0vaseline petroleum jelly vaseline petroleum jelly is a mixture of mineral oils, paraffin and microcrystalline waxes that, when blended together, create something remarkable a smooth jelly that has a melting point just above body temperature. The result it literally melts into skin, flowing into the spaces between cells and the gaps in our lipid barrier. Once there, it re solidifies, locking itself in place. Vaseline petroleum jelly serves two functions first it helps keep the outside world out it protects skin from the effects of weather and exposure. Second, it acts like a sealant to help keep the inside world in it forms an occlusive barrier to the natural water loss of our skin. So skin that is dry and chapped is protected from drying elements, enabling skin softening moisture to build up naturally from inside the skin itself.