I knew it was coming- SPF 100

[banquo's_bumble_puppy]

Ah, the miracles of modern science. Bet this stuff protects against nuclear fallout.....now gimmee my 6 bladed razor.....

SNAKEOIL!!!!!!!

[HenrikOlsen]

Is that an American or European sun factor?

From what I remember it's like percent/proof for alcohol, US uses numbers that are twice as large to describe the same thing.

[Strange]

So SPF99 would be OK, but SPF100 is snakeoil?

[Fazor]

I'm in need of some SPF150 or so; you know, stuff that actually sucks out some of the sun's effects that are already in your skin. I burnt the heck out of my shoulders working in the yard this weekend.

[closetgeek]

I just saw a commercial for SPF 100 this morning. I couldn't help but remember an umbrella for a patio table being rated as SPF30. How is that even possible?

[Strange]

Ah, I see (maybe). SPF is not a percentage. So SPF150 wouldn't give you negative tanning. AFAIK it is a ratio (or a factor, even): SPF100 means that after 100 hours in the sun, you will have had the equivalent of 1 hour of unprotected exposure.

[Strange]

I just saw a commercial for SPF 100 this morning. I couldn't help but remember an umbrella for a patio table being rated as SPF30. How is that even possible?

Why not? The danger is that a lot of people assume that umbrellas or clothing have a very large (infinite?) SPF. I saw something about studies of infant clothes that showed they had a very low SPF (maybe less than 10?). So even witht their skin covered they could get burned.

[HenrikOlsen]

I just saw a commercial for SPF 100 this morning. I couldn't help but remember an umbrella for a patio table being rated as SPF30. How is that even possible?
Because there's a large amount of scattered sunlight from the rest of the sky, so even if you don't get the direct sunlight there's still a lot of UV hitting your skin.

[Fazor]

Ah, I see (maybe). SPF is not a percentage. So SPF150 wouldn't give you negative tanning. AFAIK it is a ratio (or a factor, even): SPF100 means that after 100 hours in the sun, you will have had the equivalent of 1 hour of unprotected exposure.

Ah. Drats. Then the gooey aloe mess I've been using will have to do. It doesn't seem to be doing anything other than making my shoulders smell like aloe and menthol though. The annoying part was that I actually thought to put on some sunscreen (I usually don't. Melanoma be damned), but the stuff we had was a few years old and I suspect even new it wouldn't have worked that well (It was 'rated' as SPF50, but it was a spray and very watery).

[DrRocket]

Ah, I see (maybe). SPF is not a percentage. So SPF150 wouldn't give you negative tanning. AFAIK it is a ratio (or a factor, even): SPF100 means that after 100 hours in the sun, you will have had the equivalent of 1 hour of unprotected exposure.

No, SPF 100 is that you will not burn until exposed to 100 times the sunlight required to produce a burn if unprotected. It is not the most objective of measures. It also only relates to UVA. There are proscriptions in some countries as to the highest SPF rating that can be assigned.

http://en.wikipedia.org/wiki/Sunscreen

[Strange]

No, SPF 100 is that you will not burn until exposed to 100 times the sunlight required to produce a burn if unprotected.

That is a better definition than mine which (among other problems) assumed a constant level of exposure for 100 hours.


It also only relates to UVA.

UVB, surely?

[grant hutchison]

AFAIK it is a ratio (or a factor, even): SPF100 means that after 100 hours in the sun, you will have had the equivalent of 1 hour of unprotected exposure.No, SPF 100 is that you will not burn until exposed to 100 times the sunlight required to produce a burn if unprotected.And these come out differently because the sun moves in the sky: other things being equal (which they often aren't) you get a bigger cumulative UV dose around noon than you do at other times of the day.

Grant Hutchison

[NEOWatcher]

And these come out differently because the sun moves in the sky: other things being equal (which they often aren't) you get a bigger cumulative UV dose around noon than you do at other times of the day.
"These" what?
True: exposure risks dramatically change throughout the day, but since SPF is a ratio, there is no fixed amount of exposure that the computation needs to depend on.

[grant hutchison]

"These" what?These two things I quoted in my post: Strange's "after 100 hours in the sun, you will have had the equivalent of 1 hour of unprotected exposure"; and DrRocket's "you will not burn until exposed to 100 times the sunlight required to produce a burn if unprotected".

Grant Hutchison

[NEOWatcher]

These two things I quoted in my post:...
I wasn't sure, which is why I asked. Overall, those comments discuss the ratios, so do you not agree with my post?

[grant hutchison]

I wasn't sure, which is why I asked. Overall, those comments discuss the ratios, so do you not agree with my post?I agree with your post. Do you not agree with mine?

Grant Hutchison

[HenrikOlsen]

The point is that 100 hours in the sun does not equate to 100 times as much sunlight, since the amount of sunlight varies over time.

[NEOWatcher]

I agree with your post. Do you not agree with mine?
I wasn't sure what you were trying to get at. I agreed with your post, but didn't see how it applied to SPF. So I put in my 2 cents.

[Fazor]

I wasn't sure what you were trying to get at. I agreed with your post, but didn't see how it applied to SPF. So I put in my 2 cents.

Coincidentally, 2 cents provide very good sun coverage, albeit over a very small surface area.

[NEOWatcher]

Coincidentally, 2 cents provide very good sun coverage, albeit over a very small surface area.
Sun coverage maybe, but did you ever try to pick up anything metal that's been sitting in the hot sun? Ouch, a different kind of burn.

[grant hutchison]

I wasn't sure what you were trying to get at. I agreed with your post, but didn't see how it applied to SPF.Because the "100" in SPF100 means a 100-fold increase in UV dose, which does not convert to a 100-fold increase in sun-exposure time. These two things are different. That's why Dr Rocket pointed out the correct interpretation of the "100", and why Strange was happy with the correction.

Grant Hutchison

[NEOWatcher]

... and why Strange was happy with the correction.
Yes; Being that his comment was unspecified, I automatically took it as 100x equal exposure and didn't even take it as an issue. It's kind of hard to stay in the sun for 100 hours unless you're at the poles.

[grant hutchison]

It's kind of hard to stay in the sun for 100 hours unless you're at the poles.Well, just a bit inside the polar circle. Easy enough to get sunburned in the Arctic and Antarctic.

Grant Hutchison

[Strange]

Yes; Being that his comment was unspecified, I automatically took it as 100x equal exposure and didn't even take it as an issue. It's kind of hard to stay in the sun for 100 hours unless you're at the poles.

That is what I meant. But, oh no, DrRocket the Big Mathematician just has to come along and get all picky about the details :)

[NEOWatcher]

Well, just a bit inside the polar circle...
Yes; another clarification on the unspecified and/or shortened version "poles".

Easy enough to get sunburned in the Arctic and Antarctic.
I've heard that. Combination of longer total exposure and clearer skys I would assume.

[grant hutchison]

I've heard that. Combination of longer total exposure and clearer skys I would assume.And snow, which reflects UV. Worst sunburn I ever had was under my chin after a day crossing snow and ice at high latitudes.

Grant Hutchison

[Fazor]

And snow, which reflects UV. Worst sunburn I ever had was under my chin after a day crossing snow and ice at high latitudes.

Grant Hutchison

Water used to do it to us. Growing up we had a boat at the local lake (mud-hole, but that's what passes for a lake 'round here), so we'd be out on the water for hours at a time two or three days a week.

[kleindoofy]

... It's kind of hard to stay in the sun for 100 hours ...
Some people cope just fine:

http://img691.imageshack.us/img691/408/addamsmoonbath.jpg

I think this whole 100 bit is like that bull about "wind chill factor" one hears these days on weather reports. If you want to sell something (e.g. a weather report or sun blocker), come up with a way to be able to use totally absurd numbers which can somehow be justified when challenged.

Ahh, marketing. My favorite.

[DrRocket]

Well, just a bit inside the polar circle. Easy enough to get sunburned in the Arctic and Antarctic.

Grant Hutchison

Would you not expect that down parka to provide some protection ?

[DrRocket]

And snow, which reflects UV. Worst sunburn I ever had was under my chin after a day crossing snow and ice at high latitudes.

Grant Hutchison

That'll teach you Brits about the dangers of keeping your chin up.

[mike alexander]

A hundred times the standard total insolation would be, like, one hundred kilowatts per square meter.

I doubt UV would be the worst problem, but rather who would regularly apply the barbecue sauce.

[banquo's_bumble_puppy]

on the NBC news last night they said that anything over SPF 50 is probably just a waste of money....years ago they said that SPF 15 was adequate and that anything over that would be a waste...but you know there will be a 125 soon....and a 200....the sky is the limit.....until of course the suckers figure it out....I imagine there will be new products with the word 'nano' in the product name....or maybe buckyballs....or carbon nanotubes.....where there is a niche there is a product to fill it.....ear de-odorant anyone?

[Strange]

where there is a niche there is a product to fill it.....ear de-odorant anyone?

Or, where there is a product, a niche will be created. Listerine invented "chronic halitosis" as a way to improve sales of their mouthwash. Having previously failed to establish a market for it as a floor cleaner and a cure for gonorrhea.

[NEOWatcher]

I doubt UV would be the worst problem, but rather who would regularly apply the barbecue sauce.
What's the SPF of your normal BBQ sauce? And what affect would a marinade have on your exposure?


on the NBC news last night they said that anything over SPF is probably just a waste of money...
Missing a number are we?

[Argos]

Never trust SPF above 50. Beware of sunscreen infiltrating under your skin. Beware of over-confidence on sunscreen [since most people don´t use them as recommended, the effective protection could be one order of magnitude lower]. Beware of their preventing an adequate synthesis of vitamin D.

[grant hutchison]

Beware of sunscreen infiltrating under your skin.Yikes. I certainly need more detail on that one. :)

Grant Hutchison

[Argos]

Yikes. I certainly need more detail on that one. :)

Grant Hutchison

I know many people think I´m the board´s clown [there´s a clear tendency to mock anglosphere outsiders], but it is surprising, coming from you. I thought half a word would be enough. Google is your friend [but obviously you don´t need it].

[rommel543]

I think this whole 100 bit is like that bull about "wind chill factor" one hears these days on weather reports.

Wind chill does have an effect. -35c is quite easily bearable if you are dressed warmly. -25c with a wind chill of -35c is really freaking cold. The wind will cause your skin to freeze faster than just the cold air by itself.

[rommel543]

Sunblock 5000 from robocop (youtube link)

http://www.youtube.com/watch?v=SCTSCAQzY9k

[grant hutchison]

I know many people think I´m the board´s clown [there´s a clear tendency to mock anglosphere outsiders], but it is surprising, coming from you. I thought half a word would be enough. Google is your friend [but obviously you don´t need it].Argos, if I have given offence then it was entirely unintentional, and I'm sorry.
I turned up nothing that seemed relevant with a couple of Google searches. I've honestly never heard of sunscreen infiltrating under the skin, and you're telling me to "beware" of it. If I'm to beware, I do need some details on how it happens, what the dangers are, and how to avoid it. That's the whole content of my previous post, and I deliberately placed a smile at the end to indicate that no mockery was intended.

Grant Hutchison

[closetgeek]

Because there's a large amount of scattered sunlight from the rest of the sky, so even if you don't get the direct sunlight there's still a lot of UV hitting your skin.

Sun protective clothing is considered SPF 30. I can't help but wonder how lotion of any kind could offer more protection than cloth. By all means, put sunblock on underneath your clothing because light can get through. I just find it odd that lotion could offer more protection than a tarp. I do remember hearing on the news many years ago that anything over 30 is a farce.

[grant hutchison]

Sun protective clothing is considered SPF 30. I can't help but wonder how lotion of any kind could offer more protection than cloth. By all means, put sunblock on underneath your clothing because light can get through. I just find it odd that lotion could offer more protection than a tarp. I do remember hearing on the news many years ago that anything over 30 is a farce.The Clothing Protection Factor stops at 30, but the measured values can be much higher in sun-protective clothing. It's just not particularly easy or useful to quantify higher protection values, because variability between individual garments would make apparently dramatic changes to the CPF with only small changes in the UV transmittance.
Likewise, except more so, for SPF greater than 30: there's just too much variability in how the stuff is applied for these numbers to convey meaningful information to the user.
See here (http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb_C/1195733843424), for instance.

Grant Hutchison

[rommel543]

The Clothing Protection Factor stops at 30, but the measured values can be much higher in sun-protective clothing. It's just not particularly easy or useful to quantify higher protection values, because variability between individual garments would make apparently dramatic changes to the CPF with only small changes in the UV transmittance.

I wonder what the CPF would be for this....

13066

[NEOWatcher]

Sunblock 5000 from robocop (youtube link)

http://www.youtube.com/watch?v=SCTSCAQzY9k

Makes her like a blue/green Andorian/Aenar hybrid.

[rommel543]

I bet Capt. Kirk would like her..... :D

[grant hutchison]

Wind chill does have an effect. -35c is quite easily bearable if you are dressed warmly. -25c with a wind chill of -35c is really freaking cold. The wind will cause your skin to freeze faster than just the cold air by itself.Yeah, wind-chill can kill you: you get tired faster, you get hypothermia faster, you get frost-bite faster.
What vaguely vexes me is when I hear people make a fuss about wind-chill when they're referring to inanimate objects that have already cooled to ambient temperature. Your engine block gets no colder on a windy night than on a still night with the same temperature; it just cools to equilibrium faster.

Grant Hutchison

[rommel543]

And honestly like wind chill is going to matter considering the vehicle is moving..

[grant hutchison]

And honestly like wind chill is going to matter considering the vehicle is moving..Actually, I was thinking of stationary vehicles, cooling to ambient overnight. I lived in Thunder Bay one winter, many years ago, and I used to hear people talking about changing their antifreeze or plugging in their block heater, simply because of the forecasted wind chill. Some of these cars were parked in garages, too!

Grant Hutchison

[rommel543]

Anything below -10c I'll plug my block heater in for. It's just better for the engine. As for Anti-Freeze, that gets changed once every 4-5 years when I get a rad flush done.

[kleindoofy]

Yeah, wind-chill can kill you: ...
Yes.

My original comment referred to the *use* of windchill in weather reports. Many years ago it was only mentioned off hand, if at all. These days it seems to have replaced normal temperature reports entirely, as if people spent their winters strapped naked to the hoods (= bonnets) of fast moving cars.

My point is that it sounds much colder, uses lower/bigger numbers, and is therefore more dramatic and hence has larger appeal to the sensation loving masses who have become bored by reality.

I suppose a "super-chill factor" is next, to be followed on foot by "mega-chill."

[Jens]

It's kind of hard to stay in the sun for 100 hours unless you're at the poles.

Or unless you run a very fast marathon. Or more realistically, maybe if you had an SST with a pull-down top. It might get a bit windy though. :)

[jokergirl]

It's kind of hard to stay in the sun for 100 hours unless you're at the poles.

I don't even get a tan here in Sweden; I don't think anyone would get a tan from the sun at the poles, unless they're an albino.

Could be working in a tanning salon or somewhere that still works with UV lamps for exposing images though. My dad worked in a graphics studio for a while and always had tanned arms even when the rest of his body was pale.

;)

[grant hutchison]

I don't even get a tan here in Sweden; I don't think anyone would get a tan from the sun at the poles, unless they're an albino.Best tan I ever got was in north Iceland, just south of the Arctic Circle. At lower latitudes, my Celtic skin burns so easily that I just cover up all the time, these days. I've had nasty sunburns in north Norway, as previously described, and sunstroke at 7am in Sri Lanka. :lol:

Grant Hutchison

[rommel543]

I don't even get a tan here in Sweden; I don't think anyone would get a tan from the sun at the poles, unless they're an albino.
;)

While living in the Yukon it wasn't sun 24/7 during the summer but it went down around 2am and back up around 5am. Normal temperature is 22-25c and because it's a desert climate you get a lot of time with the sun.

[Fazor]

I suppose a "super-chill factor" is next, to be followed on foot by "mega-chill."

I'm still waiting for the wet-wind-chill factor; you never know when someone's going to spill something on you, and it's important to know exactly how cold you will feel if you're wet and there's wind.

[Argos]

I turned up nothing that seemed relevant with a couple of Google searches. I've honestly never heard of sunscreen infiltrating under the skin, and you're telling me to "beware" of it. If I'm to beware, I do need some details on how it happens, what the dangers are, and how to avoid it.

I was referring to the carcinogenic ingredients of sunscreens, which, according to all sources I´ve searched, can sip through the skin. It´s very simple. Unfortunately I don´t have any .edu site to link to, but references are widely available on the Internet. I mentioned that because of an article I read a few days ago in a serious website [I can´t remember which one] about this very subject.

[grant hutchison]

I was referring to the carcinogenic ingredients of sunscreens, which, according to all sources I´ve searched, can sip through the skin. It´s very simple. Unfortunately I don´t have any .edu site to link to, but references are widely available on the Internet. I mentioned that because of an article I read a few days ago in a serious website [I can´t remember which one] about this very subject.Ah, the sunscreen "controversy". I didn't realize that's what you were referring to, sorry.
It's certainly easy to find references to "sunscreen causes cancer" on the Internet. It's much harder to find an actual dermatologist who doesn't wear sunscreen.

Grant Hutchison

[Argos]

It's certainly easy to find references to "sunscreen causes cancer" on the Internet. It's much harder to find an actual dermatologist who doesn't wear sunscreen.

I may have left the impression that I´m somehow 'against' sunscreen, which is not true. In fact I wear sunscreen since 1992. I´ve already extracted 6 pre-malignant lesions and there´s more to come, since I´m a high risk patient. I keep constant watch. That´s why I worry about excessive use.

[TheOncomingStorm]

Sunblock 5000 from robocop (youtube link)

http://www.youtube.com/watch?v=SCTSCAQzY9k

I think I saw her in Avatar.

[NEOWatcher]

Interesting to note that we have been talking about the SPF in terms of amount of exposure. But; in the following article:
Worst sunburns scorch and sizzle -- 5 ways to avoid getting deep-fried (http://www.cnn.com/2010/HEALTH/05/28/sunscreen.safety.tips/index.html?hpt=Sbin)

They point out why the higher SPF's are not that important. It comes down to a simple matter of the inverse of the ratio.

Research shows that an effective SPF 15 can block about 93 percent of all incoming UVB rays, SPF 30 blocks 97 percent and SPF 50 blocks 98 percent.
The protective factors plateau from there, Ostad said. A product with SPF 100+ blocks about 99.1 percent of the UVB rays.
Why they needed "research" on this, I'll never know. It's just a matter of looking at it from a different point of view.

[grant hutchison]

They point out why the higher SPF's are not that important. It comes down to a simple matter of the inverse of the ratio.And a little unevenness in your application of sunscreen can make a bigger difference to your exposure than (say) the difference between SPF50 and SPF100. The error bars in everyday use are too big to justify using the high SPF numbers, as would be much more evident if the filtering effect were quoted instead: I doubt if anyone would see a 99% filter as much improvement on a 98% filter, and all would appreciate that a carefully applied 98% filter might be better than a carelessly applied 99% filter.

Grant Hutchison

[Romanus]

Ack! Rommel beat me to it!

;)