The Field Manual

Reference Guides

Six quick-reference tables that turn a single marker — a registration number, a union mark, a fibre, a seam — into a date range you can trust.

RN & Regulatory Numbers

RN, WPL, and CA numbers identify the company behind a label and set a firm earliest-possible production date.

The ILGWU and its successors redesigned their labels on a known schedule — wording and logo pinpoint the decade.

Care instructions moved from optional text to mandatory symbols, giving a high-resolution timeline for dating.

Synthetic fibres entered the market on specific dates — a fibre name can rule out an entire era.

Zipper makers and materials are stamped clues: metal Talon, plastic teeth, and YKK each mark a period.

Single vs double stitch, seam finishes, and collar construction reveal when and how a garment was made.