It very much depends on what you’re trying to achieve. Fundamental to this is the fact that the entire garment depends on, hangs off, the shoulders. So, what is the garment like? What is the construction? How wide are the shoulder seams, and what are the dimensions and weight of the body of the sweater which hangs off those seams?
You can rule out some constructions, depending on the sleeve treatment. Yoke sweaters don’t have shoulder seams:
They’re just knit in the round, reducing as you approach the neck.
Raglan sleeves usually don’t have a shoulder seam, because the ‘shoulder’ is built into the sleeve:
Ditto for saddle shoulders, which are often seen on Aran/fisherman/ cabled sweaters, such as Katherine Dames’ An Aran for Anne:
A saddle-shoulder sweater does need seaming as such, but the strap from the sleeve is sewn to the top of the body.
Then there’s the drop shoulder. You’ll usually find this on knitted garments that are fairly ‘unstructured’ – not fitted or tailored as a suit would be. They’re loose, over-sized, relaxed – they have ‘positive ease’, in the jargon. This generally means a lot of wool/weight is hanging off the shoulder seam, but the shoulder seam itself is substantial:
This is a style you’ll probably be seeing all over the shops this winter – a very sloppy Sloppy Joe style, possibly called ‘Hygge’ in the more fashion-conscious boutiques. Note that the shoulder is so wide that the sleeve only begins at the elbow.
Of course the fitted sweater is a thing, and very popular too. Here’s Ruth Garcia-Alcantud’s After Five Sweater:
This has a ‘set-in’ sleeve, a very tailored feature that you’ll see on suit jackets, and a relatively short shoulder seam.
There are a few variations on these four shoulder/sleeve treatments – for example, a raglan may be modified to stop before the collar, and the remainder must be seamed (perhaps to add a Henley or placket collar) but these patterns will usually contain instructions for seaming.
So: the methods I would recommend for the two shoulder-seamed sweaters (drop and set-in) are as follows.
Drop shoulder: because these are fairly heavy, with a lot of wool in the body, I recommend the sturdy, inflexible mattress stitch. This won’t stretch as grafting does.
You might also find it useful to sew on twill or bias tape to give the seam extra strength.
Mattress stitch is also the best seam for saddle shoulders, especially if it’s a heavyweight Aran. Here’s another video demonstrating the technique for this:
Set-In shoulder: These are usually found on fitted sweaters, which means less weight on the shoulder seam. For these, you can graft the seam. There’s several methods:
The standard way, with a tapestry needle –
or the knitted, no-sew way –
And, new to me, a variation on the tapestry needle method which is so, so much simpler than either of the above –
I’m gonna have to design something just so I can use this…
There’s a third technique which doesn’t get as much press because it’s often bulky, doesn’t sit well, and can irritate tender skins. But it does have its uses, especially when the seam needs to be very, very sturdy indeed. I would tend to use it only for outerwear garments, though it’s also a good choice for sleeveless sweaters, especially with thin shoulder seams like Melinda VerMeer’s Laurelhurst:
It’s the 3-needle bind-off:
Of course, you don’t need to listen to me. Maybe you want your Hygge sweater shoulders down at your wrists, or you can’t be bothered with all that in and out and back and front of Kitchener stitch. Maybe, like Melinda VerMeer, you want a clunky seam as a design feature. But these are the broad principles:
- Heavy sweater -> mattress stitch
- Light or fitted sweater -> Kitchener stitch/grafting
- Must not stretch EVAR -> 3-needle bind-off.