Have you been directed here after reading the instructions that come with your PDF purchase, or watching my YouTube video on sewing the armholes? Welcome. This is the optional step mentioned in Step 4.
If you're looking for the method outlined in the alternative instructions, you can watch that video here instead.
This blog post is all about the armholes of the Weiland Tank.
This sewing pattern is designed for knits with 2 way stretch and a stretch percentage of 40% or over. I've also recommended using a knit with good recovery for this style - as is it quite fitted and you don't want your top getting stretched out and saggy after wear or during sewing.
What does good recovery mean? It means the fabric easily bounces back to it's original form after being stretched. This is easy to test when you're fabric shopping in person - but I know these days a lot of us shop for fabric online and it's often too late to return fabric after it's been cut off the roll.
If you've found yourself with a knit fabric with poor recovery, this may affect how your Weiland Tank sits. The neckline and armholes may get stretched out as your sew everything and leave you with gaping or warping... which we don't want.
One way to help this is by stabilising your seams with clear elastic.
So you've just sewn your armholes together, popped the top on to see how it's fitting and found that there's a bit of gaping?
Unlike woven tops, fitted knit tops do not usually have bust darts, and the excess fabric where the dart *would* be is cinched in by binding. But this design is lined - it does not have binding.
So instead clear elastic can be sewn into the seam allowance to bring any excess fabric in (if necessary). Luckily I haven't had the need to do this for any of my samples, but I've done it here on this one to show you how I would do it.
This is how my top looks from the right side now that the armholes have been sewn.
This section of the armhole is the most curved and therefore the most prone to getting stretched out. This section is where I will be sewing the elastic into the seam allowance.
Now that the neckline and armholes have been sewn, it's impossible to turn the top fully inside out. So I've turned it out as much as I can, so you can see the curve of the underarm on each side - where I'll be sewing the elastic.
I've pinned where I'm going to start sewing from.
Make sure to give your elastic a couple of stretches before sewing it, to 'warm it up' for lack of a better term. I've also given myself a tail of elastic to hold onto while I sew the initial stitches in.
I've used a zig zag stitch to sew the elastic onto the lining side of the seam.
If you just want to stabilise the seam/keep the curve from stretching out - then you only need to hold the elastic taut as you sew it on.
If you're wanting to reduce gaping, then it's worth making a note of how much excess fabric you want to cinch in, and ensuring your elastic is marked to size accordingly. You will need to stretch the elastic out as you're sewing it onto the fabric to ease in the excess fabric.
Trim the seam allowance down if you haven't already.
Understitch the seam allowance to the lining around the curve of the front and back armhole.
Give it another light press, making sure the lining is tucked slightly away and shouldn't be visible from the right side. (be careful of the fact that you now have plastic in the seam and may need to change your iron settings).
And that's how it will look from the right side!
Another great resource for perfecting armholes in knit fabric is this post here from Seamwork.
Hope this helps.