For a continuous placket to function correctly, it must possess sufficient length to fold over itself. This ensures both edges of the placket opening are adequately reinforced and finished. The following steps outline the calculation:
1. Functional Necessity: The pattern piece must accommodate two layers of fabric that completely obscure the placket opening. Therefore, its length must be at least double the length of the opening.
2. Seam Allowance Consideration: Incorporating additional fabric for seam allowances is standard practice. This allows for superior finishing and compensates for minor inaccuracies in cutting or stitching. A typical addition for this purpose is 1 inch.
Calculation: Pattern Piece Length = (2 × Finished Placket Length) + 1 inch
Consequently, the correct measurement is: Double the finished placket length plus an additional 1 inch.