View Full Version : Spf.

07-10-2008, 05:06 AM
SPF - Sun protection factor.

do you know what it means?

some little known facts that i've gathered up:
SPF measures how long you can stay out in the sun. SPF 15 means you can stay out for 150 minutes before you turn red. BUT SPF 15 only protects about 93% of UVB rays, while SPF 30 protects 97%. its not proportional.

broad spectrum--what is it? it means it also protects against UVA aging rays.

so choose your sunscreen carefully!

07-10-2008, 01:42 PM
Hmm... I haven't thought about it that way. Every time I check out the SPF, I always look for the ones with the higher SPF value but I had no idea that it has to do with the amount of time you have to bask in the sun.

07-11-2008, 03:13 AM
yes, and higher SPF doesn't necessarily mean better protection, it just makes the chance of you not burning bigger--in the case that you don't reapply.

07-12-2008, 04:23 PM
What I don't get is the UVA and UVB thing. Is that just the different types of sun rays that are given off or is there more to it than that?

07-14-2008, 02:00 AM
UVA rays have longer wavelengths than UVB rays, which means they penetrate your skin deeper, causing wrinkles and loss of elasticity (collagen). UVB rays have shorter wavelengths, so they do not penetrate your skin as deep, and they cause the normal suburn that you see on the beach.

There is also a third kind of UV ray: UVC. But this doesn't get through the ozone layer (thank god).