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View Full Version : Random Friday afternoon Science Question!

Dee
19-06-2009, 15:32
I have two bottles of suncream. One is Factor 4, the other is Factor 8.

Question: If I mix them together, will I get Factor 6, or Factor 12?

Discuss.
leowyatt
19-06-2009, 15:33
Well I would have thought you'd get Factor 12 :confused:
Blackstar
19-06-2009, 15:40
You'd get neither, it doesn't 'add' up in any way, you would simply have factor 8 or 4 depending on the ratio of mix.
Pheebs
19-06-2009, 15:41
Nope!

I don't know the ins and outs of chemical mixing and stuff so it may have some weird affect but if anything, you'd decrease the effectiveness of the factor 8 cream as in essence, you'd be watering it down.

:)
Pheebs
19-06-2009, 15:46
Thought more about it.

I'm not sure what causes the cream to protect your skin buuut I would have thought it was something that you needed to increase the amount of per bottle for it to be stronger yeh?

So like... if you have a 100ml of cream and 40ml of that is sun blocking stuff and another 100ml of cream and 80ml of that was sun blocking stuff... and then you added it together...

You'd end up with: 200ml of cream stuff with 120ml of sun blocking stuff diluted in it.

*tries to think of math*

So the 40ml of 100ml = 4/10's affective

The 80ml of 100ml = 8/10's affective

The 120ml/200 = 6/10's affective


Yeh?
NokkonWud
19-06-2009, 16:10
I could only see you having 8.
Briggykins
19-06-2009, 16:58
Two sandwiches.
Rich_L
19-06-2009, 17:07
If it didn't render either of them ineffective I guess it'd be 6.

If you believe the expert bods though, anything under SPF15 is basically useless so make of that what you will :p
semi-pro waster
19-06-2009, 17:07
You'd have factor 8 as a maximum I believe, as said it's not additive so you'd never get beyond what you've currently got as the strongest suncream.
LeperousDust
19-06-2009, 17:10
You'd be watering down the most effective, so at best 8, at worst something between 4 and 8.
Dr. Z
19-06-2009, 19:03
You'd be watering down the most effective, so at best 8, at worst something between 4 and 8.

This man speaketh the truth, from a logical mathsy POV.

However, as laymen we know that the delivery method is the cream which obviously mostly evaporates or has the moisture content absorbed into the skin leaving the protecting agent behind. If the mechanism for this was to leave a layer of UV-filtering chemicals on the skin then applying in two layers would allow you greater protection (on the assumption that the second application did not damage the first layer in any way).

To summise: Stop being a pov and go and buy better sun cream!
Garp
19-06-2009, 19:52
To summise: Stop being a pov and go and buy better sun cream!

Wot e sed. No point taking needless risks when suncream doesn't cost that much :)
Dee
19-06-2009, 20:09
My god, some of you have TOTALLY missed the point here ;D The word "rhetorical" mean anything? :p
Garp
19-06-2009, 21:24
My god, some of you have TOTALLY missed the point here ;D The word "rhetorical" mean anything? :p

But.. but.. you said

Discuss

So we did :p
Dee
19-06-2009, 22:58
Yeah? Well dont be telling ME to buy better suncream ;)
Lomster
19-06-2009, 23:17
Two sandwiches.

Its one sandwich ONE SANDWICH!!! :angry: ;D
Dunketh
20-06-2009, 00:11
6, 8, 12, I'd still get damn well burnt!
Garp
20-06-2009, 01:21
Yeah? Well dont be telling ME to buy better suncream ;)

But.. But... it's so much more fun to boss people around :(
Jingo
21-06-2009, 11:46
I'd not mix them and stick to my lovely 30 - I hate being burnt and I'm not sure which is worse- the pain or the appearance!

and it is always 1 sandwich... do not try to fob me off with less foods! :shocked:
Pumpkinstew
22-06-2009, 10:54
You'd have factor 8 as a maximum I believe, as said it's not additive so you'd never get beyond what you've currently got as the strongest suncream.

This I think. You definitely wouldn't improve the SPF by mixing an 8 and a 4.

But feel free to test it by doing several test patches and going sunbathing.;D
Fayshun
22-06-2009, 11:41
But feel free to test it by doing several test patches and going sunbathing.;D
I got paid £150 for doing similar.

I had 7 1x1 cm squares exposed to various doses of UV to burn me to varying degrees. Then after a week or so the took 6 skin biopsies for them to test. There's now 6 small scars on my right buttock. In fact my arse looks like a 6/blank domino. ;)