How Is Mattress Stitch Done

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How to Join Knitted Pieces with the Mattress Stitch

Mattress stitch makes a practically invisible and nicely flexible seam for joining pieces side to side. You can’t use mattress stitch successfully, however, on pieces that don’t have the same number of rows or a difference of only 1 or 2 rows.

1 Lay out your pieces next to each other, right sides facing up, bottom edges toward you.

You seam from the bottom edge up. If you’ve left a tail of yarn at the cast-on edge, you can use it to get started.

2 Locate the running thread between the first and second stitches on the bottom row of one piece.

Gently pull apart the first 2 edge stitches to see the series of little horizontal — running — threads connecting them.

3 Thread the tail of yarn or a fresh piece on a tapestry needle.

Make sure your tapestry needle is blunt to avoid piercing the yarn.

4 Join the bottom edges of the pieces, using a figure eight.

Work through the two threads on the cast-on row.

5 Bring your needle under the thread; then pick up the running thread between the first and second stitches on the opposing piece.

This step begins your mattress stitch pattern.

6 Work back and forth from running thread to running thread to running thread, keeping the tension easy but firm.

Check the tension by pulling laterally on the seam from time to time. The amount of give should be the same as between 2 stitches.

How to mattress stitch your knits

Published on 28 March 2019 2 min read

So you’ve decided to knit a snuggly jumper, and you’ve done an amazing job so far. Except your jumper is still in several pieces, and now you need to sew it up! Don’t worry – we’ve all been there, and once you’ve mastered how to mattress stitch, you’ll be good to go.

Follow our super easy step-by-step guide to mattress stitch knitting and you can finish up projects with invisible stitch lines and a perfect professional finish!

What is a mattress stitch?

A mattress stitch is a vertical invisible seam that joins two knit pieces together side by side. The seam itself is flexible, neat and firm, making it perfect for finishing up several projects – from jumpers and cushions, to that vibrant patchwork blanket you’ve always wanted to finish.

When should I use a mattress stitch?

A mattress stitch only works when the two pieces have an identical number of stitched rows. It’s perfect for patterns that use the stockinette stitch or ribbing. You’ll want to use it whenever you’re looking for a flat join. Because the stitch is externally invisible, it can even come in handy to make any necessary size adjustments.

How to mattress stitch step-by-step

Lay down the knitting.Place the two pieces to be joined side-by-side, with the right side facing you.

Cut your yarn.As we want this stitch to be invisible, use the same yarn you’ve knitted with (though we’ve used contrasting yarn to show you how to do it). Measure out a piece about three times the length of the seam you want to join, and thread it through a blunt darning needle.

Thread your yarn through the first stitch.Beginning with the left side of the knitting, take your darning needle and insert it into the bottom right hand corner of the first stitch.

Insert your needleupwards from back to front.

Repeat on the right side.Find the first stitch on the bottom left, and insert your needle from back to front.

Thread back through your first hole.Go back into the same hole as you originally inserted your needle through from back to front, and pull the yarn through. Great work: you’re ready to start your mattress stitch!

Thread beneath the two bars.If you pull your knitting slightly apart you will see two horizontal bars. Take your darning needle and thread it beneath the two bars, pulling it through from front to back.

Continue in the same pattern.Match the rows from each side as you zig zag from edge to edge for about 2 inches.

Pull the thread up.Hold the base of the seam until the seam is joined and the stitches become invisible. Try not to pull it too tightly as you don’t want to distort your work.

Continue to the top.Secure the ends by sewing them in. You should be left with a perfectly flush finish, and invisible seam line.

Mattress Stitch – How To Seam Knitting

Mattress stitch is a great seaming technique to use for sewing seams in knitting.

One of the most important things to learn with knitting is how to sew knit seams.

After all, you’ve spent hours, days, weeks and maybe even months knitting up something wonderful and it can be ruined so easily if it isn’t sewn up properly.

And the mattress stitch is very easy to learn. It’s best known for sewing vertical seams like the sides of a sweater. But you can use it wherever you think it will work.

Seaming Knitting Tips

  • If you know ahead of time that you will be sewing your knitting you can leave a long enough tail so that you can use that. It will save you from weaving in another yarn end
  • Try using the same yarn you knit your pieces with. If it’s really thick you might want to either find a yarn a bit thinner that comes close to the same color you used. Or you may want to try some embroidery thread. Embroidery thread comes in many different colors so you’re sure to find one that matches.
  • Use a length of yarn no more than about 16 inches long. It does get worn from the sewing after awhile.

I have lots of pictures to help you. After all it may only take that one extra picture for you to completely understand how to work the mattress stitch.

As always I’m using a contrasting yarn so that you can see what I’m doing.

Mattress Stitch Instructions

If you take a look at your knitting, these are the edge stitches, sometimes called the selvedge edge. Lots of times it is kind of messy but no worries, it will all be sewn up and no one will see it.

Lay your two knitted pieces out with the right side facing you just like the photo.

What you want to do is gently separate the edge stitches from the knitting stitches beside it. See in the photo. Those bars are what you will be using to mattress stitch your pieces together.

Thread your yarn needle and push it through the very last stitch on one piece of fabric (above left photo) If you’d like to keep it in place push it through the same loop again (right photo) to kind of tie it so it won’t move around. (I don’t usually do this but you may like too).

Next, move over to the other knitted piece and push the yarn needle through the very last stitch just like the first. You don’t need to tighten the pieces yet, just keep it pretty loose like in my photo. You’ll see why in a bit.

Sometimes you may find that when you start to sew your knitted piece you have one lonely bar at the beginning of your seaming. If you do see one bar you can put your yarn needle through that one bar.

Just keep in mind that whatever you do on one side of your knitting needs to be done the same on the other side to keep them even.

So move over to the other side and push your yarn needle through that one bar as well (above left photo). Bring the yarn through.

This will keep it even with the other side

Some knitters like to go through one bar all the way up their knitting and others go through 2 bars. It’s just a matter of preference. I like going through 2 bars so from now on I will be going through 2.

Now move over to the other piece of fabric. Always go back to the same place you came out of previously.

Push your yarn needle through those next 2 bars. And bring the yarn through.

Move over to your other piece and go into the same place you came out of before (above left photo), pushing your needle through those next 2 bars and pull yarn through (right photo).

Keep on mattress stitching back and forth for about an inch and then stop a minute.

Here’s the magic moment.

Take your yarn and firmly pull on it to bring your knitted pieces together. Try not to pull too tightly but if you do just stretch it back into shape. Isn’t that cool? You can’t even really see the red yarn. I just love the mattress stitch.

Now just continue seaming up your knitting going from one side to the other side. Every inch to inch and a half pull on your yarn to bring the pieces together.

Keep on seaming all the way up to the top. Pull on the yarn to bring the pieces together.

Here’s what I do at the top. I put my yarn needle through the loop on the other piece like in the photo. Tighten it up a bit.

Then just bring the needle through the loop to kind of knot it and pull. Now you can weave that end in as well.

There ta-da. Looks really good doesn’t it? You can’t even see the red yarn. Oh I know that my poor swatch is stretched but even still it looks pretty cool.

When you actually work the mattress stitch on your knitting it will look excellent and you won’t even see the seam.

And this is what it looks like on the wrong side. I know it is quite a big looking seam right? It’s OK you won’t notice it and it’s not noticeable or uncomfortable at all. Best thing is, it hides the ugly edge stitches.

For those of you who prefer watching I found a great mattress stitch knitting video.

How is mattress stitch done

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Putting it all together

Seam (v) : to join by sewing

You may be aware by now that I have a fondness for circular needles and patterns that don’t require any sewing up. I’ve said repeatedly that seaming is not one of my strong points and I’ve avoided learning how to do it properly like the plague. The term "mattress stitch" has struck fear into my heart any number of times.

Nevertheless I am well aware that there are truckloads of marvelous patterns out there that are knit flat and that seaming is the key to giving them a well-made, professional finish. After all, there’s waaaay too many hours involved in the knitting to have the finished object wind up a disappointment simply because the seams look sloppy. So I’ve bitten the bullet and learned how to do some seaming. And guess what I’ve found out: it wasn’t as hard as I feared.

First some stuff about seaming in general:

In general, you’ll want to use the same yarn for seaming that you’ve used for knitting. [I’ve used a different color yarn for this tutorial so you can more clearly see what’s happening.] If the yarn is unsuitable for sewing up, like a novelty or very loosely plied yarn, or if it’s a bulky weight yarn that will make a thicker seam than you’d like, you might try using embroidery yarn. Since there’s such a wide range of colors to chose from in embroidery yarns, you’ll have a good chance of finding a color to match your knitting. Be sure whatever you’re sewing up with can be washed in the same manner as your knitting yarn and test it before starting for colorfastness.

Block the knitted pieces before starting.

Let me repeat:Block first.

One more time:Block before you start seaming.Your seaming experience and the finished results will be so much nicer.

Baste or pin the garment together in order to try it on before you start seaming. [Note: a basting stitch is loose, temporary running stitch you’ll remove before you start the actual seaming.] It’ll be easier to correct any sizing errors that you may find now rather than after you’ve gone to all the trouble of sewing up. By basting, you’ll also be able to find out beforehand if the two pieces you’re sewing together match up perfectly. If they don’t, it is possible to fudge a little bit by an extra row or stitch every few inches on the longer side. For a difference of more than an inch you’ll be better off doing some ripping out and reworking. Sorry.

Find a comfortable, well-lit spot with a flat working surface. Have a yarn needle ready and the yarn you’re going to use to sew. By the way: use a piece of yarn no more than 18 inches long since it will start to weaken from the friction created by sewing.

If the tail from your cast-on row is long enough [and you may want to leave a longish tail just for this purpose] use it to begin the seam. Thread the tail on a yarn needle and insert the needle into the lowest corner stitch on the opposite piece from back to front :

Then insert the needle from back to front in the lowest corner stitch on the piece that had the yarn attached.

Pull tightly to close the gap then continue seaming using one of the methods described below. If the cast-on tail is long enough to work with, leave it on the yarn needle and use it to seam at least the first couple of inches. If not, use another length of yarn to start your seaming, being sure to leave a tail of at least a few inches that can be securely woven in on the wrong side.

There are many types of seaming to choose from, but I’m going to focus on two here: invisible vertical seaming on stockinette stitch and garter stitch.

Invisible vertical seaming on stockinette stitch (a.k.a. mattress stitch)

This technique joins two pieces of stockinette stitch in such a way that the knitting appears to be continuous. Mattress stitching is done in the space between the edge [selvage] stitch and the stitch next to it, so it has the added advantage of hiding that often misshapen stitch that appears at the end of every row of stockinette stitch. This also means that the seam winds up being as bulky as two stitches, since those two edge stitches wind up hiding on the back side.

Begin by laying the blocked pieces out side by side with the right side facing you.

Pull the edge stitch slightly away from the stitch next to it. You will see a horizontal bar running between the edge stitch and its neighbor. Insert your yarn needle under that bar.

Pull the yarn through the bar (it doesn’t have to be pulled tightly just yet) and then insert the needle under the parallel horizontal bar on the opposite piece. Work back and forth, inserting the needle under the bar on one piece then the other piece until you’ve worked a few rows.

Gently but firmly pull the yarn in the direction of the seam (rather than out towards you) and the two rows of second stitches will start to cozy up to one another.

Stop pulling on the yarn before the seam starts to pucker. Adjust as necessary so that the seam lays flat and neat.

Continue until you reach the top of the pieces. Finish off by connecting the top two corner stitches like you did at the lower edge and weave the remaining yarn in securely on the wrong side.

Invisible vertical seaming on garter stitch

Okay, okay, I have a confession to make. I’ve known how to do this kind of seaming almost as long as I’ve been knitting. And I’ve felt just as strongly about it as I felt about mattress stitch but in the opposite direction. I find seaming on garter stitch positively fun. This is one of those things I’ve realized it’s not too smart to go around declaiming to non-knitters.

Before you start, you’ll need to inspect the edge stitch that’s created when working in garter stitch. Each garter stitch ridge leaves a edge stitch with a top loop and a bottom loop. Garter stitch seaming joins these loops to create the appearance that the knitting is continuous.

Lay the blocked pieces out flat with the right sides facing you. Begin the seam as explained above. Then insert the yarn needle first into the top loop of one piece then into the corresponding bottom loop of the opposite piece.

Work back and forth, consistently using the top loop on one piece and the bottom loop of the other piece for a few inches.

Pull the yarn end, gently yet firmly in the direction of the seam, and the two pieces will come together. Adjust as necessary so the seam lays flat.

This is only a tiny sampling of the techniques that can be used to sew two pieces of knitting together. There are special techniques for sewing in sleeves, seaming techniques utilizing crochet hooks as well as techniques such as backstitching and overcasting.

I’ve used the following two books as guides to overcome my mattress stitch phobia and can’t recommend them enough:

Coming up next issue:

Grafting : Joining two sets of "live" stitches without a seam.

If you have a suggestion for techniques to be featured in a future Knitty, please email Theresa. Be sure the technique is something that you think would be of interest to the majority of Knitty’s readers! If you need individual help or have questions about a specific knitting technique, try Knitty’s message board or a forum like Knitter’s Review.

You can follow along on Theresa’s own knitting adventures at her weblog, Bagatell :: Knitting in Norway.

Mattress Stitch Seam

This is the most common technique used to sew vertical seams. When done correctly it is virtually invisible from the right side; it is therefore sometimes called a blind stitch seam. There are three main ways to work this seam.

Mattress Stitch version 1
Thread a tapestry needle with matching yarn. If you left a long tail at the beginning of your knitting, use it to begin the seam. When you stretch the knitting slightly sideways, you will see a bar between the first and second stitches from the edge. Insert the tapestry needle under the first bar on the left, and pass the needle under it and back out. Insert the tapestry needle under the first bar on the right, pass the needle under it and back out. Repeat this process to the end of the seam.

Mattress Stitch version 2
This is worked very similarly to version 1. Pass the tapestry under 2 bars between the first and second stitches from the edge. This version works better for thinner yarns. It shows more when the seam is under stress (the fabric stretched widthwise, for example.) Most people prefer version 1 when seaming anything thicker than DK or sport yarns.

Mattress Stitch version 3
This is also similar to version 1. It is done half a stitch from the edge. There is a bar of yarn in the center of the edge stitch. Pass the tapestry needle under 1 bar in the center of the left edge stitch; take the needle all the way under and back out. Pass the tapestry needle under the bar in the center of the right edge stitch. Repeeat this process to the end of the seam.

Regardless of which seaming method is used, there will be yarn ends to deal with. The preferred technique is to work them into the seam allowance, whenever possible. Thread the yarn tail into a tapestry needle; sew through the seam allowance on the inside of the garment for approximately 2″. Stretch the fabric slightly so that the seaming yarn relaxes; clip the yarn, leaving a scant 1/4″. If there is no seam allowance, thread yarn tail into a tapestry needle and sew through the purl bumps on the wrong side of the fabric. Stretch the fabric and clip the seaming yarn.


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