The Lap Seam is not quite as confusing as the Butt Seam, because as the term implies, it is lapped or overlapped at the seam.  The confusion comes with the amount of overlap of the top and bottom plies in relation to the left and right sides of the top and bottom coverstitch.  The standard design for this operation is to have the top ply not go completely to the left edge of the stitch, so that any loose threads that may appear at the trimmed edge would not have the possibility of sticking out beyond the stitch, therefore giving a smooth–looking finish on top.  The bottom ply however, would go fully to the right edge of the stitch because this would be on the inside of the product and would not be seen, Figure 8. The amount of overlap can vary slightly, but is not affected as much as the Butt Seam is by the type and weight of material being sewn. For the majority of the customers and operations, the standard amount of overlap is acceptable, because the seam has the added strength of being overlapped, yet still is smooth to the touch and has a flat appearance.  Recently some customers have been requesting to have a Full Lap Seam, where the top ply goes fully to the left edge of the seam, Figure 7, and in some cases the edge of the material actually sticks past the left edge of the stitch.  For those types of operations, the use of special presser foot shoes, cloth guide, lap former and presser foot are needed. In these cases the customer’s material, thread and sample products are required by our sewing engineers so that special sewing parts can be made.