Lazy post here, copy-pasted over from MakeupAlley…
Questions (edited from original):
1. Does anyone know of a good cheap d/s ss? *for the body** that has a high spf and really protects from the sun?
2. Also, what’s the difference between sunscreen and sunblock, I heard that sunblock blocks both UVA+UVB rays where sunscreen absorbs them? That’s bad isn’t it? Which one is better in blocking the suns rays?
1. was easy: Blue Lizard sensitive or baby spf 30
2. same thing: the term “sunblock” has been out of use in many places for a long time now (ex. EU). In the US, it’s one of the things that’s finally got round to being regulated by the FDA, though the guidelines have been delayed (December 2012). For more on that FDA regulatory business, do a board search on here.
Reasoning behind it: all a sun protecting substance can do is protect you from a high %age of solar radiation (most do this in the regon of 90-95%), but the curve mapping protection to SPF flattens off and never gets to 100% shielding. Hence “sunscreen” is a better term, as it will screen you from sun, just like those folding screens you’d use in a room, reducing light penetration. And “sunblock” is not a good word, as the stuff can’t actually “block” 100% of light & UV radiation.
It sounds to me like you’ve got your terms crossed over slightly (easily done): between
- the “block” above, and
- a second sense of “block” in another thing about sunscreens: the mechanism of how they protect you from sun.
With apologies for further confusion, between “sunscreen” =
- the filter particles used, and
- the formula/stuff in the bottle, as a whole
There are two kinds of sunscreen, i.e. the active ingredients, the filtering molecules used in a sunscreen lotion/cream/etc.:
- “chemical” sunscreens–that is, the actual sun filters used in the sunscreen–which absorb radiation and transform it, in chemical reaction)
- “physical” sunscreens (titanium dioxide and zinc oxide; all other sun filters are chemical), which work differently, by physically blocking radiation. (There’s also Tinosorb M, which works partly in a physical way, in combination with other filters.)
Some sunscreens are all-chemical, some are all-physical, some are a mixture of both.
Of the sunscreens that call themselves “sunblock,” most are all-physical so they’re stressing that idea that they physically block the sun.
The sunscreens that are the very best at blocking the entire UV spectrum (UVA, UVB, & UVC), as available right now, actually use a combination of filters to do their job: either all-chemical or a mixture of physical and chemical.
For more info, have a look at these notepads, they’re really helpful:
Wikipedia also has very good information, just start with the “sunscreen” article and browse around from there.
(I’m one of the people who uses all-zinc oxide sunscreen, but that’s because my skin gets irritated or worse with other filters; I’d love to be able to use one of the more advanced sophisticated ones! I also supplement the sunscreen by covering up and wearing a hat and sunglasses.)
See further: posts on here tagged “sunscreen” (just click on it below).