How does sunscreen work?

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Offline Keola

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How does sunscreen work?
« on: 24/05/2009 17:59:25 »
I've allways wondered how sunscreen protect you? I'm guessing it "takes the hit" for your skin somehow, but how does it actually work?

Also is it true you can use lower protections once you've started to get a tan? The general idea beeing your skin is somehow "stronger" or more well protected on it's own when it's been exposed to the sun for a while.... ? [???]

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Offline lightarrow

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How does sunscreen work?
« Reply #1 on: 24/05/2009 20:05:10 »
I've allways wondered how sunscreen protect you? I'm guessing it "takes the hit" for your skin somehow, but how does it actually work?
Essentially, a sunscreen reflects off UV radiation.
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Also is it true you can use lower protections once you've started to get a tan? The general idea beeing your skin is somehow "stronger" or more well protected on it's own when it's been exposed to the sun for a while.... ? [???]
Yes, the dark pigments of the tun absorb the UV radiation preventing it to penetrate the skin.

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Offline Bored chemist

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How does sunscreen work?
« Reply #2 on: 24/05/2009 20:46:37 »
Most sunscreens absorb UV rather than reflecting it. The enegery is degraded to heat.
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Offline Karsten

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How does sunscreen work?
« Reply #3 on: 25/05/2009 01:30:50 »
Most sunscreens absorb UV rather than reflecting it. The enegery is degraded to heat.
That is interesting. Would that mean I am getting hotter if I put on this kind of sun screen? In a noticeable way?
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Offline lightarrow

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How does sunscreen work?
« Reply #4 on: 25/05/2009 08:24:47 »
Most sunscreens absorb UV rather than reflecting it. The enegery is degraded to heat.
Some internet pages explains as you do, some in the opposite, for example this one:
http://chemistry.about.com/od/howthingsworkfaqs/f/sunscreen.htm

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Offline Bored chemist

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How does sunscreen work?
« Reply #5 on: 25/05/2009 10:01:59 »
Most sunscreens absorb UV rather than reflecting it. The enegery is degraded to heat.
That is interesting. Would that mean I am getting hotter if I put on this kind of sun screen? In a noticeable way?

Not noticably. Without the sunscreen the UV would be absorbed by your skin and largely converted to heat anyway.

Also there's a difference between sunblock which is generally white and reflects the UV; and suncscreen which isn't and doesn't
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