​Finish Facings Edges Before Attaching Them To The Garment

When clean finishing a garment wedge with a facing, the facing compartment is first stitched then attached to the garment edge it finishes. The inner, shorter edge is always stitched to the garment's raw edge, while the outer, usually longer edge, corresponding to the inside of the garment and should layer flat agains its surface. 

Before sewing the facing layer to the garment, but after the its seams have been stitched and ironed flat, it it helpful to clean finish the facing's outer edge using the technique of your choice. The edge finishing technique you choose should not add bulk, tension and excess thickness to the finished garment. 

Encasing this raw edge with an overedge stitch like serging or zigzag on your home sewing machine, is the simplest, fastest and most effective way to clean finish facing edges. In addition, this technique keep the finished edge smooth and flat without adding any unnecessary bulk and thickness. ​

The reason why it is best to clean finish an outer facing edge prior to attaching the facing to the garment, is that it is simply easier to handle this edge alone without having to deal with the rest of the garment during this process.