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Understanding Understitching

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If you are new to sewing, some of the terminology can be confusing. Doesn't "bolt" mean to run away? Cutting something on the "bias" just sounds mean. And, "feed dogs" seems more like a command than a sewing machine part. Trying to understand the various terms, exactly what they mean, how they work, and especially when to use them may seem daunting. But, as you learn each one, they'll become commonplace, and soon "nap" will mean more than dropping off for a little snooze. Today, we meet: understitching, which is not a seam done in a sneaky or under-handed manner and/or by Underdog. Read on to find out what it really is.

By definition, understitching is a line of straight stitching sewn just beyond the seam line between two pieces that have been sewn together to create a seam along an edge. One of the pieces is the outside of your project, the other is the inside. In order to keep the edge sharp and clean, you understitch the inside piece to the seam allowance so it won't roll to the outside along the edge seam and look messy and unprofessional.

Understitching is referred to a lot in garment construction, especially around necklines with facings. For example, when a facing is sewn to the edge of a scooped neckline, you don't want to see the facing rolling out around the neckline when you wear the garment. You understitch the facing to the seam allowance so the facing stays in place. You might also see understitching around the waist of a lined skirt – the style without a waistband.

Although possibly more common in garments, we've found plenty of uses for understitching in home décor sewing. On our Pleated Crib Skirt knife sharp.

Next time you're out shopping for ready made items (a rare excursion for you since finding Sew4home, right?!), look at the inside to see how things are made. You'll notice how often understitching is used to create a professional finish.

How to Understitch

  1. As with the majority of our technique tutorials, we've used unusual fabric and thread combinations so you can clearly see how to execute this technique successfully. In this sample, we selected a light fabric for the inside and a dark fabric for the outside with a bright thread. In your projects, you would use the fabric of your choice (which may or may not be the same for the inside and outside pieces) and thread to coordinate with your selected fabric(s).
  2. If you're sewing a project with instructions provided, such as an off-the-rack pattern or following a downloaded tutorial, there are likely to be references to understitching where appropriate. If you're creating an original, you'll begin to quickly spot where you need to understitch because you'll get that "inside-rolling-to-the-outside" thing happening along a seamed edge. In our example, we will refer to the "inside" as a lining and the "outside" as the right side.
  3. Set up your sewing machine for regular sewing with a straight stitch.
  4. With right sides together and the appropriate seam allowance, sew the right side piece to the lining piece. Remember, the dark fabric is our outside fabric and the light fabric is our lining.
  5. Grade (or trim) the seam allowance to eliminate excess bulk in the seam. This means you trim one seam allowance edge narrower than the other.
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  6. Press the graded seam allowance toward the lining.
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  7. Lay the sewn piece out flat, right side up. The lining piece should be to the right and the right side piece to the left. The seam allowance should also be laying to the right underneath the lining... since you just pressed it that way.
  8. Place this flat piece under the machine's presser foot. The seam line should be just to the left of the needle, approximately ⅛". You are preparing to stitch on the lining side.
    NOTE: We're using an open toe foot so you can see exactly where to stitch. You would use a standard presser foot on your machine.
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  9. Sew a straight line of stitching through the lining and the seam allowance underneath. This line of stitching should be as long as the edge seam you want to keep from rolling.
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  10. Fold the two pieces back together along seam line (ie. wrong sides together) and press for a sharp edge. Here it is from the back.
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  11. From the front, your seam edge should look straight and clean, just like the photo below. Can't see the lining, can you?
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  12. In case you're wondering what our sewn piece would look like without the necessary understitching... here's a second sample we made. It is identical is all ways except for the understitching.
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Sample Creation and Instructional Outline: Jodi Kelly


Comments (23)

Nick Smolinske said:
Nick Smolinske's picture

It took quite a bit of reading, but I think I get it.  Step 7 confused me for a while, because I thought it was referring to the picture above it, but it seems like it refers to the picture below?  You might want to edit the article to make that more clear.

Liz Johnson.Editor.Sew4Home said:
Liz Johnson.Editor.Sew4Home's picture

@ Nick Smolinske - glad you figured it out. The standard throughout the site is for the picture to go below the copy it is referring to.

sarahjadesigns said:
sarahjadesigns's picture

I've been sewing for years, but I'm a newbie when it comes to making clothing. This tutorial helped me tons to decipher my pattern instructions, thanks!

Sunnie Mitchell said:
Sunnie Mitchell's picture

I've been sewing for fifty+ years, knew about understitching but even with excellent reference books never quite got the hang of it until this tutorial. Thank-you!

jadasgma said:
jadasgma's picture

I've been sewing for 40 + yrs, and I'm almost embarrassed to admit that I had not heard of under stitching until today. I almost bypassed this step because the pattern directions made it seem too complicated. I'm glad my google search directed me to your site. Your instructions and visual example was so easy to follow and the under stitching really made a difference on the dress I'm sewing!  Now I'm wondering how did I do without it for all these years. 

Ani said:
Ani's picture

I keeo looking into inline example and about three different books and couldnt wrap my head around int!! Thank you so easy no i saw you very clear example x x x

PaisleyGirl27 said:
PaisleyGirl27's picture

OMG this is the most simplist, easiest instructions I have every come across.  Absolutely Brilliant.  Extremely helpful.

Anonymous said:
Anonymous's picture

Excellent tutorial but photo 12 is a bit misleading.  Without the understitching there is not reason why all that lining would be showing if the seam was pressed open and then the work folded and pressed with the sewing at the edge.  That has been set up like that for the photo and it is obvious that the fold has been ironed in at the edge of the trimmed seam allowances, not on the stitching line at all.

The difference that the understitching makes is to actually pull the main fabric over the edge so there is no chance of tiny bits of lining showing.

firegirl said:
firegirl's picture
thanks so much for alwawys showign me new stuff to improve my projects or understand what the mean on some of the instructions smilies/smiley.gif
Ann W. said:
Ann W.'s picture
A simple explanation and great photos for a technique that solves the fabric rolling issue. Thanks for the tutorial, which I accessed through Quality Sewing Tutorials.
tdjohnson67 said:
tdjohnson67's picture
I can remember my grandmother teaching me this important but simple technique. It has come in handy many many times.
Margie S. said:
Margie S.'s picture
Thank you for a very good tutorial. Seeing actual photographs (and videos) makes learning so much easier, quicker and effective. I love the fact you make these available as PDFs I can use for future reference. Thank you!
Liz Johnson.Editor.Sew4Home said:
Liz Johnson.Editor.Sew4Home's picture
@ Kiffyn andreasen - we will be posting about the latest contest winners, including Hello Kitty, on Monday.
Liz Johnson.Editor.Sew4Home said:
Liz Johnson.Editor.Sew4Home's picture
@ Kathy B and @ patsinclair uk -- smilies/grin.gif -- ahhh ... one little "a" makes a lot of difference. Nope, our lining was in no way derogatory. I fixed it... even though I kind of liked it the way it was.
Kathy B said:
Kathy B's picture
Me too - what did the poor lining do that was so insulting??smilies/cheesy.gif
Rashida said:
Rashida's picture
This makes so much sense! It has confused me for so long. It's amazing that just stitching the lining and seam allowance together stops the rolling smilies/smiley.gif
patsinclair uk said:
patsinclair uk's picture
Was the lining of your reusable shopping tote bag really insulting, or was it insulated!!! Sorry, couldn't resist.
May I take this opportunity to say that I love your site and read the tips every day.
No offence intended, just my sense of humour!smilies/cheesy.gif
Kiffyn andreasen said:
Kiffyn andreasen's picture
did you give away the hello kitty sewing machine?
michelemilam said:
michelemilam's picture
OMG! I get it! I's so simple, yet it has eluded me for years.

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