Petrolatum

Petrolatum is the waxy, semi-solid fraction left when paraffinic residual oil is dewaxed. It is not one compound but a blend of saturated hydrocarbons, most of them longer than twenty-five carbons, with no fixed melting point and no single formula.^[1]

It is also the most single-minded material in the emollient cupboard. Petrolatum does one thing, and does it without taking part in any chemistry: it sits on the surface and slows the water leaving.

Distilling crude oil leaves a residue. Dewaxing that residue yields a mixture of crystalline and liquid hydrocarbons which, at room temperature, behaves as a soft translucent solid; the chain lengths run predominantly above twenty-five carbons, with no upper bound given in the registry description.^[2]

Nothing in the mixture is reactive. There are no ester links to hydrolyse and no unsaturation to oxidise, which is why petrolatum keeps almost indefinitely and never goes rancid. Grade matters more than chemistry here. White petrolatum is the more thoroughly refined and decolourised form — the United States lists the two separately as drug actives — and the degree of refining is the whole regulatory question.^[3]

Petrolatum reached the market as a refinery by-product turned into a product. Robert Chesebrough's process, as his patent sets it out, begins with the residuum left after the lighter fractions of petroleum have been distilled off: that residuum is distilled again under a vacuum and the result filtered through bone-black.^[4]

He was granted US Patent 127,568, Improvement in Products from Petroleum, on 4 June 1872. The patent text records that he had invented a new and useful product from petroleum which, it says, he had named Vaseline.^[4]

The founding anecdote usually told alongside it — that Chesebrough took the idea from the rod wax that gummed up pump rods on the Pennsylvania oilfields — is repeated everywhere and rests on later retellings rather than on the patent, so this entry does not assert it.

Petrolatum is an occlusive. Spread on skin it forms a continuous hydrophobic film that slows transepidermal water loss, and whatever then accumulates beneath the film is the skin's own water.

In makeup it is structural as much as conditioning. It gives body to anhydrous sticks and balms, holds pigment in a cream, and supplies the wet-looking gloss a pure wax base cannot. United States regulation treats it as a drug substance in its own right: 21 CFR 347.10 lists petrolatum, and white petrolatum separately, as over-the-counter skin protectant active ingredients at 30 to 100 per cent.^[5]

Petrolatum is restricted rather than freely permitted in the European Union, and the restriction is about refining rather than about petrolatum as such. As of September 2026, Annex II of Regulation (EC) No 1223/2009 — the EU list of substances prohibited in cosmetic products — prohibits petrolatum, entered under CAS 8009-03-8 and EC 232-373-2, unless the full refining history is known and it can be shown that the substance from which it is produced is not a carcinogen.^[6]

That condition is not a peculiarity of the cosmetics annex. Annex VI of Regulation (EC) No 1272/2008 on classification, labelling and packaging gives petrolatum a harmonised classification as a category 1B carcinogen under index number 649-254-00-X, and attaches Note N, which disapplies the classification where the full refining history is known and the feedstock is shown not to be a carcinogen.^[7] The test in both instruments is documentary. What has to be demonstrated is the refining history of the particular material, not a property of petrolatum in the abstract.

In the United States the same material is an approved over-the-counter skin protectant active.^[8] The two jurisdictions are answering different questions, and neither answer is a statement about any individual product.