew, especially when stitching around the curves.

Press the facing down to the underside of the garment.
5. Press the facing down to the underside of the garment. The understitching will help the neckline turn so the facing stays totally concealed under the neckline edge.

Understitched garment neckline

There you have it! Another sewing technique down!

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Don’t stop there! Join over 5000 other students and learn all the fundamental sewing skills you need for expertly tailored garments and boutique-worthy pieces with the Bluprint class 40 Sewing Techniques Every Sewer Should Know!


What’s one essential sewing technique that you find is commonly overlooked?

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