Cubelixa’s question…I’ve been wondering about this for quite a while now. What happens to my sunscreen if I apply it to my face in the morning and then go to work (I’m an office girl)? If I don’t do sport and sweat a lot, take a bath or rub my face with my hands, do I still have to re-apply it several times throughout the day or will it protect me just fine the entire day? What happens to it?
The Right Brain’s response:
It’s true that sunscreen needs to be replenished if it’s removed by washing or sweating or rubbing. But that’s not the only reason it needs to be reapplied. Chemical sunscreens actually “wear out” over time.
Sun damaged sunscreens
UV absorbers work by trapping high energy photons in their structure. This process excites the absorbing molecule and causes it to re-emit the energy from the photon in a harmless form. But the sunscreen molecule can only go through so many “absorb and re-emit” cycles before it begins to deteriorate. This is more common in strong sunlight and it’s why you have to reapply more lotion to maintain your Sun Protection Factor. If you’re in the office as you describe, it’s less likely to be a problem for you. U
This WebMD article provides some general details on sunscreen application that may be helpful. And here’s another source that explains that although this photodegradation of of UV absorbers is not fully understood that it can be reduced by adding stabilizing components. For instance, there is some evidence that the addition Mexoryl SX can reduce the photodegradation of Parsol 1789. Sunscreen breakdown can also be slowed down with the addition of other ingredients such as iron chelators or vitamins C or E.
This also helps to explain why you shouldn’t mix sunscreens with other lotions, you may be inadvertently messing up a formula that has been balanced to protect the photo-stability of the active ingredient.
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Dear beautybrains,
I use a moisturizer with SPF (olay total effects, which is really nice) but it’s only 15. and since it’s combined with a lotion, does it have even less sun protection? also I live in a tropical place with loads of sunshine, but i’m rarely out. throughout the day the time i spend under the sun is maybe 10 minutes in total (but it’s scorching).
Should i use more of the moisturizer or should i use a seperate sunblock or do u think it’s enough. thanks. sorry for the lengthy comment.
I’ve had a question along these lines too — if my moisturizer is a 15 and my foundation is a 10, what spf am I really wearing (I’m sure it’s not cumulative…)? Or, what happens if I put a sunscreen over the moisturizer and under the make-up — sometimes I feel like I have so much gunk on my face it’s a wonder my skin can breath at all.
Unforutnately, the two physical sunscreen ingredients that WebMD and the EWG in the article quote are zinc oxide and titanium dioxide, two ingredients that give you the dreaded “white face” after putting on sunscreen. If that still hasn’t rung a bell, remember TV shows where the father has a solid white nose? That’s zinc oxide! “Physical blocker” means just that – it puts a layer of white all over your skin, a problem for anyone who cares about their apperance, but especially those with olive and darker skin tones. Thanks, but no thanks. The most promising broad-spectrum sunscreen ingredient is Helioplex. Most women use a combined suncreen/moixturizer for convenience. The only moisturizer I’ve found with Helioplex in it is Neutrogena Visibly Even, here http://www.walgreens.com/store/catalog/Lotions-and-Creams/Visibly-Even-Daily-Moisturizer/ID=prod4198236&navCount=1&navAction=push-product?V=G&ec=frgl_&ci_src=14110944&ci_sku=sku4197106
Hey Right Brain, you mention here that chemical sunscreens break down over time, so you will need to reapply them; what about physical sunscreens with zinc oxide and titanium dioxide? If you are working in an office all day with minimal UV light exposure and aren’t sweating or rubbing or washing your face, is a physical sunscreen still effective at the end of the day?
Lara: physical sunscreens break down too and also need to be reapplied.
Jackie: You’re right; layering two products with different spf’s does not have a cumulative affect. if you have one product w spf 10 and another w 15, youre getting the protection of the spf 15. If one of those products is a foundation, i seriously doubt youre using enough of the product to get the full spf. leslie baumann’s book the skin type solution talks about never depending on a foundation for spf. if you feel you need a moisturizer and youve found one that has spf and you like it i say stick with that and use whatever foundation you like best, regardless of spf.
E: the spf is not less effective because it is in a lotion because it is formulated to work in that lotion. the problem is combining a sunscreen lotion w some other lotion.
Hi the wonderful brains,
I just wondered if you could go over the types of sunscreen as here in the UK people do not seem aware that there are physical blocks / chemical and ones that use nano tech (i am a beauty therapist and have found your guys a god send for the facts!)
Thank you
Ria xx
Hi Brains,
If I use a physical sunscreen (Invisible Zinc) do I need to re-apply in the day (if no swimming, sweating or rubbing)? Will it stay put?
Thanks
Kerence
@Kerence
Actually yes, you have to apply your sunscreen every two hours. That’s what I’ve been told by the doctors I’ve asked, no matter your physical activities. Don’t forget that the formulas are not made to last forever especially when exposed to the sun-and I don’t think it has to do with the kind of ingredients used (chemical or natural)
Great tips!
I don’t want the damage the sun can cause so I do wear my sunscreen. Nice to know WHY they recommend reapplications so often when you’re out in the sun.
Thanks!
Susanna
How do physical sunscreens break down?
“For example, when exposed to sunlight, avobenzone and octyl methoxycinnamate (octinoxate) degrade and lose sun-blocking effectiveness whereas some forms of titanium dioxide may exhibit photocatalytic activity resulting in the formation of potentially harmful free radicals.”
check this out
http://www.smartskincare.com/skinprotection/sunscreen_fundamentals.html
Based on info that cristine found, that would argue for removing physical sunscreens and reapplying rather than just reapplying.
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