A sloper is a pattern of your figure; it's a great tool for adjusting commercial patterns. By directly comparing the sloper to a style pattern, you can make initial alterations that eliminate many fit problems at the pattern stage. To begin, you will need a properly fitted sloper or moulage copied onto a clear plastic sheet. This transparent pattern functions as a reference guide, so you can change the commercial pattern as needed to reflect your figure's dimensions, proportions, and shape.
You will then sew and try on a muslin test garment and tweak any remaining fit issues. Transfer these changes to the pattern, and you are ready to move to the fashion fabric.
This may seem like a lot of work, but once you grasp the process, you'll be able to adjust patterns in many styles confidently and efficiently. As a result, you'll spend less time overall in fitting, and more time sewing—and wearing—flattering, fashionable garments.
Prepare the sloper and pattern
SLOPER VS. MOULAGE
A moulage and a sloper are custom-fit patterns that can be used as the basis for new garment designs. A moulage fits like a second skin, with no added wearing or design ease. It's useful for working with knit patterns or for tightly fitted bodices, such as those on evening gowns.
A sloper has some ease—1 inch to 3 inches, typically—for comfort rather than style. For any garment pattern with normal wearing ease, such as dresses, blouses, and tops, the sloper works well. Eventually, you may want to create a jacket and overcoat sloper,
with layering ease included.
To learn to drape
TRACE THE SLOPER
Trace your sloper or moulage onto a sheet of clear plastic. I recommend smooth/matte polypropylene sheets, 24 ½ inches by 45 inches by .02 inches, from TapPlastics.com. This material lies flat on the paper pattern without clinging. Avoid inexpensive vinyl sold on rolls; it's too sticky. Duplicate your sloper on the plastic with a black permanent marker, including all key markings (bust apex, waistline, hip, and darts).
MARK THE PATTERN
Many commercial patterns are multisized. I recommend marking the stitching lines on the pattern tissue for your desired size. Alternatively, you can trace a copy for a clearer view of the stitching lines. Prepare the main body pieces only; facings, collars, and other design features will be adjusted after completing the basic fitting process.