After 1931, as this is the last patent date on the envelope.
Here's another beautiful embroidered smock from the 1930s. See McCall 4531 for a somewhat earlier and simpler smock, and McCall 603 for a late '30s offering. A price of forty-five cents makes this a somewhat expensive pattern. At this period inexpensive DuBarry and Simplicity patterns were available for 15 cents, while an undecorated smock from Vogue was available for 25 cents.
This version, with its dropped shoulder line, standing collar (View A), and "primitive" geometric embroidery motifs seems to borrow from folk or regional dress. The shaped pockets unusual.
Recommended materials include linen, cotton, silk, and wool jersey. The recommendation for silk or wool jersey is interesting, as these fabrics would require some care in laundering, moving us away from a strictly utilitarian garment even without the extensive embroidery.
The embroidery is to be executed with tapestry wool or perle cotton. The colors recommended for View A are gold, black, and white; for View B, which is made up in "natural linen," coral, purple, and bright green are used; for View C pale green, orange, and dark blue. Note that the seams and hems are all embroidered - a lot of work!
This pattern has been cut with the exception of the tie belt. The transfers are unused. We saw this preservation of the transfers in McCall 603, so while the beautiful embroidery may have been a selling point, and the buyer paid a premium price for the pattern to get the transfers, not all makers had that much commitment to their projects.