Petrolatum is a semisolid mixture of water insoluble hydrocarbons of high molecular weights. These alkanes are extracted from oil during oil refining processes. In the pharmaceutical industry, petrolatum is used as an oleaginous base and is used alone, or in combination with another ingredient(such as yellow wax) as an ointment base for semisolid preparations, usually to form water-in-oil emulsions. Only small amounts of water soluble substances can be incorporated into these bases and solid substances can be incorporating using a levigating agent. Substances with similar chemical characteristics can be incorporated in a larger volume. These bases can be difficult to wash off with water, can remain on the skin for long periods of time, and can protect and soften the skin. Regular vaseline (yellow petrolatum) is a yellowish/amber color and has a melting point between 30-60 degrees celsius. White petrolatum contains the same chemical components as yellow petrolatum but it has been decolorized in order to give it a more attractive appearance. Other uses of petrolatum include rust prevention, lubrication, skin protectant, moisture loss prevention(for chapped lips or dry skin), and other protectant and water repellant uses.


Sources:

1. Allen, Loyd V., and Howard C. Ansel. Ansel's Pharmaceutical Dosage Forms and Drug Delivery Systems (10th Edition). Baltimore, MD: Wolters Kluwer Health, 2014. Print.

2. "Petrolatum (white)". inchem.org. International Programme on Chemical Safety and the Commission of the European Communities. March 2002. Retrieved August 5, 2011.