Should you avoid aluminium in deodorants? The science (with video)

I’ve recently been approached by several natural deodorant companies to talk about the health risks of aluminium-containing antiperspirants. As much as I’d like that sweet sweet cheque… I can’t. Because the science just isn’t there. So instead, I’m going to debunk the aluminium scaremongering. (Note to deodorant companies: There are valid reasons to switch to natural deodorants. Aluminium ingredients can …

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Chemical Exfoliants as Deodorant? The Science of Smelly Armpits

deodorant

As a dedicated skincare addict, I own quite a few never-ending bottles of exfoliating acid toners that I can’t really use up fast enough. They’ve been sitting around going dusty, and I was prepared to gift them to my grandchildren one day. Enter Tracy Robey, of fanserviced-b. Tracy, a longstanding member of the online skincare community, has kindly performed some …

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How Do Bath Bombs Work? The Science (With Video)

lush-golden-wonder

lush-golden-wonder

Bath bombs are awesome balls of fizzy goodness, with some interesting science behind them! They were invented in 1989 by Mo Constantine, one of Lush’s founders. Bath bombs contain the chemical sodium bicarbonate, also known as baking soda, as their key ingredient.

This is the text version – scroll down for the video!

Some of you might remember that baking soda isn’t good for your skin because it’s a base, with a high pH. High pH (alkaline or basic) products disturb the skin’s acid mantle, which protects your living tissue from the environment, particularly bacteria, like acne-causing Propionibacterium acnes.

But don’t fret! The second key ingredient in a bath bomb is a solid acid, such as citric acid or tartaric acid (cream of tartar). This lowers the pH by reacting with the baking soda when water is added to the mixture. Unless the maker of the bath bombs has really messed up their proportions, the final pH should be reasonably neutral. Until the water dissolves the acid and baking soda and allows them to mix at a microscopic level, nothing happens.

Aside from neutralisation, the acid + base reaction with sodium carbonate also produces tiny bubbles of carbon dioxide gas, which is what causes the fizzing:

Citric acid + sodium bicarbonate → sodium citrate + water + carbon dioxide

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Gift Ideas for a Good Cause From The Body Shop

Gift Ideas for a Good Cause From The Body Shop

Christmas is always a stressful time of year, with so much event planning and food prep and running around before all the shops close for public holidays. That’s why I’m a big fan of gift sets, and The Body Shop always has a great selection at various price points. I’m not a huge fan of unbridled capitalism, but I also …

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Gradual Tanners: Bondi Sands, Dove, Fake Bake & St Tropez review

gradual-tanners

You can’t tan without exposing yourself to wrinkles and melanoma, so fake tan is the way to go if you want to go brown. I’ve recently tried 4 gradual tanners widely available in Australia:

gradual-tanners

  • Bondi Sands Everyday Gradual Tanning Milk
  • Dove Summer Glow Gradual Self Tan Body Lotion (Fair to Medium)
  • St Tropez Gradual Tan Everyday Body Mousse
  • Fake Bake Sport Daily Tan

If you’re not confident in your ability to apply fake tan smoothly, or you’re scared of people asking you why you became a super dark tanned glamazon goddess overnight, then gradual tanners might be for you! These contain a lower percentage of dihydroxyacetone (DHA), the staining ingredient in fake tan, so the tan builds slowly over a few applications. (You can read all about how the dihydroxyacetone in fake tan works in this post.) Here’s how they fared:

Colour

Criteria: Not too orange is pretty much my only criteria. Getting a decent amount of colour after 2 applications is good too.

Results: All 4 were surprisingly comparable. I used a different tanner on each limb, and at the end they all looked pretty much the same. Fake Bake was a touch darker than the rest, and Dove was a touch lighter (Dove also has a Medium to Dark version which I haven’t tried). Dove and Fake Bake were a bit more yellow, while St Tropez and Bondi Sands are a bit more pink/brown, so they’ll look a bit more natural if you don’t have a yellow undertone.

Winner: Bondi Sands and St Tropez for a more natural colour for people without a yellow undertone, Fake Bake if you want a faster result and your skin works well with yellow.

Ease of application

I like my fake tan to be easy to apply in awkward places (middle of the back, especially!). I want it to spread evenly with minimal effort.

Results: Bondi Sands and Fake Bake are runny lotions, Dove is a thicker lotion, and St Tropez is a foam. The foam was by far the easiest to apply, though the runny lotions weren’t that difficult, especially when I started using a mitt. Dove was the hardest to rub in, but again it wasn’t too bad with a mitt.

Winner: St Tropez, though a mitt makes anything possible.

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The Science of How Fake Tan Works

arm-leg-fake-tan

These days we’re all aware that suntans give you both cancer and wrinkles, so fake tan is the colour du jour. This miracle-in-a-can stains the skin brown through an interesting chemical reaction. The outer layer of your skin, made up of dead skin cells, is permanently coloured. The tan wears away as the skin cells come off. Here’s how it works, and whether it’s safe!

The Chemistry of Fake Tan

Fake tan products you find in stores contain 2-5% dihydroxyacetone, which looks like this:

dihydroxyacetone-chemical-structure

It starts off colourless, but it reacts with amino acids (particularly arginine, lysine and histidine) in the skin to form a variety of brown compounds called melanoidins.

amino-acids-dha

It’s actually the same chemical reaction as the one responsible for making food like bread and meat turn brown and delicious when cooked. It’s called the Maillard reaction. For the really intense chem nerds, it proceeds like this with DHA (I got a bit lazy, sorry for the shortcuts):

mechanism-DHA-melanoidins

This forms covalent bonds, which means the skin is permanently stained – water, soap and moisturiser won’t wash it off. The skin starts devloping the tanned colour after 2-3 hours, and the reaction continues for the next 1-3 days. The reaction occurs best at moderately low acidic pHs (3-6), so fake tans tend to come in this skin-friendly range. The extent of the reaction is also influenced by the amount of water around.

Application and Aftercare

DHA only penetrates the very top layer of skin (the stratum corneum), which you may know is dead skin cells. This is why fake tans can’t last longer than about a week – that’s about how long it takes for the stained skin to wear off (that’s why if you look up fake tans that claim to last longer than a week or two, you’ll find tons of grumpy reviews – the skin sheds at a similar rate no matter what product you use!).

This explains all the advice given for making your tan look good and wear off evenly:

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What is clinical strength antiperspirant deodorant?

My go-to antiperspirant deodorant, Nivea Stress Protect, has recently come out with a clinical strength version, and since it’s been a while since I blogged about underarm matters, I thought it was time to revisit the basics of sweat science… What’s the difference between deodorant and antiperspirant? Deodorant targets smell. It usually contains fragrance, and sometimes antibacterials too to kill …

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Anatomicals Australian range – review

Funky British brand Anatomicals recently launched properly in Australia. The brand has been a bestseller on ASOS for a while already, but you can bag them now  in store at Target, Priceline and Chemist Warehouse. I have to admit – I’m a massive sucker for nice smells, cheerful packaging and cheeky marketing. Luckily for me, Anatomicals is reasonably budget-friendly (body …

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