Buffers are usually of three types: Acidic buffers: They consist of a weak acid and its salt of a strong base. Th â¦ ey keep the pH constant in the acidic range.Basic buffers: They consist of a weak base and its salt of a strong acid.
I always go with SPF 50+. But, to be honest, there is not *that* much difference on a daily basis from SPF 25 to SPF 50: To figure out your level of protection, divide 1 by the SPF number.That equals the percentage of rays that are allowed to pass through. So SPF 25: 1/25 = 4% of rays pass through.SPF 50 = 1/50 = 2% of rays pass through. always go with SPF 50+. But, to be honest, there is not *that* much difference on a daily basis from SPF 25 to SPF 50: To figure out your level of protection, divide 1 by the SPF number.
It quantifies the amount of time you can be in the sun wearing sunscreen before you are burned. So if you are fair-skinned and would begin to burn in ten minutes without sun protection, wearing an SPF of 15 will protect you fifteen times as long - for 150 minutes (10 x 15 = 150). SPF math is also deceptive because the numbers don't add up. SPF 30 does not double the protection of SPF 15, for example. It would figure that you should be able to stay in the sun thirty times longer, but that's not the case. An SPF 15 allegedly blocks 93 to 95 percent of UVB rays, while an SPF 30 supplies 97 percent coverage.