White petrolatum has been protecting human skin since the 1870s, and a century and a half later, nothing has beaten it. It remains the most occlusive single ingredient in skin care, the benchmark every newer barrier technology is measured against, and the quiet workhorse behind ointments trusted in hospitals, nurseries, and hundred-mile races alike.
That is exactly why it is the foundation of our ultra-distance formula, and exactly why it is not in our marathon one. Maximum occlusion is a tool for the extremes.
The Science of Petrolatum
The landmark research on petrolatum was published in the Journal of the American Academy of Dermatology: petrolatum reduces transepidermal water loss by roughly 98%, more than any other single ingredient tested, while remaining permeable enough to allow barrier recovery underneath[1]. Rather than forming an inert plastic film, it penetrates the upper layers of the stratum corneum and fills the spaces between corneocytes, which is why it stays put under conditions that shear lighter films away.
For an ultra runner, that translates to three properties no natural butter matches: near-total water resistance through hours of sweat, chemical inertness that makes irritation and allergy essentially unheard of, and persistence under sustained friction. Skin tribology research confirms that moisture at the skin-textile interface is the main multiplier of friction damage[2]; the most occlusive barrier available is the bluntest possible answer to it.
Petrolatum's weaknesses are feel and structure: alone it is heavy, and it softens in heat. In our formula those jobs are handled by soy sterols and a microcrystalline-paraffin wax system, so the barrier performs at full strength without wearing like a jar of petroleum jelly.
White Petrolatum at a Glance
| INCI name | Petrolatum |
| Source | Highly refined petroleum derivative (USP grade) |
| Type | Occlusive barrier |
| Occlusion | Reduces water loss by ~98%, the highest of any single ingredient[1] |
| Primary role | Maximum-strength friction and moisture barrier for extreme conditions |
| Found in | Aura Ultra (foundation) |
Inside the Aura System
White petrolatum is the foundation of Aura Ultra, built for 50K to 100+ mile races, desert heat, and alpine cold, reinforced with lanolin and structured with waxes. It is deliberately absent from Aura Full, which keeps a natural-inspired list for marathon distance and daily training. Two formulas, two jobs, honestly labeled.
For the Long Distance Runner
As makers of elite anti-chafe balm for long distance runners, we chose petrolatum for the one scenario where nothing else survives: the far side of an ultra. Past 50K, sweat exposure is measured in half-days, aid stations may be hours apart, and the difference between a 98% occlusive barrier and an 80% one compounds with every mile. The research that documents petrolatum's unmatched water-loss reduction is, in practical terms, a description of why it is still on your skin at mile 80.
For the marathon and the daily training block, that much occlusion is more than the job requires, which is why our natural formula covers those miles instead. Elite protection means matching the barrier to the distance, not maximizing it everywhere.
Frequently Asked Questions
Is petrolatum the same as Vaseline?
Vaseline is a brand of pure petrolatum. Aura Ultra uses the same ingredient class at USP grade, but combines it with lanolin, structuring waxes, and soy sterols so it holds texture across temperature extremes and feels less heavy than plain petroleum jelly.
Is petrolatum safe for skin?
Cosmetic-grade white petrolatum is highly refined and among the least reactive ingredients in all of skin care, which is why it is the standard base for products used on compromised and post-procedure skin. Concerns about impurities apply to unrefined petrolatum, not the USP grade used in skin care.
Why do ultra runners use petrolatum-based products instead of natural balms?
Duration and conditions. Natural oil-and-butter balms soften in desert heat, harden in alpine cold, and wash off under hours of sweat. Petrolatum holds its barrier through all three, which matters most when the next aid station is hours away and reapplication is not guaranteed.
References
- Ghadially R, Halkier-Sorensen L, Elias PM (1992). Effects of petrolatum on stratum corneum structure and function. Journal of the American Academy of Dermatology, 26(3), 387-396.
- Gerhardt LC, Strässle V, Lenz A, Spencer ND, Derler S (2008). Influence of epidermal hydration on the friction of human skin against textiles. Journal of the Royal Society Interface, 5(28), 1317-1328. https://doi.org/10.1098/rsif.2008.0034
