How to attach a lined patch pocket flap
Start by marking the location of the flap above the patch pocket. You can measure and mark this line with tailor chalk or a basting stitch as shown above. This line will correspond to the finished edge of the flap. In this tutorial, the flap is positioned 1” above the pocket opening edge- this distance is measured with a ruler or gage pointer.
To attach the lined patch pocket, it is important to leave about 1/2” unstitched at each end of the top horizontal edge (the edge being stitched to the garment surface)
2. Align the flap face side down such that the seamline along the unfinished horizontal edge aligns with the basting stitch applied in step 1. It helps to mark the seamline directly on the wrong side of the flap using tailors chalk or a quilting pencil as shown above. Insert pins or hand baste the pocket flap in this position. Hand basting is highly recommended as it it will keep the flap layers accurately secured in position without the risk of shifting in the machine stitching process below. Hand baste within the seam allowance.
Machine stitch the flap to the garment layer underneath following the seamline as a guide - this stitch should correspond to the hand basting applied in Step 1. Back stitch at the beginning and end of the stitch for extra strength and stability. Remove the hand basting once the stitch is applied.
Lift the lining seam allowance layer and fold the two lining corners inward as shown.
Next, fold the lining seam allowance halfway to encase its raw edge as shown above.
Trim the self seam allowance layer down to about 1/4”. This seam allowance layer is located underneath the lining layer.
Trim the corners of the self seam allowance diagonally so they can be hidden underneath the lining seam allowance on top.
Bring the folded lining seam allowance down to encase all raw edges and hand baste the seam allowance layers in this position to secure.
Starting on one end of the seam allowance, topstitch down along the the folded edge, then pivot the stitch horizontally to stitch then back up again along the other end, to complete the stitched seam allowance and encase all raw edges underneath.
Remove the hand basting using a seam ripper once the flap seam allowance is fully topstitched and all raw edges are securely enclosed.
Fold the flap down in its natural position and iron the flap's folded edge in this position.
You will most likely find that ironing alone is not quite enough to keep the flap down. To ensure the flap is permanently directed downward, topstitch each end/corner of the flap layer to secure it in this position.