Ok, I've had these pictures sitting there for months... so I finally decided to write up this tutorial! Woohoo! Here's how I repair the elastic in a serged edge diaper. Our subject today is a Kissaluvs fitted. I've also repaired Mudpies, First Class Baby AIOs, and others I can't remember right now. You'll need a seam ripper, some replacement elastic, and a serger or sewing machine. Yes, you can do this with a sewing machine but the edge you open won't look exactly the same anymore. You'll be closing it back up with just a zig zag stitch. It's still perfectly functional though!
Start by ripping the stitches out of the back edge of the diaper, about the same length as the back elastic. Pay close attention to the straight stitches, there may be either one or two rows of them, and you'll have to rip them out in addition to the overcast threads.
Once the diaper is opened up, rip out the stitching holding the elastic in place. You'll probably be able to see where it was stitched in place, but you can mark the ends of the elastic with a fabric pen if you like. Turn the diaper inside out and carefully remove the stitching holding the leg elastic in also.
Measure the old elastic and cut new elastic to fit. This is where it gets a little tricky, but I've found if you use braided elastic you can get pretty close-to-original results. What I do is stretch the worn out elastic to its max., and measure it. Then, stretch new elastic to the same length and cut. Since you can't measure the worn out stuff un-stretched anymore, this method seems to work well. Be sure you are using an elastic that is made to withstand high temperatures and chlorine. There are two types of elastics, one says it will withstand up to 200 degrees, the other suggests hand or cold washing. Swimsuit elastic is a good choice too. My favorite elastic is Lastin, but figuring the exact amount you need can be difficult depending on the amount and thickness of the layers of fabric. So we're using Stretchrite braided here.. 3/8".
I'm starting with one of the legs here. Pin the ends of the elastic in place, the pins should be on the outside of the diaper, and the elastic inside will be pinned to just one layer of material right now. I leave about 1/8" - 1/4" elastic beyond the pin.
Now, from the outside of the diaper, carefully lay the layers of fabric straight, and reinsert the pin through all layers of fabric, still holding the elastic in place.
Now, carefully stretch the elastic out so the fabric lays flat. An extra set of hands would come in quite handy here. I put one pin/end of the elastic under the bottom of my sewing machine and stretch the elastic, holding the other pin in my right hand. Using my left hand, I feel where the elastic is laying in between the layers of fabric, and move it into place. I pinch it tightly or hold it against the cutting mat, then pin it with my right hand. I like to place the first pin in the middle of the length of elastic, then reduce the distance by half with each new pin to keep the stretch the same along the entire length. Use the original placement of the elastic as a guide, since the distance from the elastic to the edge of the diaper may vary with each brand. Continue positioning the elastic and pinning it in place while stretched until you reach the other end. I place pins every one inch or less.
ETA: VERY IMPORTANT!! When using Lastin, the pins should not go through the lastin as they do with the braided elastic, the pins should go through the fabric on either side of the lastin, creating a path for it to lay but not piercing the elastic. When using Lastin, I pin the ends then pinch the ends when stretching it to sew so that I am not putting stress on the pin holes in the ends.
This is what the first leg should look like after the elastic is pinned in place. You can tell by the gathers if you've stretched it equally along the length. If one area looks too gathered or not gathered enough, now is the time to fix it.
Now, place the end of the elastic under the presser foot of your machine. Your needle should make the first stitch right behind the pin (remember that extra 1/8" - 1/4" elastic beyond the pin?). I prefer to use a 3 step zig zag. It looks nice and it is the best stretchable stitch for holding elastic flat in place. It is necessary to use this stitch if you are using Lastin. If you don't have this stitch, a wide, long regular zig zag will work with braided elastic. I set the machine to 0 length, regular width 3 step zig zag so that it stitches from left to right and left again without moving forward. This holds the end of the elastic in place. Then set it to regular stitch length and slowly sew down the elastic. It should be very easy to follow where the elastic is since your pins are placed in the elastic. Stretch the elastic as you go, and finish with the 3 step zig zag in place at the other end of the elastic.
There, that wasn't too bad. :) Your diaper should now look like the one pictured below. Now, go ahead and repeat these instructions for the second leg before you move on.
Next, we'll be doing the same thing with the elastic in the back of the diaper. This one is a little easier to be sure you are pinning it straight since the back is open. Place the pins at the ends of the elastic, leaving a bit beyond the pin for that first stitch to hold it in place.
The edges of the fabric may want to curl a bit, and they may look stretched out since we removed all the stitches here, so take your time to be sure the fabric is laying straight as you pin the elastic in. Here I am starting with one end of the elastic held under the machine (or call your extra set of hands back in!), stretching it out, and placing a pin in the center of the elastic.
Because the fabric curls and stretches here, it may be easier to pin the elastic to the lower layer of fabric first, then line up the top layer of fabric.
Pins are in place in half of the elastic. Continue carefully laying the fabric straight, edges matching, with the elastic laying along the original stitching lines.
Once the elastic is pinned in place, stitch using a 3 step zig zag again.
Now that the new elastic is all done, we need to close the diaper back up. If you are using a sewing machine, set it to a medium to long length and width zig zag stitch, and sew along the edge so when the needle is down on the right side, it is just off the edge of the fabric, creating a false overlock.
If you are using a serger, carefully stretch the elastic as you serge along the open area. If you like, lower the blade so you don't worry about cutting into the fabric. Tie the extra thread off so it doesn't come unraveled. I like to pull the 2 needle threads seperate from the overlock threads, and then tie the two groups in a square knot.
Looks nearly new :) Pat yourself on the back.