Most of us know Vaseline as a go-to moisturizer, but its origin story is surprisingly unusual—and a bit extreme.

Invented in 1872 by Robert Chesebrough, Vaseline didn’t start as a skincare idea. Chesebrough once ran a sperm whale oil business, but after the industry collapsed, he turned to the booming oil fields of Pennsylvania for a new opportunity. There, he saw oil workers using a greasy residue from drill rods to heal cuts and burns.

Fascinated, Chesebrough spent 10 years refining the substance into a usable jelly, eventually trademarking it as “Vaseline.” But sales were slow—until he took drastic steps. Traveling with a cart, he burned his own skin just to prove how effective his product was. “Before long, he was selling a jar a minute,” comedian Sandi Toksvig shared in a BBC clip that has now gone viral.

Today, Vaseline is used to heal cuts, soothe dry skin, and even treat nappy rash. But few know it started as drill rod gunk—and with a very determined inventor lighting his own skin on fire to sell it.