To sew welt pockets on knits can be tricky due to the stretchy fabric. In this tutorial I show how you can achieve nice looking welt on soft knits.
Step 1. Interface the area that will be cut into a welt pocket. Make sure the piece cover the opening and then some
Step 2. Mark the welt pocket area using pins and pen. Put pins through the pattern piece in each corner and mark the points with a pen
Step 3. Using the corners as a guide, draw a rectangle
Step 4. Mark the lines
Step 5. Interface and fold the welt piece
Step 6. Machine baste the mid line
This will be a guide for the placing of the welt. Baste the welt piece along the seam line.
Step 7. Attach the welt piece
Step 8. Pin the larger (upper pocket piece) on the right side
Step 9. Attach the pocket piece by sewing a rectangle along the marked lines
Step 10. Cut the opening, doing the corners on the diagonal
Step 11. Push the pocket lining through so that it ends on the wrong side
Now the welt will visible.
Step 12. Attach the inner pocket piece to the upper piece
(sorry forgot to take a photo of that)
Step 13. Stitch across the ends to attach the welt to the pocket lining
Step 14. Flip the garment and top stitch the welt in place close to the sides
The finished result. I got some gaping but I think it is unavoidable when doing welt pockets in these kind of fabrics.