The Bunka Bodice Sloper constitutes a method of drafting established by the Bunka Fashion College in Japan and has been popularized by pattern books such as Tomoko Nakamichi’s Pattern Magic series and Yoshiko Tsukiori’s Stylish Dress Book(s), which have been made available in English in recent years. The Bunka method is a preferred method of drafting because it only uses a few measurements to generate a flat bodice block (a base bodice pattern that only accommodates the space of the body with little or no ease). These are center back length, waist, and bust. In reality, the pattern is primarily generated from the latter input, where back length and waist are only used once in the drafting sequence. All other measurements are proportions of the bust measurement. For instance, the front neckline depth is expressed as (B/24) + 3.4 cm. For this reason, the sloper is designed with a range of bust sizes and body proportions in mind: those of young Japanese women. The Pattern Magic books, for example, only include extrapolated measurements for bust sizes of 74 to 89 cm (for comparison, an American standard Misses size 8 is based on a bust measurement of 34 inches or 86 cm). Here, the body-specific is not only inscribed on the resultant pattern, a near-exact replication of the space of a particular body, but is embedded in the process itself. This is particularly interesting for a process of drafting which is ostensibly meant to account for the size and shape of an(y) individual body.
This exercise replicates the sequential process of drafting the bodice sloper in the space of a grasshopper script. Because the script is essentially contingent on one parameter, one can quickly produce patterns from a variety of bust measurements, particularly those that fall outside of the range of suitable measurements/bodies.
click the image for hi-res
Note the series of inputs contingent on the bust parameter.
And here are three bodices produced from bust sizes beyond the typical range.
The blue line indicates a cut (without seam allowance) and pink indicates a dart.
And finally, a material prototype, fabricated at half-scale in mylar:
This initial study seems to have elucidated a process of making that can be synthesized by three general steps:
Future study will follow from, expand and collapse this model, by interrogating linkages between drafting and representation, representation and making, and how material prototypes/methods of fabrication inform both systems of drawing (in this case, the script) and representation for making (the pattern/fabrication instructions).