Marc vom Ende is a senior perfumer at German fragrance house Symrise, and he started working on nailing down the scent of paper U.S. currency when artist Mike Bouchet commissioned the search two years ago. Vom Ende said the aroma has a base of cotton, ink and soap—with notes of metallic cashiers, leather wallets and less pleasant substances, the Wall Street Journal reports.
“Money takes something from everyone who uses it,” vom Ende said. “That makes it crazy complex, but that also makes it interesting to detect.”
Vom Ende first stuck new and used U.S. bills in an airtight container with charcoal, which absorbed the scent so he could analyze it. The scent's ingredients he found were mostly aliphatic aldehydes, which are prevalent in soap or linen, and alkanes, which are found in ink, in addition to plenty of "animal-derived" compounds found in body oils or secretions (the Journal adds he found "more" evidence of fecal matter than he expected).
It took six months to pinpoint the smell of new money, and another eight to nail down the used type of bills. The Journal reports that while counterfeiters may be interested in adding authenticity to their bills with vom Ende's results, experts do not use smell to determine whether money is real or fake.