As a supplier of fine vintage lingerie to film and TV studios, I know that costume designers will usually insist that the lovely items they purchase from me are, to the fraction of a decade, dated accurately and they ask me to prove it. So they should. Provenance and context in fashion history means everything to them, and me too. So, how can we tell when vintage clothes were made? A good personal knowledge of fashion history helps of course, along with a grasp of when certain brands and trademarks existed. But these things can only ever be approximate. It is possible to do a vintage clothing label search online, but they are often reliant on donated images and, who knows, the contributor could be too vague in their label dating efforts, or even wrong. One hugely useful and accurate method involves scanning through literally hundreds of vintage clothing ads in newspaper archives. Trust me, it is toe-curlingly tedious hard work and involves expensive subscriptions to archives but it is well worth the effort if one is to constantly add value to stock assets that may end up on a film set. Newspaper ads are fail-safe. They date an item not to a vague 'give-or-take-a-decade' but to an actual date on a calendar. That's super accurate. You can track the availability of a garment type throughout it's commercial lifespan by following trails left by vintage clothing ads. Some vintage clothing styles were produced and sold for well over a decade, but some were only in existence for a year or two before being discontinued and replaced. Without provenance in fashion history context, a vintage item will never truly come to life.