Why we bias-cut the Halsey slip
The Halsey slip started as a straight-grain sample, and it hung badly. Not obviously badly - it hung the way most slips hang, which is to say it fell in flat vertical lines and sat on the body rather than moving with it. Sienna kept it on the form for a week and then cut it apart.
Bias means cutting at 45 degrees to the weave, and it is expensive in two ways. It consumes roughly 30% more fabric per garment because the pattern pieces cannot be nested efficiently, and it demands a sewer who understands that bias-cut silk grows on the table overnight. We hang every cut panel for 24 hours before it is joined, so the fabric does its stretching before it reaches a seam rather than after it reaches a customer.
What you get for that is a garment that drapes around the body instead of over it. Madeleine Vionnet worked this out in the 1920s and the archive images are still the clearest argument for it we have found. Our sample room has three of them taped above the pattern table.
The Halsey costs more than it would on the straight grain and we sell fewer of them per yard of silk. It is still the piece customers write to us about most often, usually some version of the same sentence: it is the only slip I own that does not need anything under it.
