Video: Why pH matters for AHAs and acids in skincare

Video: Why pH matters for AHAs and acids in skincare

I’ve been a little frustrated with what scientific concepts I can get through in words and crudely drawn illustrations on this here blog. When I teach at my day job, I do a lot of hand-waving, emphatic underlining, symbolic gesturing and smashing together of whiteboard markers, and not having the ability to show movement sometimes feels a bit like I …

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Should You Be Avoiding Parabens? The Science

Should You Be Avoiding Parabens? The Science

Much like “organic” and “all-natural”, “paraben-free” is one of those phrases you’ll see displayed prominently on increasing numbers of skincare and beauty products. What are parabens, what health effects do they have, and should you be avoiding them? Here’s the science behind the marketing.

(I’ve written a much simpler rundown of parabens here, if you want a quicker overview.)

 

What Are Parabens?

Parabens are a family of preservatives commonly used to control the growth of microbes in cosmetics, toiletries, food and pharmaceuticals. They are esters of para-hydroxybenzoic acid, a naturally occurring chemical found in many fruits and plants. Their chemical structures and actions are very similar, with the “R” group changing as shown below.

Paraben Science: Should You Avoid Them in Your Products?

The most commonly used parabens are methylparaben, ethylparaben, propylparaben and butylparaben, although many others (isopropyl-, isobutyl-, pentyl-, phenyl-, benzyl-) have been used in products as well. Different parabens work best under different conditions and act against different microbes, so you’ll often see them used in combination to enhance the preservative effect.

Parabens were developed in the 1920s and these days, they’re the most widely used preservatives in cosmetics, appearing in over 85% of products. Parabens are popular for good reason: they’re inexpensive, effective in very small amounts, work well in most products, and act against a wide range of nasty microbes. They have a very long record (almost 100 years) of safe use. The only reliably linked harmful health effect is allergy, which occurs in a tiny fraction of people, and it’s often only a problem on broken skin.

Why Do Parabens Have a Bad Reputation?

Despite all these advantages, parabens have become well known as a “nasty” in the last 10 years. This came about when a few studies appeared which led people to question whether parabens were really as safe as they seemed:

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Skincare Products I Hate and Do Not Recommend

Skincare Products I Hate and Do Not Recommend

I’ve done a lot of posts on skincare products I love… now, for something a bit different, here are some that I really hate and would only recommend to people I don’t like. So if I ever recommend these to you… it’s not me, it’s you. I just don’t see our relationship working out.

Skincare Products I Hate and Do Not Recommend

Coffee Scrubs

Coffee scrubs are made from coffee grounds, which is literally the stuff you chuck into the bin after making coffee. Now I’m sure there’s a little bit of work involved in making sure it doesn’t mould away in the packet, but essentially you’re buying rubbish at $30 for a small bag.

How can they charge this much, you ask? Well, it’s because they usually claim to get rid of cellulite. This is a bald-faced lie, because apart from the fact that you can’t actually get rid of cellulite, one application of the amount of caffeine required to make cellulite look a little better equates to 2.1 kg of coffee grounds, left on your skin for hours. Any improvement you get is probably mostly a combination of massage, exfoliation and placebo, which really shouldn’t cost that much.

Coffee scrubs are also messy as hell – unlike sugar and salt scrubs, they don’t dissolve in water so gritty black specks will lurk in unexpected places forever. I’m still finding bits of coffee grounds under my soap despite rinsing my entire shower down with vinegar the one time I tried one.

I suppose there’s nothing really harmful about coffee scrubs, really. What pisses me off is mostly just the SHEER AUDACITY of charging so much for a product that’s worse than salt mixed with a bit of oil (about $1.10 a kg, if you shell out for the nice oil). It’s more expensive than a whole bunch of other great exfoliants, and it’s basically bagged up garbage. I wish I’d thought of it.

What you should use instead: Salt + oil, or a leave-on anti-cellulite caffeine cream.

Apricot Scrubs with Shell Bits

First off, physical exfoliation is not the devil. It’s a great thing to use in conjunction with chemical exfoliants. But apricot scrubs containing ground walnut shell… that’s a different matter entirely.

As far as I can tell with my trusty literature review tools, there isn’t any evidence that they cause microtears which harbour bacteria (and I have no idea how that rumour started, but if you know anything about it I’d love to hear from you!), and there are many beneficial products and procedures with harder particles (hello microdermabrasion). But maybe half of the “skincare-naive” people who ask me about their skin problems have this on their bathroom shelf, and they use way too much pressure when scrubbing, and do it way too often (for some reason people feel the need to use it once a day). This sort of treatment usually starts by giving you a nice glow, but it’s unsustainable and quickly leads to sensitive, dehydrated, compromised skin that feels rough and is prone to breakouts. Of course, the obvious thing to do is to use more of the product to get that nice glow back, but it’s a downward spiral from there.

I don’t think St Ives deserves to be sued, but I also wouldn’t lose any sleep if apricot scrubs disappeared. (Also, why are they all called apricot scrubs instead of walnut scrubs?)

Skincare Products I Hate and Do Not Recommend

What to use instead: Any gentler physical exfoliant: konjac sponges, sugar scrubs, cleansing brushes. If you don’t already have an exfoliation routine in place, I’d recommend setting one up.

Soaps for the Face

True or “natural” soaps that is, made from lye or caustic potash and fats or oils. This includes products like African black soap and Castille soap. Soap is bad news for your face for a couple of reasons:

  • It’s impossible for soap to work at a pH lower than around 9.5, which is unfortunate because your face has a pH of 4-6, and high pH will disrupt your skin’s ability to stay intact
  • Soap’s structure (straight tail, small head group) makes it awesome at messing up the proteins in your skin

Some people with tolerant skin will be able to handle soap on their face, and most people can use it on tougher body skin with no big dramas, but a lot of companies that sell soap as facewash go for the “gentle, great for sensitive skin, BECAUSE IT’S NATURAL” angle.

NO.

If your skin is sensitive, soap is not great for it (dehydration, breakouts and roughness galore), and soap isn’t much more natural than gentler cleansing ingredients anyway. Soap is fats and oils which have been reacted to turn it into something else entirely, much like how plastic is made by reacting dead dinosaurs.

What you should use instead: A gentle face cleanser that’s formulated with surfactants made for mildness. Check out this gentle cleansing guide for tips on how to pick a good product and some suggestions.

Hypoallergenic Natural Products Loaded with Essential Oils

On a similar note, the “gentle, great for sensitive skin, BECAUSE IT’S NATURAL” brigade are also really fond of jamming essential oils into products to somehow make them less reactive. Which is entirely the wrong direction to go, because fragrance is one of the things that people with sensitive skin are frequently sensitive to, and guess what – essential oils are fragrant (and plant extracts usually are too). In fact, many synthetic fragrances are just essential oils with some chemicals taken out. That’s why a whole bunch of “natural” skincare products have a list of chemicals at the end of their ingredients, like linalool, benzyl alcohol, geraniol and coumarin – these ingredients known to cause allergies in susceptible people are usually hidden in essential oils and plant extracts, but EU regulations require that they be listed.

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What is hyaluronic acid and how does it work in skincare and makeup?

What is hyaluronic acid and how does it work?

What Is Hyaluronic Acid?

Hyaluronic acid (HA), along with its cousin sodium hyaluronate, is an immensely popular ingredient in skincare and makeup. It’s also naturally found in the body. Most of it dwells in the extracellular matrix, the scaffold which holds up the cells of your skin. Hyaluronic acid is found in both the epidermis and the deeper dermis, where it’s important in hydration, metabolic processes, skin repair, and protection against free radical and UV damage.

 

What is hyaluronic acid and how does it work?

 

Hyaluronic acid is a glycosaminoglycan, a class of chemicals that can hold onto water very efficiently, due to its very polar nature. 1 gram of hyaluronic acid can hold onto 6 litres of water – that’s 6000%! Hyaluronic acid keeps skin firm and plump this way. It’s been thought that decreased hyaluronic acid levels led to the thinner and drier look of aged skin. However, the research currently suggests that the amount of hyaluronic acid in the skin doesn’t actually decrease with age, but it does redistribute with both natural and environmentally-induced skin aging.

What Does Hyaluronic Acid Do in Skincare?

In skincare, hyaluronic acid is mostly used for its incredible ability to hold onto moisture: it’s included in moisturisers and serums as a humectant ingredient. Humectants hydrate the skin, and since one of the effects of dehydrated skin is fine lines and wrinkles, this can make your skin look dramatically younger and less tired. Another popular and cheaper humectant moisturiser is glycerin, but glycerin can feel sticky and heavy. Hyaluronic acid is frequently combined with glycerin to make it feel lighter on the skin.

The hyaluronic acid used in skincare isn’t all the same. It’s usually divided into different sizes: there’s high molecular weight hyaluronic acid, which has a larger molecular size, and low molecular weight hyaluronic acid, which is formed by chopping it into smaller fragments. “Sodium hyaluronate” usually indicates smaller fragments than “hyaluronic acid”, but even within those names there are a range of molecular sizes. The main significance of the different sizes is that smaller molecules are able to penetrate the skin better than larger molecules, which means that low molecular weight hyaluronic acid can hydrate deeper than high molecular weight hyaluronic acid, which holds onto water at the surface of the skin.

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All About Bee Venom and Honey in Skincare

All About Bee Venom and Honey in Skincare

Honey and bee venom have been used in folk medicine for thousands of years, but they’ve made a recent resurgence in skincare. Here’s the science behind these ingredients. Honey in Skincare Honey is formed from nectar and pollen by bees through a process of partial digestion (don’t think too hard about it if you want to enjoy honey ever again). …

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All About Cleansing & How to Choose a Gentle Cleanser

What Makes a Gentle Cleanser? All About Gentle Cleansing

Gone are the days of harsh cleansers that dried out your skin – everyone’s getting into gentle cleansers! What’s the science behind gentle cleansing, and how do you pick a gentle cleanser? Here’s the scientific background behind this skin-loving trend!

Want more about the science behind choosing and using the right cleansers, moisturiser and sunscreen for your skin? Check out The Lab Muffin Guide to Basic Skincare!

How Cleansing Damages Your Skin

Cleansing is the most damaging thing you do to your skin on a daily basis, but unfortunately it’s necessary to get rid of all the dirt, makeup, oil and sunscreen you’ve accumulated on your skin over the course of the day. These unwanted substances won’t come off with water though! That’s why cleansers usually contain surfactants, magical chemicals which can help the grime dissolve in water and wash away.

All About Cleansing & How to Choose a Gentle Cleanser

Surfactants are the key ingredients in pretty much every single cleanser: foaming cleansers, soaps, body washes, cleansing balms, cleansing oils and micellar water. In fact, the only common surfactant-free cleansing methods I can think of are oil cleansing and using a cloth with just water. (I wrote about how surfactants are in everything in this post on The Toast a couple of years ago).

As amazing and useful as surfactants are at lifting grime, they’re not always good for your skin. The outer layer of your skin (the stratum corneum or SC) consists of dead, protein-rich skin cells filled with water-binding chemicals (your natural moisturising factor or NMF), surrounded by carefully arranged oily lipids (mostly ceramides, cholesterol and fatty acids). It looks a lot like a brick wall, with skin cell bricks and lipid mortar. Together, these form a barrier against water evaporating from the skin into the environment, and against external irritants entering your skin.

All About Cleansing & How to Choose a Gentle Cleanser

When the SC’s structure is disturbed, skin becomes dry, itchy, flaky, red and irritated. Luckily, the SC is pretty hardy and holds up well against most things… but unfortunately, surfactants are VERY good at messing things up! Here’s what a harsh cleanser does:

Removes important stratum corneum components

Surfactants are amazing at removing grime, but they can’t tell the difference between the chemicals that make up your skin and the chemicals that aren’t meant to be there. Surfactants are good at removing lipids (particularly cholesterol) from your SC, which messes up its structure and makes it more susceptible to water loss. They also remove proteins and NMF components from your skin, meaning it won’t be able to hold onto water as effectively. This all leads to dry, dehydrated skin.

Remains in the skin, causing irritation and disruption

After cleansing, most of the surfactant gets rinsed off, but unfortunately not all of it. Some surfactant molecules will bind to proteins in the skin, causing them to denature (change shape) and swell.  The more swelling, the greater the irritation. (Interestingly, this interaction with proteins is probably a bigger contributor to the “tight” feeling after cleansing than the loss of oils!) Additionally, surfactants can remain in the lipid “mortar” of the SC, changing its structure. Together, these effects lead to a compromised SC that’s prone to letting water escape and irritants enter.

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Free Acid Calculator for Exfoliants at Specific pH Levels

Free Acid Calculator for pH and Exfoliants

Since writing this post on the influence of pH on exfoliating acid skincare ingredients, I’ve had a lot of questions on how much active free acid there is in specific formulations. The calculation is a bit fiddly to do every time, so I’ve developed an easy spreadsheet to help you predict the free acid content for a product, if you know the amount of the acid ingredient in it, and its pH. This might also be useful if you’re into making your own acid products, or messing around with the strengths of pre-made products.

Free Acid Calculator for pH and Exfoliants

Refresher on Acids and pH

pH is a measure of how acidic or basic something is – a lower pH is more acidic, which means there’s a higher concentration of H+ ions.

AHAs and BHAs (alpha and beta hydroxy acids) are common exfoliating ingredients. They’re acids, which means they can exist in two forms:

  • as the free acid, which means it has no charge
  • as the ionised or dissociated form, which means it’s lost a H+ and it has a negative charge (this is also called its conjugate base)

The two forms can interconvert. Here’s what they look like for glycolic acid:

The ionised form has a difficult time getting through skin’s oily lipid layer and into the skin where it can act. The free acid form is a lot more oil-soluble, so it penetrates a lot more easily. (In some circumstances, if the ionised acid is non-polar enough, it can still penetrate through skin.)

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Do Coffee Scrubs Work Against Cellulite?

Do Coffee Scrubs Work Against Cellulite?

Coffee scrubs are making a big comeback. With brands like Frank claiming that the caffeine in coffee scrubs can reduce cellulite, it sounds too good to be true. So are messy coffee scrubs worth it? What is Cellulite? Cellulite, also called lipodystrophy, is a change in how the fat under your skin is shaped, making it look lumpy or dimply …

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