Occlusives are agents that form a thing film over the skin or hair which serves as an additional protective barrier.
Occlusive agents are effective against water loss, and are used as moisturizers.
Familiar occlusives are petrolatum (vaselin) and zinc oxide. But also silicones, different waxes (candelilla, carnauba, beeswax, wool wax or lanolin) and butters can act as such. Some emollient oils like jojoba, macadamia and castor as well as mineral oils can act as occlusive agents too.
Generally safe. Individual ingredients can cause a skin reaction. We recommend to apply them twice a week and increase the frequency if your skin is happy.