Long-time followers of this blog know that it puzzles me when I watch a movie set in a certain year and see a lot of products used as background props how the set decorators knew that the products they showed were actually available in in the year when the story happened.

When I research the kinds of products that were in used during, say, the time-period of  “Little House on the Prairie” (which had a general store), I wonder how the film crew verified what products they could show and what products they couldn’t show. Many product availability dates are obscure, given in terms of decade rather than specific year.

If you’ve been around for a while, you may remember that Duz laundry detergent gave away one item of Golden Wheat dinnerware in each box. But what year did they start doing that? Most sites say the 1950s. Others, the late 1950s. Neither Proctor & Gamble (who made Duz) nor Homer Laughlin (the company that made the China) mention the promotion.

There are a few blogs out there discussing the China (which has become a collectable) and how much fun it was to find it in the soapboxes. They don’t mention when the promotion started either. Neither do sites showing vintage Duz ads. I remember these kinds of promotions from when I was a kid: cereals, gas stations, and almost everyone else seemed to be giving away stuff. But, it’s not like I kept a diary that noted what day we got our first free drinking glass from an AMOCO or Gulf service station.

I have a feeling this Duz promotion began after the year in which my novel-in-progress is set. Nonetheless, I want to know what year the promotion began so that I can confess in the author’s note that I fudged it a few years.

—Malcolm

Malcolm R. Campbell is the author of “The Sun Singer.”