Hemming and Seam Finishing
Machine Sewing Class

In order to prevent the raw edges of woven fabric from fraying, they need to be finished where they are exposed on seams or hems. There are many ways to do this, and in this lesson I'm going to show you a few of the most common and most useful. Then we'll use two of them to finish our grocery bag project.

Zigzag Stitching

Some of the seam and hem finishing techniques we're going to talk about use another stitch on your sewing machine: the zigzag stitch, so first let's take a minute to learn how to set up a sewing machine for sewing a good zigzag.

Look at the stitch selector on your machine and figure out how to select a zigzag stitch. On my machine you do this by turning the stitch selector dial to the 'C' section which shows a range of zigzag widths. Turning the dial to different points in this range will adjust how wide your zigzag is. Turning the stitch length selector while you are in zigzag mode will adjust how long your stitches are, which in this case means how spread out the zigzag appears (lower numbers will make the stitches look more like a compacted slinky, larger numbers stretch the slinky... if that makes sense).

To see what I mean, put a piece of fabric in your machine in zigzag mode and try sewing.

Now play around with the dials to see how moving each one changes the look of the stitches. Sewing with the stitches extremely close together is better for finishing raw edges or sewing buttonholes, while sewing with them slightly farther apart is better for creating stretch seams (we'll talk about this more in a few lessons).

Adjust the dials until you get something that looks about like this:

When you are sewing a zigzag, the ideal stitch tension will make the bobbin thread invisible on the top of the fabric, but the top thread will show slightly on the bottom of the fabric like this:

If the bobbin thread is showing on the top of the fabric, or the stitches are puckering the fabric, the top thread tension is probably too tight. Try adjusting it until you get a stitch that looks like the two above.

Hemming With Zigzag

Now let's try using this zigzag in a simple hem.

To try this, take a piece of fabric with a straight edge, and sew a zigzag stitch 1/4" in from the edge of the fabric, backstitching to lock the stitches on both ends.

Now take your fabric scissors and cut away the 1/4" of extra fabric, being sure not to cut through the stitches.

Press the zigzagged edge up onto itself an even 1 1/2". Use your clear ruler or seam gauge to make sure the fold is consistent.

Pin the hem and then sew it with a straight stitch just below the zigzag.

This is a very simple and quick hem that I wouldn't recommend on projects where the inside of the hem is going to be visible, or on fabric that unravels easily, but it can be a good option for heavy duty fabrics and fabrics that don't fray easily.

Folded Hems

We've already made one version of a folded hem on the pocket of our grocery bag, but there are a few variations.

As you've seen, one very basic way to finish the edges of fabric, is to press them over twice onto themselves so the raw edge is hidden, then stitch the folds down. You can vary the width of the folds here for different applications, for example, a 1" or 1 1/4" wide fold might look better than an 1/2" fold as the top hem of the grocery bag, but a 1/4" fold would be better for a light scarf. This method is also how you hem jeans.

Another slightly less bulky variation on this technique is to make the inner fold smaller than the outer fold. To try this, take a piece of fabric with a straight edge, and press the edge up onto itself 2".

Then take the raw edge you folded up and fold it under about 1/2", making the resulting hem 1 1/2" wide.

Press this fold, and pin and sew your hem 1/8" - 1/4" away from the fold.

Hemming With Hem Tape or Twill Tape

Another way to finish a hem is to use hem tape or twill tape to cover the raw edge. With the right kind of tape, this method is slightly less bulky than a folded hem and can be useful when you don't have a lot of material to hem with, for example if you were lengthening a skirt or pants.

To try this technique, take another piece of fabric with a straight edge, and press the edge up 1". Then unfold and pin a piece of twill or hem tape to the edge of the fabric so it is overlapping by about half the width of the tape.

Sew the tape down to the fabric on the overlapping edge.

Then fold the hem up again, pin and sew the top edge of the twill tape down, enclosing the raw edge of the fabric.

Seam Finishing

When you are sewing seams, it's usually a good idea to treat the raw edges of your seam allowances with some kind of seam finishing treatment. When these raw edges are completely hidden, for example, under a lining, seam finishing is mostly done to prevent the fabric from fraying or unraveling. Sometimes, however your seam allowances will be more visible, such as inside an unlined garment, or on the grocery bag we're making, and in these cases, seam finishing is also aesthetic.

I'll show you a few simple ways to finish seams, from extremely simple to slightly more complex.


The most basic way to finish seams is to use pinking shears to create a jagged edge on your seam allowances. Pinking shears are scissors that have a zigzag blade that cuts a shaped edge in fabric. Cutting the edge this way makes the yarns of the fabric less likely to fray. You should really only use this technique when the edges you are pinking are going to be completely hidden and inaccessible once your piece is finished.

You usually pink a seam after your sew it, so if your seam needs to be pressed open, press it, then pink the edge of each seam allowance separately.

Or, if you don't need to press your seams open, just use your pinking shears on both layers of seam allowance together.

Seam Finishing With Zigzag

Another way to finish the inside of seams is to use your zigzag stitch similarly to how we used it on our hem.

There are two ways to do this. One is to use the zig zag to finish each seam allowance separately. To do this, sew your seam and press it open, then sew a zigzag about 1/4" in from the edge of the fabric on each seam allowance separately. Make sure you are folding the rest of the fabric out of the way so you are only sewing through the seam allowance.

Then use your scissors to trim away the extra 1/4" being careful not to cut into the zigzag. This method is good for seams that need to be pressed open.

For the second method, sew your seam, but don't press it open. Then sew a zigzag on the seam allowance right outside the sewing line, sewing the two layers of the seam allowance together.

Trim away the rest of the seam allowance. Now if you need to, you can press open the seam, by pressing the zigzagged seam allowance to one side. Seams finished like this won't usually lay quite as flat as seams finished the first way, so they are good for different purposes.


Using double fold bias tape can be a great way to enclose the raw edge of fabric and add a touch of color to a project. Just as we did with the zigzag finishing, you can use this technique on either each seam allowance separately, or on both of them together.

To finish each seam allowances separately, sew a seam, then press your seam open. There are a few different ways to sew on the bias tape, but I'm going to show you the easiest for now. Take a piece of double fold bias tape and sandwich the edge of one seam allowance between two folded layers, pushing it all the way onto the fabric and keeping it even.

Pin it down, then sew all the layers together close to the inner edge of the bias tape. Repeat on the other side of the seam allowance. (When you are doing this on a real project you would usually want to use matching thread to blend in with the tape, but I'm using contrast thread here so you can see where I'm sewing).

To finish both seam allowances together, sew a seam, but don't press it open. Trim the seam allowance down to about half and inch, then sandwich both layers of the seam allowance inside the bias tape.

Pin and sew. Then press the seam open, folding the bound seam allowances to one side.

We are going to use this technique to finish the seams of our grocery bag, and it can also be a good technique for creating decorative seams on the outside of something.


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            "title": "greening",
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    "question": "True or False: You need to finish the edges of woven fabric so it doesn't fray.",
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            "title": "True",
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    "correctNotice": "Well Done!",
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Project: Finish the Grocery Bag

Now we'll use some of the hemming and seam finishing techniques we just learned to finish the grocery bag we started in the last lesson. There's just one more thing I'd like to mention before we start sewing again.

Order of Operations:

One of the most important parts of making any project is figuring out the best order in which to put it together. Sewing is often a logical puzzle: which do I do first, finish the seams or sew them together? If I sew the bag together before I add the straps, will I still be able to attach them?

I am presenting techniques here in a certain order, but when you start your own sewing projects, you will see that this order of operations usually needs to be re-arranged depending on the structure of what you're sewing. For example I could have had you hem the grocery bag before you attached the straps or sewed the side seams, like I did with this other version of the bag:

There is almost always more than one right way to construct something, so don't get too hung up on doing it the "right way," just do what works.

That being said, figuring out an efficient order of operations is one of the most important parts of planning any project, and if you don't think it through fully, you will sometimes find yourself in a jam later! I spend a lot of time thinking about how everything will go together every time I make something. Keep in mind that time spent planning this way is not time wasted, it is time saved... believe me I don't always remember this, but you should :)

Pin the Binding to the Side Seams

Ok, first, we're going to bind the side seams with bias tape for a decorative seam finish. To do this, take your double fold bias tape, and cut two pieces that are 1/2" shorter than the length of your side seams.

On the bottom corners of the bag, we are going to create a clean finish on the binding. To do this, open up the end of the bias tape and fold half an inch down into itself. Now take the bottom corner of your bag and slip the bias tape over the end of the seam allowance, so the tape encloses the raw edges of the fabric like this:

Pin the rest of the tape on, it should stop about 1" below the top of the bag.

Repeat on the other side seam.

Sew on the Binding

Now sew the binding on, stitching about 1/8" in from the inner edge. It will be easier to sew if you start at the unfolded top end of the binding not the folded bottom end. Remove the pins as you sew, and lock your stitches at both ends.

Repeat on the other side seam.

Take your bag over to your ironing board, flip it rightside out, and put it over the end of the ironing board. Spread one side seam flat, pushing the bound seam allowance to one side, and press the seam flat. Don't worry about pressing all the way down to the bottom corner.

Repeat on the other side, pressing the seam allowance in the same direction.

Hem the Bag

Now we're going to finish the top edge of the bag with a folded hem. You could also use another hem treatment that we learned if you wanted.

Draw a line 2" down and fold and press once to meet the line all the way around.

Then fold again and press down the double fold.

Pin in a few places to secure your hem if you want, then take it to your sewing machine. Before you start sewing, remove the extension table from the machine to expose the free arm, this will let you easily sew around the loop of the hem without accidentally catching the other side in your stitches.

Start sewing at one of the side seams, and stitch the hem down all the way around about 1/4" from the inner fold, using your seam guides as a reference. As always, lock your stitches at both ends.

When you get to the seam areas where you are sewing through a few layers of fabric, your sewing machine might give you a little trouble. Go slow, push the fabric through a little with your hands and use the handwheel to help you along if you need to.

Sew the Box Corners

The last step in making the bag is to give it some dimensionality by sewing the corners to create a boxed bottom.

To do this, fold your bag with the side seams matched like this:

Play around with the corners until they are creating two 90 degree angle points that match up at the bottom, then flip one of the corners up so it looks like this:

Take your ruler and draw a 5 1/2" line that evenly cuts off the corner parallel to the sewing line of the strap. Place a couple of pins along this line. Repeat on the other corner, then sew along these lines.

Now turn your bag rightside out again, fold the corner flaps down and push the corners out so the bottom of the bag forms a box shape.

You're done!!

You're Done!

You made a handy little bag good for carrying all kinds of things! And as you can see, it would be really easy alter this design to make different versions of the bag. I made a slightly different one by silk screening the Instructables logo onto the pocket pieces and using yellow bias to bind the edges instead of hemming them. I also made this version a little larger.

A big part of creating your own projects is just making small alterations to pre-existing patterns and choosing materials that speak to you, so when you're first starting out there's no need to try re-inventing the wheel every time you want to make something.

In the next lesson we'll break out of the straight seam box and learn how to sew curved seams. Then we'll use these techniques to create another easily customizable design: a simple stuffed creature.


Share a photo of your finished project with the class!

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