As a bonus, I've also added a mini tutorial for making a bow out of the leftover waist tie fabric, since matching accessories are always fun. Sadly, in doing my wee bit of hand-sewing I was getting horrible nerve twinges in my wrist and fingers, so I think it's a sign that I need to avoid hand-sewing as much as possible. Let's hope that I can keep on with machine-sewing!
The main waistband alteration tutorial is aimed at those who have around an intermediate sewing level. You should be pretty confident with making gathered-waist skirts on flat waistbands, using a seam ripper, and optionally, with putting in a partial panel of elastic shirring.
The mini bow tutorial is aimed at those who have around a beginner to intermediate sewing level. You don't need to be hugely confident, and could probably even make this by hand if you don't have a sewing machine, but tools like sharp sewing scissors, an iron, deft fingers and some skill at hand sewing are probably useful.
Let's start with the alterations! The first step is to unpick the waistband from the skirt. The fabric on the left is the waist tie I'll be using to add a panel - if your skirt doesn't have waist ties, then you'll need to find some matching (or matching-ish) fabric for the extra panel insert. If it's going to be impossible to match, you can do what I did for the ETC skirt I'm wearing in this post and simply make an entirely new waistband, but in that case, this tutorial isn't necessary :D
I haven't shown the entire process in pictures, but once your waistband is unpicked, press it all flat to remove any creases from an old shirring panel. Decide how long you'll need your new waistband, and divide that measurement in half - this will be the front of the waistband. Mark the side-seam point on the band using a pin or tailor's chalk. For example, if you want to make a new waistband to fit 30", measure 15" from the end of the waistband which has the buttonhole, and make a mark at that point.
Measure from your marked point to about an inch from the other end of the waistband. We're leaving an inch because you'll need overlap for the button or hook-and-slide fastening. Find the centre of that length, and cut the waistband vertically at that centre point. For example, if the remaining length (less one inch) of the band is 12", cut it vertically at the 6" point.
Re-space your waistband and measure how much of a panel you will need to insert. Remember that you'll need to give at least 0.25" on each edge for seam allowance, probably a little more (your mileage will vary depending on how comfortable you are with small seams). If you're doing a flat panel here, then you'll just need to measure the extra width needed plus seam allowance. If you want to add elastic, then add another two inches or so for shirring.
Here's my panel all cut out - for the height measurement, open out the existing waistband and measure the width.
Pin your new panel in place, then sew it and press the seams open. I haven't interfaced this panel because the elastic I'm adding will give enough stiffness, but if you want it as a flat panel, interfacing is a good idea. This panel has now been inserted into the centre back of your waistband strip.
Re-gather the skirt to the new waistband length. It won't be quite as gathered, depending on how much extra width you've added, but most brand skirts have enough fullness to easily accommodate an alteration of a few inches.
Measure in and then sew your elastic strip into the new shirring channel, if you want a shirred panel. Everyone seems to have different ways of doing this, but my method is to fold it into the channel, sew it secure down one of the new panel seams, sew the channel closed, and then pull the elastic down to the other seam so that it can be sewn securely down that seam. I also like to add a centre line of stitching through all waistband layers, running down the elastic parallel to the gathered skirt, as this keeps the elastic even and stops it from bunching.
Once the elastic panel is secure, top-stitch the rest of the waistband again. You can either stitch in the ditch, or top-stitch very close to the gathered edge.
Here you can see that the front waistband looks basically as if it's never been touched, while the new panel in the back is also quite natural-looking and doesn't look like a home alteration. Using shirring for the added panel means that the seams for the added piece aren't that noticeable, and if your added-panel fabric doesn't quite match, shirring will help hide that too.
Once you've tied off all the loose threads, your skirt will be ready to wear :D I'm totally looking forward to wearing it tomorrow, perhaps in a slightly mori-inspired coordinate.
Using waist ties for a waistband alteration will leave you with ties that can no longer be used for a waist bow, but can easily be turned into pretty accessories. The cream grosgrain ribbon bow above is one I detached from a BtSSB dress and often wear bobby-pinned into my hair, and I wanted to make one a similar size.
To make a similar bow, cut two rectangles of fabric - one 4" x 3.5", and one 4.5" x 3.5".
Fold your rectangles in half, right sides inside, and pin down the long edge. Sew this edge, leaving a gap in the middle (if you look at the larger rectangle, I left a gap in sewing between the two pins). You will now have two tubes of fabric, which have a hole in the long seam. Roll the tubes so that this seam runs down the centre of the rectangle, then press flat. Pin and sew the side seams closed. Turn your rectangles inside out through the hole you left in the first seam, and press flat. You can slipstitch the holes in the long seam closed if you like, but they basically get hidden once it's turned into a bow, so I didn't bother (because I am Lazy Like A Lazy Thing).
Cut another strip of fabric 3.5" long and 2" wide. Fold the long edges in about 0.5" on each side and press. Pinch your rectangles in the centre, and wrap your strip of fabric around it until you have a pretty bow. Fold in the raw edge of the centre strip, then fold again and pin it into the back of the bow. Hand-sew your bow secure.
You can just bobby-pin this into your hair, attach a hairclip, or even sew on a brooch pin and wear this little bow as a cute brooch or bowtie, but I had a spare headband so I decided to make it into a cute, subtle side-bow.
I don't tend to wear matching hair accessories anymore, but I think this is subtle enough that I'll have fun coordinating it. Making a headbow is very easy - you simply have to cut and sew a tube of fabric long enough to cover your headband, then slide in the plastic band, fold and sew up the raw edges at the bottom, and sew the bow on in place.
Good luck with the tutorial! If you have any questions, please do ask and I'll do my best to explain. :)