Garment Construction

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 Craftsy!

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!

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 Craftsy class 40 Sewing Techniques Every Sewer Should Know!

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



I couldn’t help but notice that the seam allowance is clipped in the picture but you don’t mention the clipping which is very important…usually clipped in a V shape to allow the extra fabric caused by the curve to not bunch up!


Clipping is mentioned in step 2.

Hannatu kisisi zephaniah

What are the characteristic of a well finished necklines?

Linda Reynolds

Where the neckline is smooth and even all around. The facing doesn’t creep up or at any point is exposed. The understitching, which is the point of this post, is what makes that happen. It helps the facing turn under just right and lies flat against the neckline. Understitching is an important technique to know and has application for when applying all kinds of facings, whether at the neck, sleeve or center front.


Thankfully I finally understand under stitching#


Thanks for explaining under stitching! Are there any tips on how to sew the facing down? Lots of patterns have this as a step, sewing down facing all along its bottom rather than just tacking it at the corners, and I’ve yet to find a way to ease the extra material (either the actual garment or the facing is always longer) without completely tearing my hair out and giving up! I’m currently trying to do this on a Salme Kimono top neckline, and a tortuous bottom hem facing on a Style Arc Ethel top.

Gerri Storey

I have a simplicity pattern which is far from simple. The instructions for applying the facing to the neck is very confusing. Can you help? Thanks.


Hi Gerri.. Same here. I’m attempting to sew Project Runway simplicity pattern 8125 and the neck facings (inner & outer) are a nightmare. Have you sorted yours out?

Tsu Dho Nimh

“I’ve yet to find a way to ease the extra material ”

Snipping “V”s out of the seam allowance before you stitch will take care of the excess material. The sharper the curve, the more V notches you need in that area.

mary e holland

I am having trouble having my V neck facing layflat when turned at the V point


Hey Linda, Thanks for this great explanation. I am new in the sewing world and I am making so many mistakes but I am trying. I know I will be perfect like you. It will be difficult for me to sew Understitching. But I will try your technique to sew my new Salwar neck designs suit.

Anne Runting

This was a great help, my pattern instructions weren’t clear and the dress I’m making for my daughter needed to look professional due to the plunging neckline. I followed your instructions to the letter and am so pleased with the finish, I can’t stop looking at it !! very impressed. Thanks so much


You did not say why the facing was clipped. I am a new seamstress and would like know


I learned this back in the 60s in school (home economics) and from my mom. Dont hear about it much except it is instructed on most dress and blouse patterns. I keep forgetting about clipping the curves with a V instead of just a clip. Does create a smoother look. And yes, I am “old”….in home ec we learned about cooking, shopping, cleaning, sewing, correctly making a bed and setting a table and even some modeling!


I think it’s a shame that “Home Ec” is more of an elective now…should be required.


Leave a Reply

Your email address will not be published. Required fields are marked *

Leave a Reply