Petroleum jelly comes from crude oil. It starts as a waxy residue that naturally builds up on oil drilling equipment, then goes through extensive refining to become the clear, semisolid product sitting in your medicine cabinet. Every jar traces back to the same source: the leftover material from oil and gas production.
How It Was Discovered
In 1865, a young chemist named Robert Chesebrough visited the oilfields of Titusville, Pennsylvania, where America’s first commercial oil wells were operating. Oil workers there had been dealing with a waxy buildup that kept clogging their wellheads and equipment. They considered it a nuisance, but Chesebrough noticed something else: the workers were smearing the stuff on their cuts and burns, claiming it helped them heal.
Chesebrough brought samples back to his laboratory in Brooklyn and spent years experimenting with the waxy substance. He eventually patented a method for refining it into a clean, consistent balm. He called the finished product “petroleum jelly,” a name that stuck and eventually became synonymous with the brand he built around it, Vaseline.
What It’s Actually Made Of
At the molecular level, petroleum jelly is a mixture of hydrocarbons, compounds built entirely from carbon and hydrogen atoms. Most of these hydrocarbon chains are 25 or more carbon atoms long, which is what makes the substance semisolid rather than liquid at room temperature. It melts between about 38 and 54°C (100 to 129°F), right around body temperature, which is why it softens so easily against your skin.
The texture comes from its unusual internal structure. Petroleum jelly is technically a colloidal system: tiny clusters of solid, branched hydrocarbon molecules trap high-boiling liquid hydrocarbons inside them, almost like a microscopic sponge. This is why it feels smooth and spreadable rather than crumbly like a candle wax. The solid framework holds the liquid component in place, giving petroleum jelly its characteristic slippery, occlusive quality.
From Oil Well to Pharmacy Shelf
Petroleum jelly is still produced the same fundamental way it was in Chesebrough’s era: as a byproduct of oil refining. When crude oil is processed, manufacturers collect the leftover petroleum material and subject it to additional purification steps. The goal is to strip away everything that isn’t the desired mix of semisolid hydrocarbons.
The raw material straight from a refinery contains impurities, including polycyclic aromatic hydrocarbons (PAHs), which are known carcinogens. Removing these compounds is the critical step that separates industrial-grade petrolatum from the pharmaceutical-grade product you’d put on your skin. The most effective method for eliminating PAHs is adsorption, a process where the raw material is passed through beds of activated carbon or clay that trap and pull out the problematic compounds. Other approaches like solvent extraction exist but tend to be less thorough.
The difference between grades matters. Industrial-grade petrolatum, used in machinery and manufacturing, undergoes less refining and can still contain traces of PAHs. The product labeled “USP” (United States Pharmacopeia) or “white petrolatum” meets strict pharmaceutical standards. USP-grade petroleum jelly must pass specific UV absorbance testing designed to detect even trace levels of carcinogenic PAHs. It also must leave virtually no residue when burned off at high temperatures, with a limit of no more than 0.05% remaining material. These standards exist precisely because the raw source material carries real risks if it isn’t properly cleaned up.
Why the “Petroleum” Part Concerns Some People
The name itself raises eyebrows. People reasonably wonder whether rubbing an oil industry byproduct on their skin is safe. The concern isn’t unfounded for poorly refined versions. The European Union has classified petrolatum as potentially carcinogenic unless the full refining history is known and shows it has been adequately purified.
For USP-grade white petrolatum sold in pharmacies, the refining process removes the compounds responsible for that risk. The finished product is one of the most widely used skin protectants in medicine, recommended by dermatologists for wound care, eczema, and preventing moisture loss. Its safety profile at the pharmaceutical grade has decades of clinical use behind it.
The practical takeaway: the grade and refining matter more than the source. A jar of Vaseline or any USP-labeled petroleum jelly has gone through purification specifically designed to eliminate the hazardous components present in crude oil. Bargain products without a USP designation, or petroleum jelly purchased outside regulated markets, may not have undergone the same level of refining.