Video: What Does SPF Mean? Is High SPF Sunscreen Better?

Video: What Does SPF Mean? Is High SPF Sunscreen Better?

Here’s a new video that covers what SPF means, and debunks a couple of SPF myths:

  • Why SPF doesn’t mean how many times longer you can stay in the sun
  • Why higher SPF is more effective (and not just 1% more effective)

I’ve talked about the first myth before in this post on SPF and UV index, but I haven’t really talked about the “SPF 50 is only 1% better than SPF 30” myth before, except as an aside in my post on the relationship between SPF and the amount of sunscreen applied. It’s a myth that’s widespread, even amongst dermatologists, according to this open access paper from JAMA Dermatology (DOI: 10.1001/jamadermatol.2016.4924).

I also cover how SPF changes with the amount of sunscreen applied, and other things to consider apart from SPF in the video. Check it out here!

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Video: Antioxidants in Skincare, and Tips for Product Selection

Video: Antioxidants in Skincare, and Tips for Product Selection

I’ve made a new video about antioxidants in skincare – it’s based on this post from a while ago: Antioxidants in Skincare: What Do They Do? In the video, I talk about: What free radicals are How they’re linked to skin damage Where free radicals come from How antioxidants work Which antioxidant ingredients have been studied in clinical trials Tips on …

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What Are Propylene and Butylene Glycol, and Are They Safe?

What are propylene and butylene glycol, and are they safe?

One of the common reader requests I get is for “toxic” ingredient breakdowns, so today I’m looking at two ingredients that are commonly on “avoid” lists: propylene and butylene glycol.

What are propylene and butylene glycol, and are they safe?

What are propylene and butylene glycol?

Glycols in chemistry are ingredients that contain two OH (alcohol) groups. Propylene glycol contains 3 carbon atoms, while butylene glycol is a little larger and contains 4 carbon atoms. In glycols, the alcohol groups are attached to different carbons.

Confusingly, the names “propylene glycol” and “butylene glycol” can refer to several slightly different substances, since there are a few choices of carbon atoms for the OH groups to be attached to.

Propylene glycol usually refers to propane-1,2-diol (formerly known as 1,2-propanediol). The less commonly used propane-1,3-diol is also sometimes called propylene glycol, but usually in cosmetics it’s called “propanediol”. Propanediol is become more popular since propylene glycol’s been on all these watchlists.

What are propylene and butylene glycol, and are they safe?

It’s a similar story for butylene glycol. “Butylene glycol ” usually means butane-1,3-diol, but sometimes it’s also used to refer to the related butane-2,3-diol.

What are propylene and butylene glycol, and are they safe?

What do propylene and butylene glycol do in products?

Alcohol (OH) groups on ingredients usually make them good humectant moisturisers that can hold onto water and keep your skin or hair hydrated. For example, glycerin has almost the same structure as propylene glycol, but with an additional alcohol group. Propylene and butylene glycol are both humectant moisturisers.

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Product Rant: SPF Sunscreen Drops

Product Rant: SPF Sunscreen Drops

Here’s a pet peeve of mine: SPF drops and boosters. Fellow skincare fanatic Hannah (@ms_hannah_e on Instagram) reminded me about them recently, right when I was in a ranty mood, so it fit right in.

Product Rant: SPF Sunscreen Drops

What Are SPF Sunscreen Drops?

SPF Sunscreen Drops are products that you’re supposed to mix into other products to “turn them into sunscreens”. Some examples are:

Why would you use these? Sunscreens often have horrible textures, so why not turn a product you already like into a sunscreen by adding some sunscreen drops into it? Not so fast…this ain’t a rant post for nothing.

Why I Hate Sunscreen Drops

Reason 1: They don’t deliver the protection they suggest

See that SPF number? It looks nice and high… but that’s the protection you’ll get if you apply the undiluted product directly on your skin like a regular sunscreen, with 2 mg of product applied per square centimetre of skin. On my face, that translates to about 3/4 of a quarter teaspoon.

So let’s work out the SPF protection if these sunscreen drops are used as intended.

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Chemical vs Physical Sunscreens: The Science (with video)

Video: Chemical vs Physical Sunscreens: The Science

Video: Chemical vs Physical Sunscreens: The Science

Are chemical or physical sunscreens better? I touched on this in my Sunscreen and Make-up video, but a lot of people have been asking me to talk more about it, so I’ve expanded on the topic in this post, which comes in video form as well!

Click here for the video – scroll down for the blog post “summary” version with references and product recommendations (which is still somehow 1500+ words long…).

What Are Chemical and Physical Sunscreens?

The active ingredients in sunscreens are often divided into two categories:

  • Physical sunscreen ingredients (more correctly known as inorganic sunscreen ingredients) are zinc oxide and titanium dioxide.
  • Chemical sunscreen ingredients (more correctly known as organic sunscreen ingredients) are everything else.

You can have sunscreens containing only organic filters, only inorganic filters, or a combination of both.

Video: Chemical vs Physical Sunscreens: The Science

The reason organic (carbon-based) and inorganic (not carbon-based) is a better classification than chemical/physical is that there’s overlap between how they work. Both types work by absorbing UV and turning it into heat. Inorganic sunscreens also scatter and reflect about 5-10% of the incoming UV, as do some particulate organic sunscreens like Tinosorb M, so really they should be classified as both chemical and physical.

Differences Between Chemical and Physical Sunscreens

The big differences between them that you should consider are:

Protection Level

SPF 50+ is pretty common with both types of sunscreen, but broad spectrum protection (that includes protection against longer wavelengths of UVA) is where there’s a difference.

Organic sunscreens give higher, photostable protection from UVA if you use newer filters like Tinosorbs S and M, and Uvinul A Plus (not yet available in the US). The more common avobenzone gives really high UVA protection, but it breaks down in UV so you have to be diligent about reapplication (although some formulas stabilise avobenzone so it breaks down slower, and you should diligently reapply sunscreen anyway if you’re spending a lot of time in the sun).

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Video: How Much Sunscreen Do You Need For Your Face?

Video: How Much Sunscreen Do You Need For Your Face?

Video: How Much Sunscreen Do You Need For Your Face?

You’ve probably heard that you need 1/4 teaspoon of sunscreen to cover your face. This quantity is calculated from an estimate of people’s face sizes, and the amount of sunscreen they use in SPF testing (2 mg per cm2). Since it’s based on the thickness of sunscreen, a larger face will need more sunscreen, while a smaller face will need less sunscreen. But how much sunscreen would I need?

Because I have an unusually large forehead and a flat-but-wide nose, I didn’t want to use a rough geometric estimate, and opted for a more empirical (and hopefully accurate), fiddlier measurement method instead. I decided to work out my facial surface area by covering my face with paper tape, then taping it onto grid paper and counting the area. Of course, I filmed the process! I then worked out how much sunscreen I needed for my face, and I also worked out how much sunscreen I needed for my neck and decolletage.

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Video: Do Collagen Supplements Work for Wrinkles and Younger Skin?

Video: Do Collagen Supplements Work for Wrinkles and Younger Skin?

Supplements are one of the big new “it” categories in beauty, and collagen supplements are one of the most popular. Oral collagen supplements are supposed to be anti-aging, get rid of wrinkles and plump up skin so it looks younger. What’s the science behind them and do they really work?

I made a video on the topic! In it I talk about the way collagen supplements could theoretically work, and then break down the clinical studies on eating and drinking collagen.

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Mythbusting: Are Vitamin C Serums Bad for You?

Mythbusting: Are Vitamin C Serums Bad for You?

I’ve been asked a lot for my opinion on a recent article on whether vitamin C serums are bad for your skin. In the article, Wendy explains why Oumere will never have a vitamin C serum in their line. She outlines that vitamin C can:

  • Act as a pro-oxidant when it reacts with iron in the air (or iron and copper in cosmetics) via the Fenton reaction, leading to irritation, collagen and elastin breakdown and acne
  • Lead to desensitisation (tachyphylaxis) so if you start using it too young, your skin won’t respond later on

Let’s take a look at both of these arguments.

Is Vitamin C Pro-oxidant?

While in some circumstances vitamin C can act as a pro-oxidant after it reacts with metals and potentially lead to collagen destruction, vitamin C is also known to have effects that are the exact opposite:

  • Vitamin C on its own is a potent antioxidant that soaks up free radicals and prevents the oxidative damage that results from UV light and other environmental stressors, as well as normal biological processes
  • Vitamin C is an essential cofactor that’s required for enzymes that crosslink and stabilise collagen (prolyl and lysyl hydroxylase)

Mythbusting: Are Vitamin C Serums Bad for You?

So how do we tell which of these actions, pro-oxidant or antioxidant, wins out? Science, of course! More specifically, we have quite a lot of clinical trials on vitamin C where vitamin C serums are applied to actual human skin, and its effect is measured. Vitamin C is one of THE best researched skincare ingredients.

None of the clinical trials on topical vitamin C (that’s vitamin C applied to the skin) found a decrease in collagen. In fact, a whole bunch of studies found that vitamin C increased collagen. In these studies, the volunteers were also exposed to air pollution and other cosmetic products, which were proposed to be the sources of metals that would cause a pro-oxidant effect in the article. Clearly the antioxidant effect is winning.

Related Post: Antioxidants in Skincare: What Do They Do?

Studies where vitamin C increased collagen:

Most studies on vitamin C measure its effect on photodamage. These studies generally measure the effect of vitamin C on wrinkles. While this isn’t a direct measure of collagen, lack of collagen causes deeper wrinkles, so if vitamin C was having a pro-oxidant effect you’d see a worsening of photodamage (which is actually caused partially by increased oxidation). In these studies, vitamin C improved photodamage:

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