What is the meaning of the SPF number in sunscreen?
The meaning of the SPF number in sunscreen has caused much confusion. SPF stands for Sun Protection Factor. The number afterwards comes from a formula. The formula is used to calculate the number of minutes your skin be safely exposed to the sun before it starts to have negative effects.
Think of it as a stop watch that starts when you step out into the sun. The higher the number, the more minutes it buys you.
Protection increases slightly as the SPF number goes higher by allowing less percentage of rays to hit your skin.
Do SPF 15 and 50 have the same ingredients?
SPF 50s will have more zinc. The higher the zinc the more protection, but also the whiter the cast that it leaves. In fact, you can buy a zinc stick, which is like a chapstick for areas where you’re highly exposed.
Keep in mind that sunscreens do not always protect you from burning. It will definitely extend the amount of time you can safely be in the sun before it starts causing damage. However, for some skin types will burn anyway with or without sunscreen.
Physical vs Chemical?
Physical sunscreens are made of minerals and act like sunglasses for your skin. zinc is a mineral is a finely ground rock that has been finely crushed that sits on the skin. When you apply it, it binds to your skin at the surface and provides a “shade” over your skin.
Physical sunscreen is the best type of sunscreen to use over your face or for sensitive skin types. On the other hand, they tend to be a little greasier because they do not absorb into the skin. Also, they can leave a white cast depending on how high your SPF is.
Chemical sunscreens absorb into the skin right away, they are not greasy and do not leave a white cast. however, they are actually going into your skin and interacting on a cellular level, coating each cell. While they have benefits, the fact that they are going into your cells leaves room for adverse reactions.
New day sunscreens
Some product lines have become more sophisticated with their formulations and are able to dilute the white cast without losing efficacy or adding ingredients.
Now that you know the meaning of the SPF number in sunscreen, which SPF is right for you?
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