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21 Seam Finishes for Knits & Wovens (+ videos)

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What is a seam? And what’s a seam finish?

A “seam” is formed whenever you join two pieces of fabric together. The raw edges of fabric need to be treated in some way so they don’t fray and come undone. “Seam finishes” are different ways to finish the raw edges, make them more durable, and make the inside of your garments look nice and clean. Common seam finishes include serged (or overlocked) edges, zigzagged edges, french seams, and bias bound seams.

It’s especially important to finish your seams on woven fabrics, as they’re prone to fraying. Knits generally don’t fray.

It’s important to select the most suitable seam finish for the fabric you’re using, where the seam is on the garment, and how you’re planning to use the garment. A wool coat will require you to use different seam finishes than a sheer, silk organza blouse. I’ll cover 21 options today, when to use them, and how to sew them (with videos!).

Contents list:

How to sew a basic seam

A basic or plain seam is the foundation for almost all the seam finishes we’ll discuss in this article (except the French seam, hairline seam, and flat felled seam). And it’s the most common seam type you’ll encounter in garment sewing projects. Here’s how to successfully sew a basic seam:

  1. Place two pieces of fabric with right sides facing each other and pin them together. You should now be looking at the wrong side of the fabric. (The “right side” is the pretty side that you want to show on the outside of your project, and the “wrong side” is the side that will be hidden inside the project).
  2. Determine your seam allowance, which is the distance between the cut edge of the fabric and the line of stitching. If you’re using a pattern with seam allowance built into the pattern pieces, the instructions will tell you what seam allowance to use. The most common seam allowances are ⅝” (1.6 cm), ½” (1.3 cm), ⅜” (1 cm), and ¼” (0.6 cm). Align your pinned fabric pieces so that the cut edge is touching the correct seam allowance marking on your sewing machine. 
  3. Sew a line of stitches by following the seam allowance marking on your machine, making sure you backstitch at the beginning and end of your seam. 
  4. Press the newly sewn pieces of fabric with a steamy iron to set the stitches into place. Don’t open the two pieces up before you do this, we just want to apply steam and heat to the line of stitching you’ve just sewn.

From here on out, you have two options on how to press your seam:

  • You can press it open, which means separating the two seam allowances and pressing them into place with an iron. This is good for thick fabrics because you don’t want to create a lump.
  • Or you can press the seam closed, which means laying the two seam allowances to one side of the stitching and pressing it into place. This is common in garment sewing because then you can finish the seam in one go, not two.

Now that you’ve sewn a basic seam, you’ll need to finish the raw edges. We will now go through 21 of the most popular and useful techniques to finish your seams with photos and step-by-step videos. 

Pinked seams

What is it?

Pinked seams are achieved by trimming the seam allowance using pinking shears, which are scissors with zigzag-shaped blades. By cutting a zigzag pattern into the fabric, the fraying is minimized. 

When to use it?

  • Pinked seams work best on light-medium to heavy weight woven fabrics that don’t fray heavily.
  • Avoid using it for garments that will be worn heavily and washed often, as well as very lightweight fabrics, as the pinking will not completely prevent fraying.

Pros:

  • Very quick and easy to do
  • Creates no bulk
  • The seam is easily accessible for future alterations

Cons:

  • Doesn’t stop all fraying
  • Not suitable for knit fabrics
  • Requires specific equipment (pinking shears)

How to sew it: 

  1. Start by sewing a basic seam. Using pinking shears, trim a small amount (about ⅛” / 0.3cm) from the raw edge. Make sure you don’t trim off too much so that if the fabric frays with wear, there will be a safe distance between the raw edge and seam line. 
  2. Finish by either pressing the seam allowances open, or closed and to the side.

Seam finishes using a sewing machine:

Zig zag 

What is it?

A zigzag seam finish is done by sewing a zigzag stitch along the raw edge.

When to use it?

  • This method is best paired with medium to heavy weight woven fabrics that don’t fray too much. The zigzag stitch can “shred” through very lightweight fabrics, so it’s best to avoid using it on them.
  • It’s not the best option for garments that will be heavily used, since the raw edges aren’t fully enclosed.
  • Although it can be used on seams that are pressed open and closed, sewing through two layers of fabric rather than one provides some extra stability to the zigzag stitch.

Pros:

  • Quick and easy to do.
  • Doesn’t create any bulk.
  • The seam is left easily accessible for future alterations.

Cons:

  • The raw edges are not completely enclosed. A little bit of fraying will happen on the raw edge but it generally won’t go past the zigzag.
  • Doesn’t suit lightweight fabrics.
  • Doesn’t suit heavily-used items.

How to sew it: 

Step 1: Start with a basic seam and sew a line of zigzag stitches about ¼” (0.6cm) away from the first line of straight stitches. Use a medium zigzag stitch and a lower tension to minimise the tunnelling effect that can happen with zigzag stitches. I used a zigzag stitch with a width of 4 and a length of 3, and turned the tension down to 2. Sew a few samples on scrap fabric to determine the best settings for your machine and fabric.

Step 2: Trim the raw edges off very close to the zigzag stitches.

Step 3: Press the seam allowance closed to the side you prefer. 

Alternatively, you can sew the zigzag stitch on the very edge of your seam allowance, so that the right side of the zigzag is off of the fabric, creating a small knot along the cut edge of the fabric, “binding” the raw edge using thread.

Mock overlock 

What is it?

A mock overlock is an elaborate sewing machine stitch sewn along the raw edge of fabric. The stitching looks similar to an “overlocked” or “serged” seam, but unlike a true serged seam the edge of the fabric is not trimmed in the process.

When to use it?

The mock overlock is a good option for medium to heavy weight woven fabrics, as well as knits which we’ll cover later. 

Pros:

  • Doesn’t require a serger / overlocker
  • Easy to do
  • Doesn’t create any bulk in the seams

Cons:

  • It takes a long time for the machine to finish stitching due to the complex stitch pattern
  • The raw edges aren’t fully enclosed. The raw edge may fray a little but it generally won’t go beyond the stitching.

How to sew it: 

Step 1: Start with a basic seam. Choose the mock overlock stitch on your sewing machine, a lower tension (I turned it down to 2), and sew about ⅛” (0.3cm) away from your original stitch line, through both layers. If you wish to press your seam allowances open, you can also stitch the seam allowances separately but elaborate stitches like mock overlocking really benefit from the stability of two layers of fabric. 

Step 2: Trim the seam allowance close to the mock overlocking.

Step 3: Press the seam allowance to the side. 

Alternatively, you can sew the mock overlocking stitch on the very edge of your seam allowance, so that the outside edge of the stitch is off of the fabric.

Stitched and pinked

What is it?

A stitched and pinked seam is almost identical to the pinked seam, but it has an extra line of stitching between the seam line and pinked edge. This extra stitch line adds some protection against the fraying that can happen with pinked seams. 

When to use it?

  • Works well on light-medium to heavy weight fabrics.
  • Avoid using it on fabrics that fray easily, and on garments that will be washed and worn very often.

Pros:

  • Quick and easy to do
  • Gives more protection from fraying than a pinked seam
  • Doesn’t create any bulk in the seams
  • The seam is left easily accessible for future alterations

Cons:

  • Although the fraying is minimized with the additional line of stitching, the raw edges are not completely enclosed.
  • It requires specific equipment (pinking shears)

How to sew it: 

Step 1: Start with a basic seam and press the seam allowances open or closed. Sew a line of straight stitches a little over ⅛” (0.3cm) from the raw edges on both seam allowances. If you chose to press the seam allowance closed, then sew a line of stitching through both layers, a little over ⅛” (0.3cm) from the raw edge.

Step 2: Using pinking shears, trim about ⅛” (0.3cm) from the raw edge(s). Give it a final press with the iron.

Double stitched

What is it?

A double stitched seam is created by sewing two parallel lines of stitching and trimming the excess seam allowance close to the second line.

When to use it?

  • This is a good method for lightweight woven fabrics. You can use it on very fine, sheer fabrics when you want to keep the seams flexible and fluid, without resorting to more elaborate seam finishes that can create rigid seams.
  • It also works well for adding extra stability to stretch fabrics to prevent them from sagging with time.
  • Avoid using it for garments that will be worn and washed often.

Pros:

  • Really simple and quick to sew
  • Adds extra strength to the seam
  • Creates minimal bulk

Cons:

  • Doesn’t completely enclose the raw edges, so while the second line of stitching will minimize the fraying, it won’t completely stop it. 

How to sew it: 

Step 1: Start by sewing a basic seam at your chosen seam allowance.

Step 2: Sew a second line of stitching ¼” (0.6cm) away from the first line of stitching, between the first line and the raw edge.

Step 3: Trim the excess seam allowance, leaving about ⅛” (0.3cm) of fabric from the second line of stitching.

Step 4: Press the seam allowance to one side using an iron.

Turn and stitch 

What is it?

Also called a “clean finish”, a “turn and stitch” seam is achieved by pressing the seam open, tucking the raw edges on either side under, and edge stitching them into place. You can think of it like individually hemming the seam allowances.

When to use it?

  • This method pairs well with medium weight, stable woven fabrics like cotton.
  • Avoid using it for garments that will be worn and washed very often, as you might start seeing some fraying from the raw edge that’s folded under. 

Pros:

  • Easy to do
  • Looks nice and clean on the inside

Cons:

  • The raw edges aren’t completely enclosed which may lead to some fraying.
  • It doesn’t suit thick fabric because it would create some bulk.
  • It takes longer to fold, press, and edgestitch both seam allowances. There are quicker alternatives.

How to sew it: 

Step 1: Start with a basic seam and press it open.

1a: Place a thin card or some folded-up paper between the seam allowance and the rest of your fabric.

1b: Fold the raw edges of your seam allowances under. Keep the folded section between ⅛” (0.3cm) and ¼” (0.6cm).

1c: Press the fold using an iron to secure it in place.

Step 2: Edge stitch the folded edge of the seam allowance. I like to use an edge stitching foot here to make this step easier and neater. Repeat on the other side. Finish by giving it a final press with the iron.

Self-bound 

What is it?

A self-bound seam is formed by using one side of the seam allowance to bind the other, so that all the raw edges are enclosed. 

When to use it?

  • This seam finish is best paired with light to medium weight woven fabrics.
  • It can be a good alternative to French seams, as it results in a very similar look but you don’t have to keep track of the right and wrong sides of the fabric.
  • Try it on sheer fabrics, and open-front, unlined pieces.

Pros:

  • All the raw edges are enclosed creating a clean finish on the inside

Cons:

  • It can cause bulky seams
  • Time and labor intensive
  • The seam isn’t easily accessible for future alterations

How to sew it: 

Step 1: Start with a basic seam sewn with a seam allowance of ⅝” (1.6 cm), and trim one side of the seam allowance down to a quarter of its original width. 

Step 2: a) Press the untrimmed seam allowance up so that its raw edge is touching the raw edge of the trimmed seam allowance. b) Fold the longer seam allowance up so that its folded edge is touching the initial stitch line. Press it into place.

Step 3: Edge stitch the seam allowance down along the final folded edge you created, right next to the original stitch line. I like to use an edge stitching foot for this step to make it easier to guide the fabric.

Step 4: Press the seam allowance to the side. Place some thin cardboard or folded-up paper between the seam allowance and the rest of the fabric so that the seam allowance doesn’t leave an impression on the face of the fabric as you press. 

French seam 

What is it?

A French seam is done by sewing two pieces of fabric wrong sides together, trimming the seam allowance, and then sewing them again right sides together. It results in all the raw edges being enclosed, creating a neat look on the inside as well as the outside.

When to use it?

  • French seams work best on lightweight fabrics due to the four layers of fabric that will be enclosed on the inside.
  • It’s a perfect option for sheer, lightweight fabrics like organza or chiffon.
  • While it can be done on gently curved seams, it works better on straight seams. 

Pros:

  • The raw edges of the fabric are completely enclosed.
  • It looks very neat and clean.

Cons:

  • Time intensive.
  • Requires extra care and attention to not get the right and wrong sides of the fabric mixed up.
  • It’s difficult to do alterations on the seams later.
  • Doesn’t work well on sharp curves and corners.

How to sew it: 

Step 1: Place your fabric pieces with wrong sides facing each other and stitch at your chosen seam allowance. 

Step 2: Trim both sides of the seam allowance to just under ¼” (0.6cm).

Step 3: a) Press the trimmed seam allowance closed to one side of the stitching line. b) Fold the fabric in half along the stitch line so that the right sides of the fabric are now touching. Press it using an iron to set it in place.

Step 4: Sew a line of stitches ⅜” (1cm) away from the folded edge, making sure all the raw edges are tucked away to the right of your new stitching line.

Step 5: Press the new seam to set the stitches into place. Then open up your fabric, and place some thin cardboard or a folded up piece of paper between the seam allowance and the rest of the fabric to avoid leaving an impression on the right side of the fabric. Press your seam allowance to one side.

Hairline seam

What is it?

A hairline seam is essentially a very narrow French seam with a slightly different construction. It completely encloses the raw edges without any visible stitching on the right side of the fabric. 

When to use it?

  • A hairline seam is ideal for sheer, very lightweight, woven fabrics like organza, chiffon, gauze or voile.
  • It’s best paired with seams that aren’t under stress, so rather than using it on a fitted bodice, try using it for sewing paneled skirts or loose dresses.
  • It can also be used for finishing the seams on very small pieces, such as doll clothes. 

Pros:

  • The raw edges are completely enclosed and neat-looking.
  • In a sheer garment, it’s almost invisible from the right side. The seam allowance is very narrow.

Cons:

  • Time intensive.
  • It requires attention to not get the right and wrong sides of the fabric mixed up.
  • It’s difficult to do alterations on the seams later.
  • Doesn’t work as well on sharp curves and corners.

How to sew it: 

Step 1: Place your fabric pieces with wrong sides touching and stitch at your chosen seam allowance. 

Step 2: Sew a second, parallel line of stitching as close as you can to the first. Try moving your needle 1.5 – 2 mm to the side and follow your original seam line with the center of your presser foot for a really close, parallel second line.

Step 3: Trim both layers of seam allowance very closely to the second line of stitching.

Step 4: Fold your fabric in half along the first line of stitching so that the right sides of the fabric are now touching. Press it so that the stitch line is centered along the fold. 

Step 5: Sew a third line of stitching along the folded edge, making sure all the raw edges are tucked inside the new seam. Alternatively, you can also sew a short and narrow zigzag to cover the first two lines of stitching.

Step 6: Press the seam allowance to the side.

Bias bound seams 

What is it?

Bias bound seams are achieved by applying bias binding to the raw edges of the seam allowance so that they’re completely enclosed. It can be applied to both layers of seam allowance together so that they can be pressed closed, or separately to the two sides so that the seam can be pressed open.

When to use it?

  • Suitable for medium to heavy weight woven fabrics that are opaque.
  • This is a perfect seam finish for unlined, open-front garments such as unlined jackets and coats.
  • Use a lightweight fabric for the binding to minimize bulk. 

Pros:

  • Adds a decorative element to the inside of the garment.
  • Completely encloses the raw edges preventing any potential fraying.
  • Leaves the seam easily accessible for future alterations.

Cons:

  • Requires additional material (the bias binding strips).
  • Creates bulk at the seams.
  • Time intensive.
  • Sometimes catching the back of the binding is tricky.

How to sew it: 

Pressed Closed:

Step 1: Start with a basic seam and prepare your bias tape. You can either make your own from fabric or use premade double-fold bias tape. If you only have single-fold bias tape, just press it in half.

Step 2: Slide your seam allowance into the double folded bias tape so that the raw edge of your seam allowance touches the center crease of the bias tape. You can pin it, baste it, or just hold it depending on the stability of the fabric you’re using. Edge stitch through all layers, sewing both sides of the bias tape to the seam allowance.

Step 3: Place some thin cardboard or folded-up paper between the seam allowance and the fabric to prevent the bulk of the seam finish from leaving an impression on the face of the fabric. Press the seam allowance to the side. 

Pressed Open:

Step 1: Start with a basic seam and press the seam allowances open. a) Slide one side of the seam allowance into the double folded bias tape so that the raw edge of your seam allowance touches the center crease of the bias tape. You can pin it, baste it, or just hold it depending on the stability of the fabric. Edge stitch through all the layers. b) Repeat this on the other side of the seam allowance. 

Step 2: Place some thin cardboard or folded-up paper between the seam allowance and the fabric to prevent the bulk of the seam finish from leaving an impression on the face of the fabric. Press the seam allowances open.

Hong Kong finish 

What is it?

A Hong Kong finish is similar to bias bound seams, but it follows a slightly different construction that reduces the amount of bulk and produces a cleaner look that doesn’t have visible stitching on the inside. To achieve this seam finish, bias binding is applied to either side of the seam allowance and the seam is pressed open. 

When to use it?

  • This is a great option for unlined garments where the inside of the garment will be visible, like open-front jackets and coats.
  • It’s best paired with medium to heavy weight woven fabrics, so that the weight of the binding can be supported by the fabric. 

Pros:

  • It adds a decorative element to the inside of the garment.
  • The raw edges are completely enclosed.
  • Since the seam is pressed open, it can be altered in the future.

Cons:

  • It’s a time-consuming and labour-intensive technique.
  • It requires additional material.
  • It creates some bulk in the seams.

How to sew it: 

Step 1: Start with a basic seam that’s pressed open. Pin the bias tape to one side of the seam allowance with the right sides facing each other.

Step 2: Sew along the pinned edge using a ¼” (0.6cm) seam allowance.

Step 3: a) Press the bias tape away from the seam allowance. b) Wrap the bias tape around the seam allowance and press it into place.

Step 4: “Stitch in the ditch” from the right side to secure the binding into place. To do so, carefully sew exactly in the seam that’s between the seam allowance and the bias tape. You can use an edge stitching foot to make this step easier.

Step 5: If you have any excess bias tape underneath the seam allowance, trim it back.

Step 6: Repeat Steps 1-5 on the other side of the seam allowance, and finish by giving your piece a final press. Place some thin cardboard or folded paper between the seam allowances and the fabric to avoid the seam leaving an impression on the right side of the fabric. 

Flat felled 

What is it?

A flat felled seam is a neat and durable seam finish that’s achieved by wrapping one side of the seam allowance around the other and topstitching it into place. It’s commonly found on denim and workwear garments.

When to use it?

  • This is a versatile seam finish that’s suitable for light to heavy weight woven fabrics.
  • It works especially well for garments that will be heavily used and washed.
  • Suits people who have sensory issues as the seam allowance is flat and won’t rub against your body. 

Pros:

  • The raw edges are fully enclosed, which creates a strong seam that looks nice on both sides.
  • The seam allowances are secured to the fabric so that they’re completely flat, creating a comfortable wearing experience.

Cons:

  • Time and labour intensive.
  • The topstitching can be tricky to do on areas like legs or sleeves.
  • It has at least one line of stitching that’s visible on the right side of the fabric.
  • It’s difficult to do alterations on the seams.

How to sew it: 

Step 1: Start with a basic seam sewn with a seam allowance of ⅝” (1.6cm). Trim one side of the seam allowance down to a little under half its original width.

Step 2: Fold the untrimmed seam allowance up so that it wraps around the trimmed seam allowance. The raw edge of the untrimmed seam allowance should now be touching the sewing line. Press it into place.

Step 3: Open up your fabric and press the enclosed seam allowance to one side along the sewing line, so that the raw edge is hidden under.

Step 4: Edge stitch the folded edge of the seam allowance down to secure it into place. I like to use an edge stitching foot to make this step easier and neater.

Tip: With this method, you can pick between two options:

  •  If you sew the two pieces of fabric with the right sides facing on Step 1, you will have a single line of stitching visible on the right side of the garment.
  •  If you sew the two pieces of fabric with the wrong sides facing on Step 1, you will have two lines of stitching visible on the right side of the garment and the inside of the piece will be flatter, which may feel more comfortable to wear.

Mock flat felled 

What is it?

A mock flat felled seam is a variation on the flat felled seam that uses a serger / overlocker to achieve a less bulky end result. There are a few different ways to sew it, which we’ll outline here.

When to use it?

  • This is a good alternative to flat felled seams for instances where you want to reduce the bulk in the seams. Rather than creating 4 layers of fabric at the seams, this method results in 3 layers of fabric.
  • It’s suitable for light to heavy weight woven fabrics, and for garments that will be worn and washed often. 

Pros:

  • It’s relatively quick and easy to sew.
  • The seam allowance is secured to the fabric so it won’t rub against the skin.
  • It creates less bulk than a flat felled seam.

Cons:

  • Requires expensive equipment (serger).
  • Doesn’t look as clean on the inside.

How to sew it: 

Method 1:

Step 1: Start with a basic seam. Serge through both layers of seam allowance. I let the serger trim the seam allowances to about ¼” (0.6cm).

Step 2: Press the serged seam allowances to one side.

Step 3: Topstitch ¼” (0.6cm) away from the initial stitch line, making sure to catch the free edge of the seam allowance with your stitching. 

Optional: If you, like me, love the look of double topstitching, you can make these small tweaks to this method. When trimming your seam allowance with your overlocker, leave them a little under ⅜” (1cm) wide. First edge stitch about ⅛” (0.3cm) away from the original stitching line, then top stitch ¼” (0.6cm) away from the edge stitching. This will give you that classic double-topstitched look you often see on denim garments. 

Method 2:

Step 1: Sew a basic seam with a ⅝” (1.6 cm) seam allowance. Serge one side of the seam allowance, making sure you don’t trim too much fabric off.

Step 2: Trim the other side of the seam allowance to half its original width.

Step 3: Press the seam closed, so that the serged, wider seam allowance is covering the trimmed side.

Step 4: Topstitch the seam into place, making sure the stitching is parallel to the initial seam line. 

Hand-sewn seam finishes:

Blanket stitch

What is it?

As the name suggests, a blanket stitch is often used to finish the edges of blankets using a simple yet decorative hand stitch. It’s very similar to the overcasting / whip stitch, but it has an added step to it. It’s worked by hand, often using embroidery thread. As it binds the raw edge of the fabric it can also be used as a seam finish.

When to use it?

  • The blanket stitch works best on thicker materials like wool coatings or felts.
  • As it doesn’t enclose the raw edges and it won’t completely prevent fraying, it’s best suited for tightly woven or felted fabrics that don’t fray easily. 

Pros:

  • It adds a decorative finish to the inside of the garment.
  • It’s simple to do.
  • Doesn’t require a sewing machine.

Cons:

  • Time intensive.
  • Doesn’t fully enclose the raw edges.

How to sew it: 

Step 1: Start with a basic seam and press it closed. Thread your needle, double up the thread and tie a knot at the ends of the thread.

Step 2: You will always be working the thread from the back to the front. Come up from the back to the front, about a ¼” (0.6cm) from the raw edge. Come back up in the same spot, but before you pull the thread tight, put your needle through the loop that has formed, then gently pull the thread. Come back up, leaving about ¼” (0.6cm) between the stitches, and put your needle through the loop that forms. 

Step 3: Repeat until you reach the end of the seam and tie a knot at the end.

Step 4: Press the seam closed.

Overcasting by hand / Whip stitch

What is it?

Also called a “whip stitch”, the “hand-sewn overcast” stitch involves wrapping thread around the raw edges of the seam allowance to minimize fraying. 

When to use it?

  • Because the raw edges aren’t enclosed, this method doesn’t work too well on loosely woven fabrics that are prone to fraying.
  • It’s better suited to tightly woven fabrics of different weights, and for garments that will not be used heavily or washed often.
  • It can be done on seams that are pressed open or closed.

Pros:

  • Easy to do.
  • Doesn’t require a sewing machine.
  • Doesn’t add bulk to the seams.
  • Looks simple and elegant on the inside.

Cons:

  • It doesn’t prevent all the fraying.
  • Time intensive.

How to sew it: 

Step 1: Start with a basic seam that’s pressed open or closed. Thread your needle, and tie a knot at the end of your thread. You will be working from right to left to do this stitch.

Step 2: Come up from the back to the front, about a ¼” (0.6cm) from the raw edge. Moving about ¼” (0.6cm) to the left, come up from the wrong side again, forming a little loop around the raw edge. Don’t pull the thread too tight to avoid rolling and crimping the edge of the fabric.

Step 3: Repeat Step 2 until you reach the end of the seam. Make another knot at the end of the stitching.

Step 4: Give the seam a final press, pressing it open or closed.

Felling by hand

What is it?

Felling is basically a hand-sewn alternative to flat felled seams. Just like in flat felled seams, one side of the seam allowance is trimmed back, and the longer side is wrapped around the shorter part and secured into place. Whereas flat felling by machine uses topstitching for this last step, felling is done by small hand stitches to achieve a beautiful, invisible look on the face of the garment.

When to use it?

  • This is a really versatile technique that can be used on all weights of woven and knit fabric.
  • It’s particularly useful for historical reconstruction projects.
  • Good for tricky areas on garments like armscyes or sleeves. 

Pros:

  • Looks invisible on the right side when done correctly.
  • The raw edges are fully enclosed so there’s no possibility of fraying and the inside looks really clean.
  • It’s easier to do on tight and tricky areas when compared to machine sewing.

Cons:

  • Time and labour intensive.

How to sew it: 

Step 1: Start with a basic seam. Trim one side of the seam allowance to just under half its original width.

Step 2: a) Fold the untrimmed seam allowance up so that it wraps around the trimmed seam allowance. The raw edge of the untrimmed seam allowance should now be touching the sewing line. Press it into place. b) Open up your fabric and press the enclosed seam allowance to one side along the sewing line, so that the raw edge is hidden under. 

Step 3: (Optional) Hand baste the wrapped and pressed seam allowance. This isn’t necessary on fabrics that press well and on straight seams, but I find it really useful to do on shiftier fabrics and on curved seams like the armscye.

Step 4: a) Using matching color thread and a small, sharp needle, start by anchoring your thread to the bottom of the seam allowance. b) Pick up one or two threads off the fabric, just next to the seam allowance. c) Next, go into the folded edge of your seam allowance right where you picked up the threads from the fabric, and come back up in about ¼” (0.6cm). Repeat steps 4b and 4c until you reach the end of your seam. Don’t put too much tension on your stitches to make the end result as invisible as possible.

Step 5: If you basted your seam allowance into place in step 3, remove the basting stitches.

Alternatively, you can skip the pressing and basting steps, and wrap the seam allowance using your fingers as you go. This will result in a quicker process, but I recommend trying it once you feel comfortable with the stitching method.

Seam finishes using a Serger / Overlocker:

Serged / overlocked seams on wovens 

What is it?

A serged seam is achieved by using a serger / overlocker machine. It trims the edge of the fabric as it sews a thread casing around the freshly trimmed edge. It’s normally sewn using 3 or 4 threads.

The difference between a 3 and 4 thread overlock:

A 4 thread overlock stitch has two “straight” stitches on the left and 2 threads that wrap around the raw edge and encase it. It creates a strong seam. A 3 thread overlock is similar but only has one “straight” stitch on the left. It’s narrower, more fluid, and uses less thread. For finishing raw edges, 3 threads is normally all you need.

When to use it?

  • For light to heavy weight woven fabrics that are prone to fraying. The overlock stitch provides a lot of coverage.
  • And for light to heavy weight knit fabrics, but more on that later.

Pros:

  • Very quick and easy to do.
  • Doesn’t add much bulk to the seams.
  • The seams are left accessible for future alterations.

Cons:

  • Requires an expensive machine.
  • Doesn’t look as clean on the inside.
  • The raw edge may be exposed if the stitching becomes compromised.

How to sew it: 

Pressed Closed:

Step 1: Start with a basic seam. Using your serger, sew and trim along your seam allowance.

Step 2: Press the serged seam allowance to the side.

Pressed Open:

Step 1: Start by serging the edges of your two pieces of fabric. Be careful not to trim your seam allowance to maintain accuracy. You can disengage the blade of your overlocker to make this step easier.

Step 2: Place your fabrics right sides facing each other, and sew a line of straight stitches along your chosen seam allowance.

Step 3: Press the seam allowances open.

Seam finishes for stretchy knit fabrics:

Unlike woven fabrics, knit fabrics don’t fray when cut. This means that finishing your seams on knit fabrics isn’t as crucial for the structural integrity of the garment. That being said, many people like to finish their seams on knit projects because it looks neater and adds structure to the seams. Here are 4 seam finishes that you can use on stretchy knit fabrics:

Serged seam

What is it?

A serged seam is achieved by using a serger / overlocker machine. It trims the edge of the fabric as it sews a thread casing around the freshly trimmed edge. It’s normally sewn using 3 or 4 threads. Unlike with woven fabrics, you can use your serger to create the seam and finish the seam allowance in one go. Overlock stitches also stretch when used on stretchy fabrics.

When to use it?

You can use a serger on all weights and stretch levels of knit fabric, both to finish your seams and for sewing the pieces together. 

Pros:

  • Very quick and easy to do.
  • Doesn’t add much bulk in the seams.
  • Creates stretchy seams.
  • The garment will look professionally made on the inside.

Cons:

  • Requires expensive equipment.

How to sew it: 

Step 1: Using your serger, sew and trim along the raw edge.

Step 2: Press the overlocked seam allowance to the side.

Overcast 

What is it?

This seam finish is done by sewing an overcasting stitch to both join the two pieces of fabric and neaten the seam allowance in one go. It’s made on a sewing machine. It looks like a straight stitch with some diagonal or perpendicular lines growing out of it. Some sewing machines come with multiple overcasting stitches included. In this case, make sure you select one that’s suitable for knit fabrics so they can stretch.

When to use it?

You can use an overcasting stitch to assemble and finish the seams on all weights and stretch percentages of knit fabric.

Pros:

  • You can do it on most regular sewing machines, but basic machines may not have this stitch.
  • It’s easy to do.

Cons:

  • The seam allowances may not look as neat on the inside.
  • The stitch is more complex so it will take a bit longer to sew.

How to sew it: 

Step 1: Using the overcasting stitch on your sewing machine, sew the two pieces of fabric right sides facing together. You may need to turn down the tension to stop the edges from curling under – I turned my tension down to 2.

Step 2: Trim the excess seam allowance close to the edge of the stitching.

Step 3: Press the seam allowance closed to one side.

Mock overlock 

What is it?

A mock overlock is done by sewing an elaborate stitch along the raw edge. The stitching mimics the look of an overlocked / serged seam, but unlike a true serged seam the edge of the fabric is not trimmed in the process. It’s made using a sewing machine.

When to use it?

  • You can use a mock overlock stitch on knits of all weights.
  • This stitch type is stretchy, so you can also use it to sew the two pieces of fabric together.

Pros:

  • It doesn’t require a serger / overlocker machine.
  • It’s easy to do.
  • It doesn’t create any bulk in the seams.
  • The stitching will stretch with the fabric.

Cons:

  • It takes a long time for the machine to do the stitching due to the complex stitch pattern.
  • The raw edges aren’t fully enclosed. 

How to sew it: 

Step 1: Start with a basic seam. Using the mock overlock stitch on your sewing machine, sew about ⅛” (0.3cm) away from your original stitch line, through both layers. If you wish to press your seam allowances open, you can also stitch the seam allowances separately but elaborate stitches like this really benefit from the stability of two layers of fabric. You may need to turn down the tension to stop the edges from curling under – I turned my tension down to 2.

Step 2: Trim the seam allowance close to the mock overlocking.

Step 3: Press the seam allowance to the side. 

Double stitched and trimmed

What is it?

A double stitched seam is created by sewing two parallel lines of stitching and trimming the excess seam allowance close to the second line.

When to use it?

  • In addition to using it on woven fabrics, you can also use this method for knit fabrics of all weights.
  • It adds some extra stability and structure to the seams to prevent them from sagging with time.
  • It will also help with the rolling that can occur with lightweight knit fabrics like jerseys.

Pros:

  • Easy and quick to sew.
  • Adds extra strength and structure to the seam.
  • Creates minimal bulk.

Cons:

  • The raw edges aren’t completely enclosed.
  • It doesn’t look as professional as a serged seam.

How to sew it: 

Step 1: Start by sewing a basic seam at your chosen seam allowance. If the seam needs to stretch with the fabric, use a stitch type that can stretch like a stretch / lightning stitch or a zigzag stitch.

Step 2: Using a straight stitch, sew a second line of stitching ¼” (0.6cm) away from the first line. 

Step 3: Trim the excess seam allowance, leaving about ⅛” (0.3cm) of fabric from the second line of stitching.

Step 4: Press the seam allowance to one side.

What to read next:

This article was written by Nisan Aktürk and edited by Sara Maker.

Nisan Aktürk (author)
Nisan started her sewing journey in December 2019 and already has a fully handmade wardrobe. She’s made 50+ trousers, 20+ buttoned shirts, and a wide array of coats, jackets, t-shirts, and jeans. She’s currently studying for her Sociology Master’s degree and is writing a thesis about sewing. So she spends a lot of her time either sewing or thinking/writing about sewing! Read more…

Sources:

These sources were referenced in July 2022.