Rarely does a bride fit perfectly into an off-the-rack gown. Fortunately, bridal gowns are designed to be altered, with generous length and wide seam allowances. A skilled seamstress with some experience making formal dresses can alter most bridal gowns as well.
To fit the gown, insist that the bride wears the exact undergarments and shoes that she will wear with the gown. First pin the bodice, beginning at the waist. Long quilting pins are best to use, since they are strong enough to penetrate the multiple layers of a bridal gown. The weight of the gown should hang from the waistline, not from the shoulders or from the top edge. Once the waistline is pinned, finish pinning the sides. The top edge of a strapless gown should be snug enough to lie flat against the skin, but should not dig into the skin. If a dress has shoulders, pin the shoulders so that the armhole is comfortable. If the dress has sleeves, adjust the width, if needed, before marking any length adjustment. Continue pinning the sides from waist through hips, if the dress is fitted through the hip.
Mark the hem one layer at a time, beginning with the layer closest to the slip. Under layers should be about one and one-half inches from the floor all around. The outermost layer, the dress itself, should be one inch from the floor for safe walking. If the gown has a train, start tapering at the side seam until the hem blends with the train.
Once pinning is complete, begin sewing. For the bodice, transfer the pin marks to each layer of the bodice. Open the bodice as needed to provide access to the seams to be altered, using a razor blade or surgical-style seam ripper. Sew the outermost layer as marked and the lining slightly looser than marked, because the lining is already made slightly smaller than the dress itself. Remove the old seams and press the new seam allowances open, using a seam roll. Next alter the shoulders as marked, followed by the sleeves.
Hem layers one at a time. Support the weight of the dress on a large table and be sure all fabric is out of the way except the layer being hemmed. Layers of tulle (netting) are hemmed by cutting to the finished length with a steady hand and sharp shears. For other lining layers, press the crease for the hem, sew along the fold, trim excess fabric, then turn and stitch again to enclose raw edge. The outside layer should be hemmed like the original manufacturer’s hem, blending the new hemline into the train. Consult any bridal sewing book for specific instructions for different types of formal hems, such as horsehair braid or lace.