Zinc sunscreen is a type of sunblock that contains zinc oxide in some amount. This ingredient will usually be listed as micro or micronized zinc oxide. Sunscreens that have a minimum of 5% zinc oxide listed on the package generally offer the best protection from the sun's harmful rays. It is also important to choose a zinc sunscreen that will work with your activities and your skin type. For example, it will be best to choose a water-resistant brand if you will be swimming or sweating a great deal to make sure that your skin is protected even when wet.
The UV rays that sunscreens protect against are ultraviolet rays that reach Earth from the sun. This is a type of radiation that can be separated into UVA and UVB rays. Both types of rays penetrate the skin when sunscreen is not used, and both contribute to issues such as premature aging, wrinkling, eye damage and a heightened risk of skin cancer. Sunscreens are designed to block these rays from absorbing into the skin and affecting the cells with their radiation. Formulas that do not contain zinc oxide may fully protect against UVB rays, but will generally let at least some of the damaging UVA rays through.
There are many different brands of zinc sunscreen on the market today, all with varying numbers for what is known as the Sun Protection Factor (SPF). Your ability to stay in the sun without burning is lengthened by the SPF number. A zinc sunscreen that has an SPF of 20, for instance, means that you can be exposed to the sun 20 times longer than you could without wearing the sunscreen before you are at risk for a sunburn. For this to be accurate, the sunscreen would need to be reapplied at the intervals recommended by the manufacturer. Unless the sunscreen states that it is water-resistant, it may also be necessary to apply it more frequently if you plan to swim or if you sweat very much.
The SPF number only refers to how long the sunscreen can block the sun's UVB rays, which are most powerful during the peak hours of the day during the summer season. These are the rays that typically cause sunburn. UVA rays are those that are constantly present when there is sunshine, and that generally penetrate the skin more deeply to do more damage over time. The type of zinc sunscreen you use should be one that states it can block all of the UVA and UVB rays.
Zinc sunscreens may remain visible after they are applied to the skin. Some people use a sunscreen for face protection that is pure zinc oxide, which leaves a thick, white substance on their skin. This offers the best UVA and UVB protection possible, which also means it is unlikely the person will get even a mild suntan while wearing it. People with highly sensitive skin who are irritated by most sunscreens may be able to wear pure zinc oxide with no negative reactions.