Dear readers,
Mastering this one is essential because stretched edges happen all the time. Even when you cut carefully, handle your pieces well, and stabilise your edges correctly. Some fabrics just move. Some areas of a garment are more vulnerable than others. And sometimes you try on a half-finished garment a little too early (jeans without the waistband attached is a classic I have lived), and things shift.
Whatever happened, it is done. And the difference can be significant enough that pinning the two edges together and hoping for the best will not get you there.
Why stretched edges happen
Edges can stretch during handling (especially if pieces were not kept flat, see an earlier tip on this), during stay stitching if the stitching is done under tension, during fitting when pieces are tried on before they are stabilised, or simply because the fabric is bias-adjacent and responds to movement. Once an edge is stretched beyond what the seam allowance can absorb, you need to ease it back.
The technique
Pin the longer edge to the shorter one, distributing the excess evenly between notches. Use fine pins without plastic heads: they will be going under the iron.
Then apply steam generously and let the heat do the work. You are not pressing hard. You are introducing moisture and heat to encourage the fabric fibres to contract slightly and absorb the excess length. Hold the iron above the surface or use a pressing cloth, particularly on delicate fabrics.
Let the piece cool completely (pinned and flat) before moving it. Then sew with the eased side on top.
Where this works best
This technique is particularly effective for: an armhole edge eased into a fused facing (use the facing as your reference); a neckline into a facing or band; jeans or trouser waist into a waistband; the back shoulder seam eased into the front shoulder on tailored garments; and sleeve heads with minimal ease.
A note on fabric
This works beautifully on wool, which responds to steam and shrinks willingly. Cotton poplin is much less forgiving. The more a fabric can respond to steam, the more you will be able to ease back. On resistant fabrics, the answer is to be very careful with handling from the start, so that stretched edges do not develop in the first place.
Happy sewing,
Delphine