Activated Charcoal and Charcoal in Skincare: Does It Work to Purify Your Skin?

Recently I've been seeing lots of charcoal-based skincare products around, along with claims that would make anyone sit up. The main argument is that applying charcoal to your skin will help to purify your skin. Thus, marketers tend to stress charcoal as pore-clearing, acne-reducing, skin-detoxing wonders. There are so many products out there, all with the same marketing talking points. Some products even stress that they have activated charcoal, no less (all it really means is that the charcoal is more porous and thus allowing a larger surface area for adsorption, but by and large its chemical properties will be the same). Just take a look at the graphic I've helped you guys put together, and you'll know what I mean:

Lookit all those charcoal-laden products! If such products work, why don't we all have awesomely detoxed skins?

So there is a lot of charcoal-laden skincare out there. But is there any truth to all the claims these products make? That's a question that's worth answering.

Want to Prevent Wrinkles? Stop Smoking - Even if it's Light Smoking

You guys know that increasingly for skincare reviews, I seek to incorporate actual references to scientific literature, because it makes for a much more informed and credible review that cuts through the hype (if you've missed those reviews, you can take a look at my Elizabeth Arden Ceramide Capsules review, my review of the Kiehl's Powerful Wrinkle and Pore Reducing Cream, and the Powerful Wrinkle Reducing Eye Cream, and the Lancôme Advanced Génifique Youth Activator review). And the other day, I came across this paper I thought you guys might like to know!

The paper is called "Smoking and skin aging in identical twins.", and what makes it so interesting is that although I've always known that smoking ages you, I've never really gotten to see a compare-and-contrast case study that can serve as a way to visualize the difference. But now we do, thanks to twins!

In this study, the researchers took a look at a set of identical twins (so same genetics) with very similar lives to each other (lived in same town for 30 years, similar lifestyles with minor differences etc.), and the main difference was that one twin smoked, and the other twin didn't. Essentially this allowed for the researchers to conclude that any significant difference in appearance was quite possibly due to one smoking and the other not. In their words: "In this pair of twins with an identical genetic background, minor medical histories, and similar significant sun exposure histories, the clear difference between twin 1 and 2 was the extensive history of tobacco use in twin 1 that was absent in twin 2. This variable likely served as the major contributor to advanced skin aging in twin 1."

You can see the results below:

Twin 1 smoked, Twin 2 didn't. (Image source)
Now the first thing I'll say is that both ladies look great. They look energetic and full of life, and their eyes sparkle with personality (their eyes that are a lovely shade of blue, too!). And really, if you think about it, at the end of the day, your personality is what matters most, instead of trying to compare the number of wrinkles a person has. But since this post is meant to be a cautionary tale about the effect of smoking on skin from a beauty blog perspective, I will do the horrible and delve into the superficial. (Aww, just cut me some slack here. How many beauty blogs do you know that even write about smoking and health?)

You can indeed see a difference in wrinkles caused by smoking, although perhaps, not as severe as one might expect. But bear in mind - even the smoking twin didn't smoke all that much. The study reports that she smoked in the "approximately 52.5–pack-year" range, which is actually a pack a week. Given that a cigarette pack holds anywhere from 20 - 25 sticks, Twin 1's smoking habit was definitely very light, probably a 2-3 sticks a day. And yet, even at this very light rate, the difference is visible. If the researchers had used a set of twins where one smoked a lot more (say, a pack a day, still within the "light" range), then you can imagine the difference will be much starker.

So yes, it does seem that if you're smoking, you're more likely to get wrinkles, and this applies even if you're smoking just "a couple of sticks a day". The study demonstrated that those couple of sticks do add up over time - just like UV exposure, the damage seems to be cumulative. And this is particularly relevant for young adults, because even while heavy smoking has decreased in general, the number of young adult light smokers has been increasing over time. Perhaps such people feel that because their smoking is light/intermittent/infrequent, they aren't damaging their health by doing it, but that's not true. In fact, "low levels of tobacco exposure as seen in light smoking (4–7 cig/day) has about 70% of the effect of heavy smoking (≥ 23 cig/day)" (original source), because the dose-effect relationship is "highly non-linear". Wrinkles are just one part of what happens when you damage your body by smoking, even light smoking.

So there you go - I'm sure you knew it all already, but yes, smoking harms your health, even if it's the light kind of smoking that is deemed socially acceptable. Really, when it comes to smoking, any dose is bad for your health. But for those who don't care about their health, then perhaps, as the study's authors muse, "wrinkles, rather than the deadly consequences of smoking, may prove to be the most powerful motivator for smokers to stop smoking."

Collagen Skincare and Supplements: Do They Work?

Over the past few years, collagen has been one of the buzzwords in skincare - every other brand out there has some sort of cream or mask with collagen in it. The claims are quite hyperbolic, claiming to restore elasticity, and reverse the aging process. I've been having quite a number of conversations with friends, co-workers, other beauty bloggers, and so on about collagen in skincare, so I thought to save myself all tht saliva I wasted telling everyone individually, I'd just blog about it here, and refer everyone to my blogpost instead (if I think they are the type of person who would read a beauty blog, I guess!). Basically, these products market themselves on the premise that applying collagen to your skin will replace the collagen lost as a result of aging. Just take a look!

So much hype, so little proof. Sigh.

Unfortunately, putting collagen creams, lotions, serums, masks or what-have-yous on your skin will not help replace your skins collagen. But why?

The 500 Dalton Rule

Molecules (whether they're collagen, or whatever) need to be small enough are to penetrate through the layers of the skin and be absorbed. As a guideline, this limit is often cited as 500 Daltons. In fact, this guideline is so well known that often cosmetic chemists and dermatologists refer to this as "The 500 Dalton rule". Now there are exceptions to the rule, but generally, the reason why 500 Daltons rule is generally accepted is because: 1)almost all common contact allergens are under 500 Daltons. Larger molecules cannot penetrate the skin and cause allergies; 2) the most commonly used pharmacological agents applied topically are all under 500 Dalton; 3) all known topical drugs used in transdermal drug-delivery systems are under 500 Dalton.

A useful corollary of the 500 Dalton rule is that the next time, if you get some marketing spiel trying to brainwash you into buying their "natural" products on the grounds that "the chemicals you put on your skin are toxic and will enter your organs and blood through your skin" (sounds crazy, I know, but some parts of the internetz are pretty aggressive about this point of view), then you can call their bluff, because by and large, most molecules as found in skincare (both the natural and "chemical" variety) are much larger than 500 Daltons. Truth is, very little in skincare penetrates our skin. If it did, it wouldn't be a cosmetic anymore - it would be a drug, and would be subject to stricter regulation. But let's get back to collagen!

Applying the 500 Dalton Rule to Collagen

So how does this 500 Dalton rule help us understand how collagen in skincare works? Collagen (including collagen "extracts" in skincare) has a molecular weight of 15000 to 50000 Daltons, so they are waaay bigger than the 500 Dalton limit needed to ensure that they will pass through and be absorbed by the skin. Some products advertise that they have "smaller collagen" that will be able to be absorbed by the skin, but this is just not the case. In fact, when I tried to look up exactly what these manufacturers meant by "smaller", the best I could find was collagen in the range of 2000 Daltons and up, which still isn't going to penetrate your skin. The truth is, it's all a marketing play, as there is no real benefit from collagen applied topically - it doesn't get absorbed into your skin, but it just sits on top of your skin.

Sure you can slap it on your face, but it won't help anything. (Image Source)
So, if collagen doesn't actually penetrate your skin, then what does it do when you apply it to your skin? Well, firstly, collagen on top of your skin can function as a humectant, and this helps to moisturize your skin. But there are a lot of other equally cheap and effective humectants out there, such as glycerin and urea. So you don't really need to spend all that money putting collagen on your face when any old cream with glycerin would do the trick.

Secondly, the collagen in some creams also form a film on the skin that gives the appearance of smoother skin by filling in surface irregularities. Such creams that have this effect on skin are typically also formulated with other proteins/peptides in them to enhance the film-forming effect. But, as you might guess, this is a temporary effect - it's gone as soon as you wash your face, and wash the film off. It definitely does not have any long-term effect.

The collagen you're applying, is the "triple stranded collagen molecule". Unfortunately, it totally ignores the fact that collagen doesn't exist in isolation.(Source: Essential Cell Biology, 3rd Ed., by Bruce Alberts.)

Even if somehow you managed to get some collagen from your skincare into your face (I don't know how that would be possible, but assuming somehow that hypothetically it happened), it still wouldn't work. This is because it would not be able to incorporate itself within the complex collagen structure in the skin. Collagen in your skin doesn't exist in isolation - it's not like you have individual bits of collagen floating around in your skin and somehow stuffing more collagen into that space will help to plump it up. Collagen is actually part of a larger structure within the dermal layer of your skin, which includes other important components, such as elastin, hyaluronic acid, and so on. The collagen fibres in your skin are "woven" in a wickerwork pattern (yes, like the baskets), which gives them mechanical strength. So any collagen that might pass through your skin will still not be incorporated into the pre-existing structure. As an analogy, if you had a shirt with a hole in it, and you tried to patch the hole by putting a bunch of broken up threads on top of the hole, it wouldn't work. The same thing applies to trying to "fix" your skin with collagen.

The wickerwork structure of collagen in your skin. This is an actual closeup photo of collagen in your skin! (Source: Tissue Mechanics, by Cowin & Doty.)

If in fact you did want to help collagen synthesis within your skin, there are other things you could apply to aid this process that have scientific literature to back up their efficacy (Vitamin C or ascorbic acid, retinoids, and niacinamide are just a few examples), but applying collagen simply isn't one of them.

What About Eating Collagen?

When I tell most of my friends this, they immediately follow up by exclaiming, eureka-moment style, "Oh! So I should be eating collagen supplements instead of using collagen creams!" Oops. Unfortunately, eating your collagen won't work either. It might be tempting, though - there are so many, many brands of collagen out there - Fancl, DHC, Meiji, the list goes on. And they all advertise themselves oh-so-scientifically:

Marketing Folks: "Darn, now people know collagen in skincare doesn't work. Let's hope we can persuade them to eat it instead!" (Image source)
What happens when collagen is ingested? Well, collagen is really a type of protein, and all proteins are composed of amino acids. So, collagen (like any other protein) gets broken down into amino acids, and thus they don't jump straight undigested from your stomach to your skin. So unfortunately, while such products claim to replenish the collagen in your skin with collagen that you eat, the truth is, once you eat it and start off the digestion process, by the time your small intestines absorb it, it's broken down to amino acids, just like any other protein. This is where a little bit of science can help a long way. Everyone knows that if you eat a piece of steak, the steak will not end up under your skin wholesale in exactly the same form in which it was eaten. So why do we believe that when we eat collagen supplements (tablets, powders, whatever), it will end up in our skin as collagen in the form that was eaten? The truth is, both the steak and the collagen supplement are digested in the same way at the end of the day - into amino acids your body uses for a variety of uses. But we fall for the marketing (did you see the picture above, man? That's some hardsell tactics!), and it is combined with a simplistic and seductive but flawed logic (collagen in = collagen out), and this combination makes us leap to the wrong conclusion.

How protein is digested in your body - this applies to both the steak, as well as collagen. (Image source)

Also, you can get your amino acids from plenty of other protein-rich foods - meat, dairy, beans, tofu - you know, actual food. There's no need to spend extra for collagen supplements. While they're not harmful, there's probably no extra benefit you're going to get from them - you supply your body with amino acids, but it's not like you can't do the same through a healthy, well-balanced diet. Besides, collagen supplements aren't cheap, and there's a much cheaper alternative available. If you do want to eat collagen, instead of splurging on a collagen supplement, you can eat gelatin - it's cheaper, and is what collagen supplement and skincare marketers have been calling "hydrolyzed collagen" (aptly called because gelatin is in fact formed from the hydrolysis of collagen). This is why companies such as PB Gelatin, Nitta Gelatin and Rousselot Gelatine, which manufacture gelatin for the food and pharmaceutical market (in the pharma industry it's sometimes used as a coating material for capsules and the like), are also able to manufacture a line of collagen for supplement use. It's because they're pretty much the same thing. So, instead of eating collagen, you could just eat gelatin, it's definitely cheaper, and possibly yummier too (who doesn't love jello? I love me some jello!).

If you need a collagen supplement, you may as well eat this. (Image source)

But my Collagen Supplement is FDA Certified! It Must Work, Right?

Explaining this fact of digestion to some of my friends might sometimes make them confused. They might then ask, "But I saw XYZ MAGIC BRAND of collagen supplement was 'approved by the FDA' or 'FDA certified', so it must work, right?" Once again, a little knowledge will help here. Contrary to popular belief, the FDA does not regulate supplements of any kind. Let me repeat that: The FDA does not regulate supplements. The FDA's does in fact do tons of regulation, but it is primarily for medical implantables and medical equipment (so things like pacemakers, stents, X-ray machines, physiologic monitors, and hand-held surgical instruments), and for drugs, both the prescription drugs, as well as OTC drugs (like anti-dandruff shampoo). These types of products do require their manufacturers to carry out tests to prove that the product is safe for use and is effective, depending on the classification of the product (invasive products go through more rigorous testing than non-invasive ones, and prescription drugs go through more rigorous testing than OTC products).

Stuff the FDA actually regulates. Supplements, however, are not under FDA regulation. (Image source)

So now, what about supplements? Like I mentioned before, the FDA does not regulate any of them. Not collagen supplements, not vitamins, not herbs, not anything. In fact, let me quote directly from the FDA website: "a firm is responsible for determining that the dietary supplements it manufactures or distributes are safe and that any representations or claims...are not false or misleading. This means that dietary supplements do not need approval from FDA before they are marketed." And again, also from the FDA website: "Dietary supplements are not (Italic emphasis theirs) approved by the government for safety and effectiveness before they are marketed. If the dietary supplement contains a NEW (all-caps also theirs) ingredient, that ingredient will be reviewed by FDA (not approved) prior to marketing — but only for safety, not effectiveness." (If you want more on this topic, this LA Times Healthy Skeptic Column article is a pretty useful overview.)

So how does this info relate to collagen supplements? Since collagen supplements are classed not as a drug, but as a supplement, it means that 1) the company making the collagen supplement does not need for it to be approved by the FDA before selling it on the market, and 2) even if there is some new ingredient, the ingredient is only reviewed for safety (i.e. FDA will ensure that it won't kill people or make people sick), not efficiency (i.e. FDA will not ensure that it will actually work to cure baldness, grow hair, or replenish collagen). So while companies selling collagen supplements (or any other kind of supplements, for that matter,) like to claim that they are "FDA certified" or "FDA registered", it's really a marketing sleight-of-hand that is intended to make the consumer think that the FDA has somehow verified that their product works, when they really don't. And of course, if a company claims that their supplement is "FDA approved", then they are just not being honest at all, since FDA doesn't approve supplements to begin with. We have already seen that collagen supplements are really just broken down into amino acids in the body, just like any other protein. A company claiming FDA certification isn't going to change how your digestive system works on ingested collagen.


Sudden Clarity Clarence has also just had an epiphany.
Conclusion: Nope, You Don't Need It!

Anyway, I hope this has helped provide a sanity check on some of the hype around collagen skincare and supplements. Most of these are really marketing gimmicks and not much else. Instead of spending money on these creams and supplements that don't work, it might be wiser to spend money on a good sunscreen instead, because UV exposure is definitely one of the major contributors to aging! Since I'm something of a skincare nut, I do also have a post on sunscreen tips and information you should know, but if you want to see me put some of these principles into action, though, you can also check out my review of a collagen supplement here.

Homemade Natural Face Scrub Recipe: DIY Skincare!

Guess what guys? I learnt how to make my own DIY face scrub! I actually learnt it at the Bellabox bloggers event recently, and I was so excited, I had to share it with everyone! The following recipe was kindly shared by Petronille Houdart, the founder and the brains behind Petronille, a French brand with very good skincare. She actually formulated Petronille's products (I have one I want to share with you soon), and is extremely knowledgeable about her ingredients, products and everything!

Don't believe me? Look at what I made under her direction!

Here is the recipe she shared:

For 30g of Scrub:

1. Your choice of:
Himalayan Salt: 1.5 cup*, or
Brown Sugar: 1.5 cup*

2. Your choice of:
Sweet Almond Oil: 1 cup*, or
Olive Oil: 1 cup*

3. Your choice of:
Multiflower Honey: 1 tsp, or
Coconut: 1 tsp, (ours was ground into powder) or
Cacao: 1 tsp (what we used was also ground into powder)

4. Your choice of:
Tea Tree Essential Oil: 2 drops, or
Ginger Essential Oil: 2 drops

*These aren't actual cooking cups. Because we were only making 30g of scrub, we used much smaller little bowl-like cups, sort of like those you use for jello shots? Sort of like this:

(Image source)


To start off, we cleaned the insides of our little containers with 70% rubbing alcohol to sanitize the containers. Then we began mixing the ingredients in the order as shown above: first the choice of salt/sugar, then the oil, then the honey/coconut/cacao, then the essential oil (not strictly necessary for the scrub, it's more for fragrance), mixing well after each step. To mix, we used simple wooden coffee stirrers.

To me, it seemed like the key to this was getting the right proportion of salt/sugar and oil. Too much salt/sugar and the scrub would be pretty dry, and too much oil and the scrub would be too liquid-y. Using that container of ours, we filled it up to about 3/4 full with the salt/sugar, and then added the oil until the container was pretty much full. And then we stirred and stirred to get the two to mix.

Here's a shot of the bottle of scrub I made close up so you can see the scrub texture. Although there a lot of solid grains in there, they're well mixed up in the oil.


The mixture will last about 2 months or so. According to Petronille, although there are no preservatives added, it will not go bad, because there is no water (everything is oil and other solids). She also added that it would make a great gift, if you ever do it yourself, because it's cheap, yet a very thoughtful idea, and I have to agree - if you've got a friend who's a skincare nut, this would be a perfect gift!

And there you have it - the most awesome thing I've learnt with regards to DIY skincare so far! (Thanks Petronille!) If anyone gets to try out the recipe at home, let me know your thoughts!

Sunscreen: 5 Overlooked Tips You Need To Know

Summer is round the corner, and all the drugstores in the West are stocking up their aisles with rows and rows of sunblock of various kinds. In Asia, sunscreen is an ever-popular item, so we always have lots of it all year round. As a skincare fanatic, I thought I'd share some useful tips I've learned regarding sunscreen, especially since there is a lot of misinformation about sunscreen.

(Image by Ling)

Most of us already know about the basic sunscreen tips, e.g. reapply every two hours, etc. This blogpost intends to discuss deeper issues that are equally important. Some of these issues can be really, really technical (if you read published literature on it, you'll know what I mean). Since this is meant to be an introductory post for the average, non-skincare-fanatic girl, I've done a lot of oversimplification, in order to get the points across. And to make it more entertaining (a long block of text is boring after all), I've even thrown in cute pin up girls with lame captions. So without further ado, here are my 5 tips:

1. Just Looking at the SPF Number is Not Enough

It always surprises me how most people think that as long as a sunscreen's SPF (Sun Protection Factor) is high enough, they're covered. Not quite - there are two types of ultraviolet rays produced by the sun that hit the skin - UVA, and UVB (there's also UVC, but that's absorbed by our ozone layer, so you don't have to worry about it). Both UVA and UVB damage the skin - they can damage collagen fibres in the skin, as well as cause free radical damage. UVA however, doesn't cause sunburn, whereas UVB does. It's a lot more complex than that, but I'm oversimplifying here.

(Image source. Text and editing by me.)
Now, the SPF number in a sunscreen is only the measure of protection against UVB rays. Basically, the higher the SPF, the greater the protection you get against UVB rays. Of course, this leaves out half the story - you don't know anything about whether the sunscreen can offer protection against UVA rays. So even if you slather sunscreen all over your body, if it doesn't have much UVA protection, you will still subject yourself to sun damage. In fact, you may be worse off, because you won't burn as quickly despite exposure to UVA rays, thus you may end up staying out in the sun for longer.

So how do you determine whether a sunscreen has good UVA protection or not? This is where it gets tricky. Unlike SPF, which is pretty much well-defined the world over, there is no universal standard for UVA protection. In some countries, typically in Asian countries, you see a PA value, e.g. PA+, PA++, PA+++ and so on. This is an indication of UVA protection, and the more ++'s after the PA, the higher the UVA protection. You see this a lot on Japanese sunscreens. In my experience, I rarely see any sunscreens beyond PA+++. In other countries, such as some European ones, they use PPD (Persistent Pigmentation Darkening) as a measure, followed by a number, e.g. PPD 4, PPD 8, PPD 12 and so on (I don't often see sunscreens with more than PPD 12). Like SPF, the higher the PPD value, the greater the UVA protection. In the USA and other countries (see Edited to add note a few paragraphs down for US FDA sunscreen guidelines changes), there isn't any standard way to label UVA protection, so most sunscreens will mention something like "broad spectrum protection" on the packaging. If, in the absence of PA or PPD information, you see this, it's generally a good indication that it has some protection against UVA rays too. So the bottom line is - don't just look at the SPF number. Check to see that it offers UVA protection too.

1a. A side note: SPF Numbers Can be Misleading

So now that you're aware about choosing a sunscreen with broad spectrum protection, I'd like to clear up one last misconception about SPF. In Asia especially, girls like to go for crazy high SPF numbers in their sunscreen (here you see SPF 130 sunscreens and SPF 100 sunscreens quite commonly). They somehow feel like it's the strongest type of sun protection they can get. However, a higher SPF doesn't really mean a higher level of protection - past a certain point, the additional protection offered is less and less, as sun protection protection doesn't increase linearly with SPF number. So a SPF 30 sunscreen will have a greater incremental effect when compared to a SPF 20 sunscreen, but an SPF 80 sunscreen may not be all that much different from a SPF 70 sunscreen. And, a SPF 100 sunscreen does not actually offer twice the amount of protection that an SPF 50 sunscreen does. Case in point - an SPF 15 sunscreen absorbs 93% of UVB rays. An SPF 30 sunscrreen absorbs 97% of UVB rays. An SPF 50 sunscreen? 98%. That's why some countries (mainly European ones, and most recently the USA) have regulations demanding that you can't label your sunscreen with a number above, say, SPF 50, becuase the SPF number can be misleading for the average consumer. In these countries, anything above SPF 50 will just be labelled SPF 50+. But where I live, companies go crazy advertising uselessly high SPF numbers, and ignorant consumers snap these up like candy.

Updated to Add: Here's a handy chart. As you can see, the sky-high SPF value really confers only incremental benefits when it comes to sun protection, once you hit SPF 30 (which provides 97% protection). So, if you're thinking of spending top dollar on that SPF 20000 sunscreen, just opt for an SPF 30. I personally use SPF 50 for my daily use, but then again I'm an Asian girl aspiring to Twilight-vampire-like pale skin. So there.

(Image source, which uses data from EPA & FDA.)
But anyway, enough about my rant. Let's move on to the next point.

(Edited to add: I must have a sixth sense or something, because a couple of months after I wrote this article, the FDA unveiled some changes to sunscreen guidelines, which would affect the claims manufacturers can place on their packaging. This includes making it mandatory for sunscreens to offer effective UVA and UVB protection in order to claim being "broad spectrum", and requiring any sunscreen with SPF values of more than 50 to be marked SPF 50+. That's better, isn't it? You can read more here.)

(More Edited to add: This isn't really in the scope of an introductory blogspot, but this really interesting blogpost has further info on why SPF numbers can be misleading - basically he argues that other ingredients (namely antioxidants and anti-inflammatory ingredients) can skew the SPF measurements by making them seem higher than they really are. The bottom line is to look not just at SPF number, but also at the level of UVA protection offered.)

2. Know Whether Your Sunscreen is Physical or Chemical

Sunscreens offer protection in two ways - physical, and/or chemical. A sunscreen can be purely physical, purely chemical, or both. Physical filters utilize ingredients (there are really only two, titanium dioxide and zinc oxide) to reflect and scatter the sun's rays. So basically, these ingredients sit on top of your skin, and deflect the sun's rays away from your skin (I oversimplified, but you get the idea). So they physically block the sun's rays. Chemical filters (avobenzone, octocrylene etc) work differently. These absorb the incoming UV rays, and then "convert" them to heat (another oversimplification, but I hope it makes things clear).

(Image source. Text and editing by me.)

So, you may ask, what's the difference between the two? Well, physical sunscreens are less cosmetically elegant - so if you get that white cast on your face, it's usually due to the physical filters in your sunscreen. In addition, physical sunscreens tend to be thicker, and more opaque, and thus tend to have a heavier texture, which some people don't like. On the bright side, they are generally more photostable, and they are generally agreed to be less likely to aggravate sensitive skin. Chemical sunscreens tend to have a better texture, as they tend to be colourless and more watery in texture (a lot of Japanese sunscreens are like this), and don't give you "white sunscreen face", but on the other hand, they tend to aggravate some types of sensitive skin more. Some badly formulated ones can sting and burn sensitive skin. (There's also a concern about chemical sunscreens being xenoestrogenic, but I won't go into that, as I don't have much expertise in the area.)

Thus, if you do have sensitive skin, it is a good idea to look out for a physical sunscreen. Often I get feedback from my female acquaintances telling me about how this or that sunscreen cause them skin sensitivities, and when I check, they're invariably using a sunscreen that's heavy on the chemical filters. Of course, this is an over-generalization because everyone's skin is different, and there are lots of ways to formulate sunscreen (the base, in addition to the active ingredients, could contain irritating compounds). But if you have sensitive skin, it's worth bearing in mind. The bottom line - there's a tradeoff between cosmetic elegance and skin aggravation. You have to find the balance, and it starts by knowing the difference between physical and chemical filters.

Updated to add: So as far as choosing sunscreen goes, a good idea is to look out for two things: a sunscreen with both UVA and UVB protection, as well as a sunscreen whose filters, whether chemical or physical, are less likely to aggravate your skin. Here's a neat chart that summarizes some of the commonly used sunscreen filters, whether they are chemical or physical (like I said, there are only two physical filters), as well as the level of UVA and UVB protection they provide.

(Image source, using data from EPA & FDA.)
If the above list sounds very short, it's because the FDA only lists down the INCI names, not the brand or trade names these are sold or marketed under. For example, Helioplex (you may have seen it on Neutrogena sunscreens) is actually a combination of avobenzone and oxybenzone, not an entirely new sunscreen filter altogether. Also, as this is a chart from the FDA, it doesn't include filters approved elsewhere (e.g. Europe) that have not yet been approved by the FDA. For a list of some of these, you can see here (or scroll down to the end of this post, where I have the table in a picture form in the annex).

3. Layering SPF Products Does Not Work

Another common question I get is, "If I use an SPF 15 moisturizer, and an SPF 20 sunscreen, will I get SPF 35 on my face?" I hate to break it to these girls, since I see so many people doing this, but the answer is no. Then said girl will invariably ask, "Or is it just SPF 20, since that's the higher of the two?" Once again, no.

(Image source. Text and editing by me.)

The reason why SPF 15 + SPF 15 doesn't = SPF 30 is because some SPF ingredients can interfere with each other, or stabilize each other. This has to do with issues of photostability in the sunscreen. Some ingredients degrade other ingredients, thus offering less protection overall. A commonly-cited example is uncoated titanium dioxide or zinc oxide degrading avobenzene. In other words, if you have a sunscreen containing zinc oxide, and another sunscreen containing avobenzene, it is not a good idea to use them together or layer them on top of the other. Other ingredients, on the other hand, stabilize each other - for example, avobenzene is stabilized by specific amounts of octocrylene, so they are often used together in sunscreen formulations.

The reality is, it's hard to tell how a sunscreen will react with another sunscreen, unless you know specifically what the active ingredients are, and how they would react with each other. But we aren't all PhD holders. So the easiest way is to just have only ONE product with SPF in your routine (that is, the sunscreen) and apply that properly. That way, you can be sure it won't have any other sunscreen ingredients to interfere with its effaciacy. Don't get a moisturizer with SPF, a foundation with SPF, and try to layer them both with a sunscreen. That's just a waste of all that sun protection in the product.

(On a side note, this is why I absolutely HATE moisturizers and foundations with SPF protection. They get in the way of my sunscreen. Unfortunately, every other new moisturizer or foundation has SPF inside, thanks to the laws of supply and demand. Stupid uninformed consumers demanding SPF-infused products which shouldn't have SPF stuff inside. Grr.)

Which brings me to my next point.


4. Apply Your Sunscreen Properly

I'm always amazed by girls who spend a pretty penny on their sunscreen, but can't be bothered to apply it properly. I mean, if you're going to apply it at all, make sure you do so properly, if not you won't get the full protection of your sunscreen. There are two major issues with application that I will go into: not applying enough, and excessive rubbing.

4a. Not applying enough

Do you know how SPF is calculated? It's calculated by measuring the amount of UV protection afforded by the sunscreen, using 2mg of sunscreen per cm2 of skin area. Yes, 2mg/cm2. Use any less, and you'll be getting less than the stated SPF on the bottle.

So, what does 2mg/cm2 of sunscreen look like on your face? This should translate into half a teaspoon for your face and neck, and half a teaspoon for each arm (this is an approximate measurement, and would vary with the surface area of your face/neck/arms). Most people I know don't use anywhere near to the correct amount of sunscreen, even though they buy really expensive sunscreen products. That's a pity. Remember, always use at least half a teaspoon. If in doubt, use more rather than less. How much you use determines how much protection you get.

(Image source. Text and editing by me.)

Now, on to the next mistake when it comes to sunscreen application.

4b. Rubbing Your Sunscreen

Sunscreen is supposed to sit in an even, unbroken layer across the surface of your face. That's how it reflects/scatters/absorbs the UV rays before they hit your skin. So when applying your sunscreen, that should be your aim. Rubbing or buffing in your sunscreen will break the even layer across your face, and affect its effectivenss. I know the temptation to rub it into your skin can be strong, but yes, it is supposed to sit on top of your skin to work properly. It's sunscreen, not skincare.

As a corollary, it also irritates me when people put on sunscreen, and then buff or rub their foundation on top of the sunscreen. By doing so, the sunscreen's efficacy has been lessened. I guess for people who use makeup on top of their sunscreen, rubbing and buffing will be inevitable - the only tip then would be to keep the rubbing to a minimum.

Both points 3 and 4 above bring me to my last point which is...


5. Sunscreen in Non-Sunscreen Products is Useless

Well, not quite useless. But generally, unless these products are used and applied like sunscreen, you aren't likely to get much UV protection from these products. And by "used and applied like sunscreen", I mean 1. applying as much of the product as you would sunscreen (remember, 2mg/cm2), and 2. Not rubbing or buffing it into your skin, and 3. not layering products.

(Image source. Text and editing by me.)

Now you see why sunscreen in non-sunscreen products, like moisturizers, foundations, and powders, is so useless. First of all, noone applies 2mg/cm2 of foundation to their face. You'd end up with a very cakey makeup look - not great. Same for moisturizer and powder. So in reality, although SPF 15 in that foundation may sound great, unless you apply half a teaspoon of foundation for face and neck, you're not getting anywhere close to SPF 15. In fact, this post on Futurederm (written by Nicki who is herself a med student) estimates that "your average SPF 15 powder is giving you a true SPF of 1.1, and your SPF 15 moisturizer is giving you actual protection of SPF 8 to 10 with average application".

(Edited to Add: If half a teaspoon seems hard to visualize, here's a really good post on FutureDerm written since the time this blogpost went live, where John pours out the requisite amount of sunscreen into his palm (he's using approx a quarter of a teaspoon, calculated on the surface area of just his face only, not including the neck). Now imagine that you want to get your full SPF20 from your foundation. Are you really going to apply that much foundation? I definitely wouldn't want to use that much foundation on my face - it would be too much makeup.)

The second issue is to do with buffing and rubbing. When you use moisturizer, foundation, or powder, or other makeup product, you're supposed to buff and rub. I mean, a skilful makeup application means lots of blending, right? Unfortunately, it also makes for very lousy SPF coverage. This means to get SPF 15 of coverage listed on your foundation, you'd have to use half a teaspoon of foundation, and try not to blend it in. Eeks.

Lastly, of course, you can't layer SPF products (or you can, but the active ingredients may interfere with each other). I've already written about this, so I won't go into details again. So now you can see why I hate foundations, powders, moisturizers, etc with sunscreen in them. They're really more a marketing gimmick than anything else, since most people would use these products in a manner which would render very little, if any, UV protection at all.

(Image source. Text and editing by me.)

So there you have it, the five most useful sunscreen tips I've ever encountered. I know I've oversimplified here and there, sometimes a lot, but I hope that it makes some of these very technical issues a little easier to understand, so if anyone wants to chime in with their two cents worth, please do so and leave a comment! There's lots of scientific literature out there, so if anyone wishes to delve deeper into any of the abovementioned points, there's a lot of reading (the Skincare board on Makeupalley is a great place to start). Good luck, and happy sunscreen-ing yourself!

Annex: Full List of Sunscreen Filters

This super long list of sunscreen filters, as well as details about them, are from Skinacea. I'm keeping a copy on my site because things on the internet aren't very permanent, and we absolutely need this valuable resource!