An old advertisement can be a wonderful source: its layout, wording and chosen audience tell us how a product was presented. Trouble begins when the sales claim is repeated as though the advertisement also proves the product performed that way.
Copy the question before the claim
Ask what you want to learn. “How was this material marketed?” is a question an advertisement may help answer directly. “How did it perform after years of use?” requires different evidence.
Record the publication, date and page, then paraphrase the claim in your notes. Keep distinctive wording in short, clearly marked quotations when necessary. Do not quietly turn “promoted as durable” into “proved durable”.
Look at who was being addressed
A trade publication, household magazine and dealer catalogue may frame the same material differently. Examine the visible context rather than guessing an audience from the illustration alone. Price, layout and surrounding material can raise useful questions without settling them.
The Smithsonian’s DuPont Nylon Collection finding aid lists promotional publications alongside other kinds of records. It offers a practical reminder that marketing is one part of an archive, not a substitute for the whole documentary trail.
Choose a second kind of source
If you want to investigate a performance claim, look for a relevant test report and read its conditions. For evidence of use, a dated photograph or personal account may help, but each has its own limits. Two advertisements repeating the same claim are not automatically independent confirmation.
Finish with a sentence proportional to what you found: “This advertisement presented the product in these terms.” You can then explain what remains unverified. Our guide to following a paper trail helps connect those sources without asking any single document to tell the entire story.