The dreaded sleeve cap.

Guys, it’s going to be a long, long winter unless I can think of something to talk about that’s not secret! I’m still frantically knitting over here, and getting more and more excited about my upcoming trip to Rhinebeck. I’m teaching two classes on Saturday, and I’m a square in the always-fun Rhinebeck Bingo, and staying in a great house with my bestest buds. Couldn’t be better. Seems pretty likely that you won’t see me again until I return from the festival…

…So until then how about a little bit of technical talk about sleeve caps? Anyone who has taken my class knows that I’m pretty fanatic about set-in sleeves and sweaters done in pieces. Seams are magical things, transforming this stretchy, sometimes unwieldy, with-a-life-of-its-own fabric into a structured and well-fitted garment. The number one response I get to this opinion is that everyone hates setting in sleeve caps and they never come out right.

So I thought I might share how I do them. I took some snapshots of the latest sweater I put together (sorry, can’t talk about it yet) with the intent of walking you through the process.

The first thing to recognize about sleeve caps is that some modifications to your sweater will cause them not to fit. The length of the curve around the top of the sleeve cap must be the same as the length of the armhole length on the front and back combined (within an inch, say). So if you change the armhole depth, or your row gauge is off, your sleeve caps might not fit.

That said, here’s how I go about things: First, I seam the shoulders and lay the body of the sweater and sleeve out as shown. Then, I use openable stitch markers to pin the center of the sleeve cap top to the shoulder seam, and to pin the edges of the sleeve cap to the armhole shaping edges:

The stepped bind-offs at the armhole edge should match the initial bind-offs on the sleeve caps for most sizes (in some plus sizes, the second bind-off on the armhole is much longer than it makes sense to use on the sleeve cap. The first bind-off should always match exactly.) So next, I pin those:

I then ease and pin the rest of the sleeve cap together, about every inch or so, all along one side. I pick the whole thing up and lay it flat, checking my work on the first side.

Repeat for the second side, and lay the whole thing flat. You’ll notice at this point if there’s any weird puckering or anything else you need to adjust. (If your sleeve cap doesn’t fit exactly, this is the point at which you should spread the discrepancy in length evenly over the whole cap for the best chance of a smooth finish.)

Then, it’s time to seam! I use mattress stitch. When I’m knitting the sleeve cap, I always make sure to do my decreases 1 st in from the sides. This gives me a nice even edge all around. Typically I use a long tail from my sleeve cap bind-off to seam the edges and start at the top of the cap. This sweater was knit in tweed, though, so I needed to use a separate smooth yarn for seaming. So I started at the underarm bind-offs.

I work about an inch of mattress stitch at a time, loosely, and then pull everything snug. Repeat carefully all around the sleeve cap, making sure you keep the fabric even with the pins.

And that’s basically all there is to it! The only thing with mattress stitch is that you need to make sure you’re keeping the same number of stitches inside the seam at all time–that is, don’t jump “columns” of stitches when you’re seaming. For horizontal fabric, go under the “V” of exactly one knit stitch. For vertical fabric, make sure to pick up only that little bar:

If you take it slowly, the seaming shouldn’t take much more than an hour per cap. And given the way set-in sleeve sweaters fit, that’s a totally worthwhile investment!

20 thoughts on “The dreaded sleeve cap.

  1. What a helpful post.

    I’m looking forward to seeing your designs next Spring, how exciting to have so much secret knitting going on.

  2. That’s great – thanks for this. An hour… that may be why my only sleeve caps so far didn’t go so great – I didn’t take anywhere near enough time!

  3. I’ve started using Norah Gaughan’s method of starting the seaming at the top of the cap using a long piece of yarn (saving the second half up there to seam down the other side). That way, any slight wonkiness can be concealed in the underam. I’ve also found it useful to use a sloped bind-off at the bottom curve of the armscye, too. I feel geekily pleased with myself when a set-in sleeve works great! 🙂

  4. Lovely clear instructions – thank you! I use small hairclips instead of pinning; those tiny ones that look like little claws with hinges (not sure what they’re called). They’re supercheap, and allow the seam to open up to check for puckering.

  5. Thanks for addressing this. It seems we are very similar in how we set in sleeves. I am now thinking maybe the red Petrea had too small a sleeve cap so that it rolled to the larger armhole.

  6. I haven’t knit a sweater in a while, but when I do again, these instructions will be very helpful. Thanks!

  7. What fabulous instructions, thank you. I’m an odd bird – I don’t mind seaming at all. But I’m also not great at it so it’s always been hit-or-miss if it looked good. I’ll be coming back here for a refresher if I ever get to some of the sweaters on my list!

  8. That’s pretty much how I do it… though you bring up some of the finer points that I sometimes forget. Thanks Amy!!

  9. These are great, I love the look of set-in sleeves, so any and all tips are appreciated. Thank you!

  10. THANK YOU for this tutorial. I am in nearing the end of two sweaters with set-in sleeves.

  11. brilliant!! now I need to have a side bar with you on how to DESIGN said sleeve caps 😉 Hope to see you at Rhinebeck!! I’ll be there Sunday!

  12. Great instructions – thanks Amy. I don’t mind seaming but almost feel like a geek admitting it as there are so many seamless patterns around (LOL). I’m always a bit concerned that these won’t have the same body/ structure of a seamed garment.

  13. I heartily agree about set-in sleeves: they are sooo flattering when done right, especially for petite people. I find that it really helps if you have a good selvedge st so you can really SEE what you are doing. My personal fave is the slip stitch garter edge: on every row, slip the first st knitwise and knit the last st.

  14. oh!! I am most definitely going to want to refer back to this post. Thanks for the super-helpful explanation and pictures!

  15. How did you know that I have two sleeves to set in this week? Great tutorial. Thanks for the detailed instructions. I’ve learned more knitting from you than anyone!

  16. […] the best tutorials on knitting for your body type, and now she’s got a detailed tutorial on sewing in sleeve caps. My approach is a little different, but I think her’s is a winner, so if you’re afraid […]

  17. Thanks, Amy! I put a link to this tutorial up on my blog so I can refer back to it often. Very clear instructions so maybe I won’t dread that sleeve cap anymore.

  18. […] A great tutorial on something most sweater-knitters dread by Amy Herzog Designs. […]

  19. […] Seaming Tutorial – great tutorial on how to seam the sleeve […]

  20. Hi Amy,
    Thanks for this great tutorial. Are you able to reveal now what project it was, and what that gorgeous purple tweedy yarn is?
    Cheers, Sarah

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