This is a method for sewing a double layered sleeveless dress or top in such a way that all seam allowances are enclosed within the two layers. This could be used to create entirely reversible garments as well as simply giving a nice and neat inner appearance. It is also useful when using sheer fabrics like mesh and very fine translucent knits to make a self-lined garment.
Cut the front and the back pieces with a 4cm hem allowance, and cut a front lining and a back lining, identical except with a 1cm hem allowance each. This will give a garment with a folded lower edge and the lower hem seam hidden inside 3cm from the fold. If a different hem allowance is desired then cut accordingly; or if the joining seam is desired to be right on the lower edge of the garment then cut the linings to be the same length as the front and back pieces.
(This particular top pictured has a straight folded edge at the upper neckline; but the method is just the same as if the linings were separate pieces that needed joining all round, since that neckline seam is the very first to be sewn… )
Pin the back to the back lining along the neckline edge right sides together, and stitch. Trim stitched seam allowances, turn right sides out and press flat.
Pin the front to the front facing around the neckline right sides together in the same manner, and stitch. Now for the front only! also pin the armhole edges of the front to the front lining and stitch. Leave the shoulder seam open and unstitched. Trim stitched seam allowances, turn right side out and press.
Open the back/back lining piece at the shoulder and wrap it around the front/front lining at the shoulder edge, all right sides together, back piece to front piece, and back lining piece to front lining piece, aligning the neckline seams. Pin all four layers together, ensuring the front neckline edge is abutted hard up against the neckline edge of the back/back lining. At the outer shoulder edge continue pinning the back to the back lining down the armhole edge, keeping the front free.
Stitch the shoulder seam, pivot at the outer shoulder edge, and continue stitching the armhole edge of back to back lining. Trim seam allowances, and pull the front piece out and through, turning the back/back lining piece right sides out and press flat.
Now open out the pieces; and pin the front to the back and the front lining to the back lining along the side edges; aligning the underarm seam exactly. Stitch side seams in one long seam; from lower hem to lower hem. Press seam allowances open.
Lay the outer layer over the inner layer wrong sides together aligning the side seams together and press again.
Separate the outer layer from the inner layer again and pin the lower edges of the outer to inner layers, right sides together and aligning the side seams. Stitch, leaving a gap of around 12-15cm, or big enough to stuff your garment through without stretching out the fabric too much. Use something long, skinny and padded to press the seam allowance down; I know there are proper thingies for the job but I generally use something like a rolled-up flannel.
Turn the garment back right side out through the gap left in the lower hem.
Inside the garment, press down the seam allowance of the outer layer to close the gap in the hem and pin in place. Slip-stitch the gap closed invisibly by hand, being careful to keep the outer layer free.
Voila! There are absolutely no seam allowances showing; anywhere!
