Making adjustments to a muslin to improve a garment’s fit is an important part of my sewing process. But my work isn’t over after the fitting. I always transfer the changes to my paper pattern rather than use my muslin as a pattern. Mock-up fabric—be it muslin or other fabric—molds to the body to some degree, and doesn’t provide the precision I want. A paper pattern is stable and flat, and, therefore, is the best starting point for a garment that reflects your fitting changes. The expression I always hear in my mind is, “Paper doesn’t lie.”    

Transferring the changes accurately from the muslin to the pattern is a key part of this process. I’ll show you my technique for doing so. Some changes are as simple as altering a seamline; others may be more complex and involve one or more adjacent pattern pieces.…