The ABCs of Sunscreens - notes

jiang08UID: 2391146

Some basic rules to start with:
1, There are three types of sunscreens: chemical, physical, and combination
2, A good sunscreen should block both UVA and UVB rays.
3, UVA Rays:320 to 400 nanometers, could lead to  wrinkles and sunspot; present with relatively equal intensity during all daylight hours throughout the year, and can penetrate clouds and glass.
   UVB Rays: 290 to 320 nanometers, cause common surface sunburns; varies by season, location and time of day

----> From 3, we know that to prevent sunspots, we should always wear a sunblock that blocks UVA rays even on days without direct sunshine or during winter times.
----------> Now the question is, what are the ingredients that block both UVA and UVB rays?

4, Physical sunblock ingredients: titanium dioxide and zinc oxide (the only two)
    Chemical sunblock common ingredients: Oxybenzone, avobenzone, Mexoryl SX and Tinosorb
5, Oxybenzone can protect against only a portion of UVA rays (in the lower end of the spectrum); together with avobenzone, zinc oxide, titanium dioxide or Mexoryl SX, most UVA rays can be blocked.
6, Mexoryl SX is initially a a trademark of L'Oreal, protects against UVA rays well.
7, Paula Begoun claims that titanium dioxide and zinc oxide provide greater levels of protection than Mexoryl S.
8, Nano-sized titanium dioxide and zinc oxide will not leave a noticeable white cast on the skin.

------>Now it seems like combination sunscreens might be the best to cover broad spectrum


*********Measurements of sunscreen protection:****
1, SPF: for UVB rays. SPF 30 sunscreen does NOT offer double the protection of an SPF 15. SPF 15 blocks 93 percent of rays, while SPF 30 blocks 97 percent.
2, Persistent pigment darkening (PPD): for UVA rays. Originated in Japan. (What's the difference between PPD and PA??)

jiang08UID: 2391146

FDA facts:

source: http://en.wikipedia.org/wiki/Sun ... s_of_UVA_protection

FDA site


                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

FDA-Approved Sunscreens
Active Ingredient/UV Filter Name	Range Covered
UVA1: 340-400 nm
UVA2: 320-340 nm
UVB: 290-320 nm
Chemical/organic absorbers:
Aminobenzoic acid (PABA)	UVB
Avobenzone	UVA1
Cinoxate	UVB
Dioxybenzone	UVB, UVA2
Ecamsule (Mexoryl SX)	UVA2
Ensulizole (Phenylbenzimiazole Sulfonic Acid)	UVB
Homosalate	UVB
Meradimate (Menthyl Anthranilate)	UVA2
Octocrylene	UVB
Octinoxate (Octyl Methoxycinnamate)	UVB
Octisalate ( Octyl Salicylate)	UVB
Oxybenzone	UVB, UVA2
Padimate O	UVB
Sulisobenzone	UVB, UVA2
Trolamine Salicylate	UVB
Titanium Dioxide	UVB, UVA2
Zinc Oxide	UVB,UVA2, UVA1

From this chart: we see Zinc Oxide itself offers broad protection

jiang08UID: 2391146

some example products:

1, Shiseido Ultimate Sun Protection Cream For Face SPF 55 PA+++

Ingredients:
Octinoxate 7.4%, Titanium Dioxide 2.2%, and Zinc Oxide 16.3%

It absolutely offers maximum protection against UVA and UVB rays.

to be continued...

RayTongUID: 2325885

好锻炼英语阅读啊啊啊:mad:

shuroUID: 2401325

哇咔咔，等看

shuroUID: 2401325

没懂PPD是啥
哦对了08你草的那个防晒好像又有了嘛

jiang08UID: 2391146

没懂PPD是啥
哦对了08你草的那个防晒好像又有了嘛
shuro 发表于 2011-4-30 04:26

I didn't read through that part very carefully.
cuz PPD is only used in Europe and its hard to get in the U.S...

I see it's back in stock, but now i'm more inclined toward ZnO+some chemical ingredients

hischildUID: 2143480

为神马大家都还没有收到章子啊？？？

我周一就发信给草木了。。。

GuessyUID: 2184792

我有那个资生堂的温柔版 不过懒得涂

jiang08UID: 2391146

我有那个资生堂的温柔版 不过懒得涂
Guessy 发表于 2011-4-30 09:06

防晒不能偷懒的哇猜猜
UVA造成衰老很快的，色斑，皱纹都会提前出来…………
参考：酸奶的皮肤（几乎完美……）

shuroUID: 2401325

我也很懒，不怎么涂
只有出门前是大太阳才想得起来
虽然知道这些理论╮(╯_╰)╭

yangzexinUID: 2488312

男的就是方便

cmykelly0913UID: 2642754

>.<
女生好辛苦

dearmonetUID: 2616341

防晒不能偷懒的哇猜猜
UVA造成衰老很快的，色斑，皱纹都会提前出来…………
参考：酸奶的皮肤（几乎完美……）
jiang08 发表于 2011-4-30 09:10

嗯嗯，我可以证明，今天见到酸奶了，真是又白又嫩啊，感觉没什么毛孔，要坚持涂防晒啊！

Julia服部UID: 2624610

求3奶PP
打滚求