For this petticoat I used 3.5m of cotton lawn. Yes, 3.5m for an underskirt for a 4 year old. Beat me about the head if you like - I know I deserve it! I started by measuring her waist and deciding how long I wanted the petticoat to be. She has an irritating habit of pulling anything with a waistband down below her belly button, so I had to allow for that too. I took 9cm off the length measurement (to allow for the addition of a waistband) and cut strips of lawn to the correct depth right across the width of the lawn. I cut four strips - these would be the body of the skirt. I then cut another 9 strips that were half the depth of the first lot. These would be the ruffle. Finally, I cut two strips 20cm deep. I joined the body strips to each other and the ruffle strips to each other and started hemming. It is a lot easier, believe me, to hem both strips now, before you start ruffling. I used a narrow zig zag stitch with the narrow hemming foot that came with my machine - the lightweight cotton lawn just skimmed through it beautifully. If I'd had to press, pin and stitch, I'd still be at it now! Just do the bottom edge of the skirt body, but both top and bottom of the ruffle.
Then came the fun bit - ruffling the short-strip ruffle. I used the pleating (number 6) setting turned up to its highest, and set a short stitch length - I wanted the pleats to be almost doubled up, so as to maximum the ruffle. I then sewed the ruffle, can-can style, to the skirt body, lining up the two bottom hems. Don't worry too much if the top edge has to undulate a bit to get the bottom even - nobody will notice, not even you!
I wanted the skirt body to fold out into ripples, rather than bunch out from tight gathers. I therefore used a technique I had learned when making a dressing-up classical tutu for Laura (I know, I know - sometimes even I have to despair at myself). Anyway, this technique on stiff tulle will create a skirt that will just about lie horizontal a la the magician's floating lady. On drapey cotton lawn, it creates satisfyingly foamy ripples. And I will demonstrate it to you now..
Grip the fabric in your left hand and fold it from back to front across your thumb.
Fold it back on itself and grip the three layers firmly between finger and thumb. The folds should be about an inch long - just eyeball it, you have dozens of these to do and only a masochist would measure each one with a ruler. Continue the front fold, sending it round the back...
Catch that fold too,
and then send it back round to meet the front again. And there you have it - a beautiful double pleat. From the top it should look like this:
Gorgeous isn't it? Stick a pin in it to keep it nice and continue pleating in this way until you run out of skirt body. Machine baste along the top of the pleats. Then join the two waistband strips (remember them?), and attach the top of the skirt body to the waistband, right sides together. Press the seam so the seam allowance is pointing up to the waistband.
From the front, the waistband seam looks like this:
Now you can join the skirt so it's a circle. I just put the skirt right sides together, making sure the edges of the ruffle would be caught in the side seam, and serged from the top of the waistband down to the hem. Press the seam. Cut some waistband elastic to the right length and iron a narrow hem into the top of the waistband. Fold the waistband in half lengthwise so that the hem meets the waistband seam. Press the fold and pin a casing into place, about an inch from the top of the waistband. Do a line of stitching along the pin line, leaving a gap so you can feed the waistband elastic through using a safety pin. Join the two elastic ends, being sure not to twist them. Stitch the gap in the casing. Then stitch along the waistband seam to catch the hemmed edge, like so: