I cut 25mm knit elastic to my waist measurement minus a couple of centimetres, join it in a circle, quarter it and stretch it in as I sew. On the table it looks right. After an hour of wear it has slid down and folded over on itself. Is this a length problem or a construction problem, and does the number change between a woven skirt and jersey trousers?
The rolling is a construction issue and not a length issue. 25mm elastic in a casing with nothing holding it flat will fold along its length every time, especially in a soft knit. Either stitch through it in two or three rows to hold it open, or use a wider, firmer elastic, or add a channel of stitching down the middle of the casing. Length changes how tight it is; only stitching changes whether it folds.
I killed several waistbands before I realised I was overstretching the elastic while sewing. Stretching it hard under the presser foot to make it fit the fabric takes the recovery out of it permanently, so it measures right and behaves like a limp band by the third wear. Stretch to distribute between quarter marks, never further, and let the feed dogs do the work.
Also worth knowing that some cheap elastic dies in the first wash regardless of how gently you treat it. If it comes back from a hot wash noticeably longer, that was the problem all along.
Slightly different diagnosis: your elastic may be fine and your rise may be short. If the waistband ends up sitting below the narrowest part of your torso, gravity plus a hip curve will walk it downwards and it will roll when it arrives somewhere it does not fit. Measure where the finished waistband actually lands on you versus where you measured, and I would bet there is a difference.
Woven skirt and jersey trousers are not the same job. Woven needs enough ease to get over the hips with the elastic fully relaxed, jersey does not.
@thriftedtweed · last mo. · 2 replies
Stop measuring and start fitting: wrap the elastic itself around your body where the waistband will actually sit, pull it to the tension you want to wear all day, pin it there, and that plus seam allowance is your length. For soft knit elastic that usually lands me somewhere around ninety percent of the body measurement, and for firmer braided elastic it is less reduction because it has more grip - but the pinned length is the truth and the percentage is just the sanity check. Two other things: elastic sits where the body is narrowest, so if the garment wants it lower than your true waist it will migrate no matter what length you cut.
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@seamripper_sol · last mo.
Pinning it around yourself first felt like cheating the first time I did it and it has never failed since. Do it over the clothes you would actually wear it with, not over bare skin.
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