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DETAIL
Physical properties
Petroleum jelly is a mixture of hydrocarbons, with a melting point that depends on the exact proportions. The melting point is typically between 40 and 70 °C (105 and 160 °F). It is flammable only when heated to liquid; then the fumes will light, not the liquid itself, so a wick material is needed to ignite petroleum jelly. It is colorless (or of a pale yellow color when not highly distilled), translucent, and devoid of taste and smell when pure. It does not oxidize on exposure to the air and is not readily acted on by chemical reagents. It is insoluble in water. It is soluble in dichloromethane, chloroform, benzene, diethyl ether, carbon disulfide and turpentine. Petroleum jelly is slightly soluble in alcohol. It acts as a plasticizer on polypropylene (PP), but is compatible with most other plastics[citation needed]. It is a semi-solid, in that it holds its shape indefinitely like a solid, but it can be forced to take the shape of its container without breaking apart, like a liquid, though it does not flow on its own.
Depending on the specific application of petroleum jelly, it may be USP, B.P., or Ph. Eur. grade. This pertains to the processing and handling of the petroleum jelly so it is suitable for medicinal and personal-care applications.
Uses
Most uses of petroleum jelly exploit its lubricating and coating properties, including use on dry lips and dry skin. Below are some examples of the uses of petroleum jelly.
Skin and hair care
Most petroleum jelly today is used as an ingredient in skin lotions and cosmetics, providing various types of skin care and protection by minimizing friction or reducing moisture loss, or by functioning as a grooming aid (e.g., pomade). It's also used for treating dry scalp and dandruff.
Preventing moisture loss
By reducing moisture loss, petroleum jelly can prevent chapped hands and lips, and soften nail cuticles.
This property is exploited to provide heat insulation: petroleum jelly can be used to keep swimmers warm in water when training, or during channel crossings or long ocean swims. It can prevent chilling of the face due to evaporation of skin moisture during cold weather outdoor sports.
Hair grooming
In the first part of the twentieth century, petroleum jelly, either pure or as an ingredient, was also popular as a hair pomade. When used in a 50/50 mixture with pure beeswax, it makes an effective moustache wax.
Skin lubrication
Petroleum jelly can be used to reduce the friction between skin and clothing during various sport activities, for example to prevent chafing of the seat region of cyclists, or the nipples of long distance runners wearing loose T-shirts, and is commonly used in the groin area of wrestle