Mattress stitch is based on running stitch – a method used for basting and making other temporary seams in sewing. Why temporary? Because this seam is not strong.
When we put together a sweatier or make vertical seams in other knitting projects, we need the seam to be strong enough to withstand the stretch of the fabric.
We also need the seam to be elastic to make sure it does not constrain the knitted fabric. Running stitch and its cousin mattress stitch don’t have any elasticity, and that is another reason to look for a better alternative.
The easiest solution is to use the strong and elastic backstitch to seam our sweaters, cardigans and other projects. We discussed this option a while ago in this detailed tutorial.
The only drawback of this approach is the fact that we form the seam on the wrong side of the fabric, and don’t see how it looks on the right side until the seam is finished. In most cases the seam ends up to be neat, but sometimes we accidentally shift to a neighbouring column of stitches, and that shift affects the look of the seam.
I played with both seaming methods to find a way that allows us to get the best of both worlds – a strong elastic seam that we can make as we look at the right side of the fabric.
It turns out that we can achieve that when we follow just a few simple steps.
If you’d rather watch these steps in a video tutorial:
SETUP
Just as we do when we use the mattress stitch method, we are going to join horizontal strands between the edge stitches and the main fabric on one knitted piece to corresponding strands on the other knitted piece.
If those horizontal strands are not easy to see, it helps to pull the edge column of stitches on each piece away from the main fabric.
This way, we’ll make the horizontal strands more visible.
Place the knitted pieces next to each other so that the right sides of both pieces are facing you, and the bottom of the future seam is aligned.
Cut a piece of yarn that is at least three times as long as the future seam and thread this yarn into a wool needle.
To help you better see each step of the seaming process I will use a piece of yarn in a contrasting colour, but of course, in real life, we should use yarn in the main colour unless we want to add a glimpse of colour to the seam.
The first thing we should do is attach the yarn and join the pieces at the bottom. We do it in three simple steps.
SETUP STEP 1
Insert the wool needle from back to front under a horizontal strand that is the closest to the cast on edge of the knitted piece on the left.
Pull the yarn through leaving a tail that is just long enough to weave it in later on.
SETUP STEP 2
Now insert the wool needle from back to front under a horizontal strand that is the closest to the cast on edge on the piece on the right.
Pull the yarn through, but don’t pull it too tight. The pieces should stay relaxed and not squished together.
SETUP STEP 3
Finally, insert the wool needle from back to front into the same spot where you went in the setup step 1.
Pull the yarn through, but don’t pull too tight.
When we look at the join that we’ve just formed, we’ll see that the strands stretched between the two knitted pieces resemble the digit “8”.
This join is called “figure eight join” and it is a great way to tie two pieces of fabric without making a knot.
Now that we understand where this name comes from, take the working strand in one hand and the yarn tail in your other hand and pull them apart to tighten the join.
You can skip these steps if you use a yarn tail left after you cast on stitches. To avoid joining yarn within a seam, plan ahead and leave a tail that is at least three times as long as the future seam.
MAKING THE SEAM
As we make this seam, we will always pick two horizontal strands in the direction away from the bottom (“up”) on the piece on the right, and we’ll pick up one horizontal strand in the direction towards the bottom (“down”) on the piece on the left.
This is the basic logic behind this seam. Now let’s see how it works step by step.
STEP 1
We start with the knitted piece on the right.
Insert the wool needle from front to back into the spot that we entered in the setup step 2 and out of the fabric two horizontal strands “up” from the needle entry point.
Pull the yarn through and tighten the seam.
STEP 2
Take the knitted piece on the left, and insert the wool needle from front to back into a spot that corresponds to the needle exit point on the piece on the right. This spot will be two strands away from the “figure eight join”.
Then move the needle out of the fabric in a spot that is one strand closer to the bottom of the seam.
Pull the yarn through and tighten the seam.
STEP 3
Go back to the piece on the right, and insert the wool needle from front to back into a spot that is between the two strands that we picked up the previous time we worked with this piece. Then take the needle out of the fabric in a spot that is two strands away from the bottom.
Pull the yarn through and tighten the seam.
STEP 4
Now it is time to work with the piece on the left. Insert the wool needle into a spot that is one strand away from the strand that we picked up the previous time we worked with this piece, and take the needle out of the fabric in a spot that is one strand closer to the bottom of the seam.
Pull the yarn through and tighten the seam.
Repeat steps 3 and 4 going under two strands “up” on the right and one strand “down” on the left until you join all horizontal strands on one piece to the corresponding horizontal strands on the other piece.
As you pull the yarn through after each stitch, pull it quite tight. This seam is elastic even when it is tight, so there is no need to worry that the fabric will get puckered. It gives us the confidence to do whatever we need to avoid yarn slack between the knitted pieces.
Once in a while, align the pieces along the whole length of the seam to make sure the top parts of both knitted pieces stay aligned as we continue to join them. If the pieces are misaligned, adjust the seaming to compensate for the difference in length.
When the seam is finished, secure the yarn and weave in the tails. In the photo below, I didn’t hide the tails to help you see where the seam is on the right side of the fabric.
You will see that this seam looks a lot like a seam formed by the mattress stitch method – almost invisible on the right side of the fabric with a ridge formed at the back of the work.
But unlike the seam formed by mattress stitch, the seam we just made is elastic and strong. Even if we cut one of the strands that form this seam, the hole won’t grow nearly as fast as a hole cut in a seam formed by the mattress stitch method.
To make the seam less bulky, use sewing thread or a few plies of yarn instead of the whole strand of yarn. Or, join the horizontal strands that run inside the edge stitches instead of the horizontal strands between the column of edge stitches and the main fabric. This will reduce the bulk in half, but those strands are not easy to locate. Finding those strands could be worth the effort if your project is made out of bulky yarn.
SAVE IT FOR LATER:
This and 31 other in-depth tutorials are part of Knitting Collection #8.