Petrolatum

Petrolatum (CAS 8009-03-8) — also known as petroleum jelly or white petrolatum — is a semi-solid mixture of hydrocarbons with a melting point typically between 37–54°C. It is a well-refined petroleum derivative, distinct from unrefined petroleum-based products.

In lubricant formulations, petrolatum serves as a film-forming agent: it creates a thick, moisture-resistant coating on metal surfaces that helps prevent corrosion and retains lubrication under low-load conditions. Its waxy consistency means it leaves a more persistent, slightly tacky residue compared to purely oil-based carriers — useful for long-term protection on hinges and hardware, but prone to attracting grit in high-contamination environments.

In automotive multi-purpose lubricants, petrolatum extends the life of the applied lubricant film by slowing evaporation and migration. This same property is why petrolatum-containing lubricants are sometimes noted for attracting dust more readily than dry-film alternatives.

The pharmaceutical and cosmetic grade (USP white petrolatum) used in skin care products is the same basic compound as the industrial grade, processed to a higher purity standard.