I have gotten SOOOOO many questions on how I make my necklines. Well. It isn't a secret, but I haven't seen that many seamstresses that use my method. Personally I think it is great. For kids that have fairly large heads and small bodies, the necklines usually get very wide. And living in a cold climate you really want the neckline to fit snug around the neck, to avoid any gaps where cold air could sneak in.
The first thing you need to do is figure out which is the front and back. If you enlarge this picture you will see that the upper part is the backside that is matte, and the right side is slightly shiny. There are foldover elastics that doesn't look exactly like this, some have a scalloped edge, some have sequins, two matte sides or a deeper fold in the middle. These are the 5/8in (16mm), but there are all kinds, wider and thinner. I buy mine from Etsy or eBay. In Sweden it is also available from Bibbis textil. And if you're really local Knappkarlsson in Gothenburg have a wide variety as well.
Okay. Now you know the basics.On to the tutorial.
Trim your neckline so that you have an even cut, without any threads.
Next you need to figure out the length of the elastics. I measure the neckline and then cut 75% of the neckline. You can do it with a tape measure, but I lay out the elastics around the neckline (without cutting it!) mark the distance, fold it four times and cut off 1/4 of the elastics. Voila!
Fold on half with the right sides facing eachother. Sew a straight seam about 2mm from the cut. Make sure that you use short stitches (I use 2.0) and that you sew the entire way from one side to the other. I start at the upper end sew across, and then put in the reverse and sew the same seam again. That way I will only have to cut threads on one side.
Next it is time for some needles. I straighten out the elastics and put one in the middle. And on the shirt I fold the shirt on half as well to figure out where the middle of the neckline is. I put one needle at the back piece and one on the front piece. This is for a childrens neckline. For an adult neckline I usually use four needles on the elastics as well as the shirt.
Fold the elastics over the edge and pin it down. I put the seam of the elastics in the back of the neck.
I start sewing in the back and stretch as I go on. Make sure that you get the fabric all the way into the fold and that you stretch the elastics evenly around the neckline.
When you approach the back seam I trim my sizing lables and tuck them into the fold. Without removing the shirt from the sewing mashine!
And then you just sew the last few stitches. If you have a sizing label make sure that it stays in place. Snipp snipp with the scissors to cut of the two threads on the inside and two on the outside of the shirt.
There! All done! As you can see it ALMOST looks as if there are some wrinkles around the neckline. But, once worn it looks as it should do. Besides, after a few times when you have pulled the shirt over the head it will be a perfect fit. If you use slightly longer elastics it will eventually become to long and stand out from the neck or become slightly wavy.