One of my favorite joking statements is, “I’m falling apart, won’t you join me?”

Our pin loom squares, while not falling apart, still need to be joined if you want to produce some sort of finished product. There are many ways to join squares: duct tape, glue, sewing machine . . . But for a more organic result, you’ll most likely want to use yarn. And why not use those pesky ends that need to be woven in anyway? (My friend prefers to not use yarn tails because of the danger of puckering the squares as she pulls the stitches, so that’s something to consider.)

Mattress Stitch

I’ve heard this method called “Mattress Stitch,” so that’s the name I’m sticking with (till someone comes along and corrects me). I first saw it on someone else’s blog, but I wanted fuller instructions (like, how do you join the sides and corners?) and slightly better photos. I hope these are better!

Let’s start by looking at the square.

By definition, a square has four corners. A three-layer-warped, horizontally woven pin loom square will have four different corners. Corner 1 (Cr1) has the beginning tail with two loop pairs on either side of it. Cr2 is the most distinctive corner with its two scrunched-together loops. Cr3 has three loops (this will be significant at the beginning of Part 2). And Cr4—oops, it looks just like Cr1! So guess what—it doesn’t really matter which way you turn the squares as long as Cr2 is at the bottom right and Cr3 is at top left. However, on many squares (patterned squares) there is a right side and a wrong side.

If you want to use the yarn ends at Cr1 and Cr4 for joining, you’ll want about 3/4 of a wrap around the pins for joining purposes.

About 12 inches (30 cm) of yarn at each corner is plenty

It’s easy enough to attain this length at the beginning, just leave that much yarn hanging at Cr1. I wrap my L4 yarn 5 times around the pins before cutting/weaving and that always leaves me plenty of yarn for joining, without a lot of waste.

(Of course, I never leave that much yarn at the beginning because I don’t think that far ahead. For the squares in this project though, I measured off a little more than one length of the pins and that seems to have been just enough to eke out a join along one length.)

You can, of course, join the squares in any order you want to. This tutorial shows a horizontal join in Part 1. Part 2 shows how to deal with corners and making vertical joins.

Here are the materials and layout you’ll need.

Lay out your squares so Cr4 yellow is directly below Cr2 blue


I like a blunt tip needle with a large eye. I’ve included the weaving needle in the photo only for comparison (I don’t recommend it for joining), and the needle threader because I love to use it. Place your squares one above the other so Cr4 of the yellow square is directly below Cr2 of the blue square.

Thread your needle with the yellow Cr4 yarn end and take the needle beneath Cr2 blue, then up through the loop at that Cr. The instructions I initially received were to take it through only the single loop nearest you which is probably correct, but I generally take it through the intersection of both loops.

Take needle through Cr2 loop from beneath

Now stitch with the needle above the squares. You’ll work back and forth across the length of each square. You’ve caught the blue square, so now go back to the yellow and catch the first two warp loops at Cr4 (3-4 side).

Go under the central intersection of loops

Take the needle under the intersection of the two loops.

Path of the needle when picking up loops—over the outer half of each loop, under the inner halves

Now go back to the blue square and pick up the next set of inner loops. Then go back to the yellow—back and forth all the way across. Gently pull the yarn tail to snug the seam closed as you go. Don’t pull too tightly or you’ll cause the yellow square to pucker. Each set of yellow loops will nest between the corresponding blue loops.

Continue picking up alternating sets of loops all across the two sides

***I received a request from a reader for an exploded view of the mattress stitch, so here it is.

Mattress Stitch—shown without tightening the stitches

When you get to the last set of yellow loops, go through the horizontal two loops at Cr3. Then go across to Cr1 of the blue. If your beginning yarn tail is worked in already, you may have two loops there. If not, just take the needle from beneath and up through the single loop (as you did at the very beginning of this row when you joined yellow Cr4 to blue Cr2).

First photo shows going through two loops of blue Cr1 if end is worked in. If blue Cr1 end is NOT worked in, take needle under the single loop—as you did at the beginning of this row.

That’s the basic way to join the squares. You can see that you still have plenty of yarn left. You can work that end in or use it to join the yellow 1-3 edge to another square’s 2-4 edge.

This is the way the join looks across the back. On the front you’ll get a flat join; on the back there’s a slight ridge.

Back view of joined squares


Let’s say you’ve got four squares—two pair joined along the horizontal edges (as shown above). Now you need to join the vertical edges. Since this post is concerned with using yarn tails to join squares, that’s what I’ll show in the demo. If you’re not using yarn tails, you can decide to join the squares in any order you’d like.

We left off at a Cr3-to-Cr1 join, e.g. green up to white.

The last stitch of the horizontal join, described in Part 1, is the first stitch at the corner join—from Cr3 up to Cr1 (green yarn catches first loop of white 1-3 edge). Next, take the needle across to the top Cr2 loop of the blue square (needle comes from beneath when catching single loops). Go down to beige square and catch first loop of Cr4 (2-4 edge). Finally, go back to green square and catch the first loop of the Cr3 three-loop group. (There are three loops at Cr3; we used two of them already when we joined the 3-4 edge of the lower square to the 1-3 edge of the upper square.)

Gently snug the corner join closed. Now come from the green square back over to the beige square and, taking the needle from above the work, go through the intersection of the first two loops at beige Cr4 (2-4 side; we already used the first loop once, but we’re going through it again).

Beginning the lower vertical join

Continue the vertical join as you did the horizontal join—going back and forth through the intersecting weft loops: green to beige, beige to green.

When you come to the last stitches, you’ll see how neatly Cr1 fits into the Cr2 niche, completing the straight line.

You can work in that end now or save it till later and have a big, fun end-working-in party!

Now we’ll go back up to the four-corner region for the second half of the vertical join of these squares. Start by turning the work over to the back. In this demonstration, I’m using the just-barely-long-enough white Cr1 yarn tail to join the blue and white squares.

From the back of the work, poke the needle up through the top loop of blue Cr2. (Remember, we already used this loop once when making the corner join, but we’re using it again now.)

Back view of beginning the second vertical join

Turn the work to the front. Since we’re coming from the blue side, we now cross over to the white and pick up the first intersection of loops at Cr1. Continue joining—now we’re old pros.

From blue Cr2, go across and pick up white loop intersection.
Second photo shows that first stitch pulled tight.
Third photo shows third stitch—into blue loops.

The end of this vertical join picks up the last stitch of white Cr3 and joins it to blue Cr4. Technically, you should only need to pick up one of Cr3’s loops (since the top two will be joined horizontally with another square), but I picked up both (it’s hard to remember EVERYTHING).

When your joins are finished you can work in the ends. As I pointed out before, the back of your work will have slight ridges along the joins.

Back view of the work

Your corners should be snugly joined so pressure won’t pull them apart from each other.

Sooooooooooo, I’m not falling apart, but won’t you join me in joining squares?


14 Thoughts on “Joining Squares — mattress stitch

  1. Nancy M on 17 October 2017 at 4:51 AM said:

    Bravo Sue! That is the best, clearest, most well photographed instructions I have ever seen on joining!! You really have a gift and the whole pin loom,weaving comminity is lucky to have you sharing with us.

  2. Great explanation. Thanks

  3. Kate Bales on 23 October 2017 at 4:05 AM said:

    Thank you Sue!

  4. This is so amazingly helpful! Thank you for such clear instructions. I really appreciate it!

  5. Excellent tutorial – thank you! One question, you don’t think it’s necessary to do a knot or anything at the end of joining, or maybe before working in the ends? I am worried that with use, the joins will wiggle out and squares will start separating.
    Thank you for this website, so many good things to discover! I have just started doing some of your patterns, too. You are my weaving go to expert!

    • Sue Burton on 22 November 2019 at 10:39 AM said:

      Thank you for the kind words!
      About knots–personally I don’t like them in needlework. Yarn has a tendency to bind to itself–even acrylic yarn does this. (Try unweaving one of your squares after a couple of days.) When sewing in the ends, I generally double back on the seaming, so the yarn isn’t likely to work loose. (Try picking out one of your sewn seams.) However, I know that yarn ends do wiggle out of place and poke out of the work, but tying knots won’t rectify that problem. I’ve come to accept this as part of the work. Tying knots won’t keep worked-in ends from poking out. I really don’t think the seams will loosen and fall apart, especially if you’re using wool, but it depends on the type of use your woven object will get. If durability is a concern, you could try reinforcing your stitching on the sewing machine.

      • Thank you so much! Makes sense. I don’t have a sewing machine so I’m just going to trust the weave and your expert advice! Thanks again for answering my question so quickly!! You’re the best!

  6. Pingback: Joining — Double Edge Whip Stitch Method – Adventures in Pin Loom Weaving

  7. Paula Freeman on 3 May 2020 at 6:07 AM said:

    Thank you for the clear explanation and photos! My daughter is obsessed with pin loom and needed help with how to sew them together. You made it so easy to understand I see now how to show her! Thank you!

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