The science of haircare

A few weeks ago I instigated a twitter conversation around shampoos after going to see the launch of a new range from L’Oreal, which I believe is the beginning of a revolution in the mass haircare market. The range is SLS and silicone free (of which you can read more about here) but that led to a lot of questions from people asking ‘what does that actually mean?’ and ‘why is that good for my hair?’ Back in the day I worked for a professional haircare brand and started studying for a qualification in the science of hair and skin; this has given me a lot of knowledge and understanding of beauty products and what claims can actually be substantiated. There are so many myths and miscontrued pieces of information out in the social space, so this hopefully clears up some of those and answers some burining questions.

What is an SLS free shampoo?
Sodium Lauryl Sulfate (or SLS) is a chemical ingredient used in lots of different cleansing products such as shampoo, shower gel and face wash. It’s this agent that actually gets rid of the oil, grease and dirt from hair and skin by grabbing onto it so it can be washed away with water. Although this is used in the majority of products you can buy on the high street, it can actually be harmful to sensitive skin and cause problems – particularly by stripping away too much oil/moisture and aggravating conditions like eczema and psorasis. Even if you don’t normally have sensitive skin, excessive use of products containing SLS can cause itchy, flaky or dry skin. For the majority of us it won’t cause a problem to use products containing this ingredient, but if you do suffer with an itchy scalp or really dry limbs this may be a good place to start investigating. It’s become a trend of late to claim you’re SLS free as brands become aware that consumers are understanding the science behind their ingredients; this isn’t a reason to panic though as for the majority of us you can get away with using SLSs without a care in the world.

My SLS free shampoo doesn’t lather as much – is it cleaning my hair?
Yes, totally, 100%. We’ve all been molded into believing that a good shampoo is one which gives off a really rich, creamy, foamy lather. However, this isn’t actually a sign of a good shampoo as all the product is doing is capturing air rather than grabbing and removing dirt. The cheaper ingredients are the ones that foam the most, meaning it’s normal for your bottle of £2.99 shampoo to lather like a foam party in Ibiza, but your £15 bottle from the hairdressers to not. We’re so used to doing the ‘lather, rinse, repeat’ routine that it takes a while to get used to ‘wash, rinse, sit back’ instead.

I’ve heard silicones are bad – why?
Many shampoos and conditioners contain silicones which sit on the surface of hair and create a smooth, silky and shiny finish. This is great for a week or so, but as you continue to use the product the silicone just builds up and up until you’re left with a coating of silicone all over your head. This will start to weigh down your barnet over time, leaving you with limp and lifeless hair that you can’t do much with. The silicone molecule is too large to be absorbed into the hair so it’s purely a superficial ingredient to make hair look pretty, albeit temporarily. The problem worsens when you change shampoos and it takes a while to strip the silicone to reveal the hair underneath – so many people think the shampoo isn’t working and return to their silicone-heavy brand and the cycle starts all over again. The key is to firstly stay away from as many silicone heavy brands as possible, but also to use a claryfying shampoo every 2-3 weeks to strip away any build up and reveal a healthy swishy head of hair underneath.

I’ve heard products claim to improve the health of my hair – can they?
In a word, no. Hair is dead. Once it pops out the top of your head there’s nothing you can do to actually improve the health of your hair, you can only improve the appearance. You can coat it in good stuff, create an illusion of shine, volumise it, fiddle with it and style it within an inch of its life, but effectively it’s as dead as a dodo. When shopping for products be very careful because there are certain legalities around what you can and can’t say – when I was working in NPD at a professional hair care brand I spend my life putting the word ‘help’ in front of every sentence that came out of the PR department! You can help prevent breakage or damage to hair by coating it or using products full of strengthening ingredients, but on the whole a lot of the campaigns I see on a daily basis are somewhat misleading – be careful what you believe.

This is a start to the discussion around haircare, skincare and whatever else you want to know. I’m more than happy to answer questions or follow up on this post with future ones, depending on what you’re burning to ask! Just add a question in the comments section below and I’ll be back with my science hat on shortly…



  1. Katy
    February 13, 2012 / 1:08 pm

    What a fab post, totally clear & easy to understand, something which is generally lacking elsewhere. I have a sensitive very dry scalp & really struggle to find a decent shampoo. This post will definitely make it easier. Thank you!

  2. sugarpuffish
    February 13, 2012 / 2:41 pm

    Every product I use on my body & face is natural & free from SLS, parabens, petrochemicals but the one area I struggle with is haircare. I've tried them all high street, salon and handmade. I find SLS free shampoos dry out my hair, I follow with conditioners but I just can't make it work for me. Do you have any ideas why this happens?

  3. Hollie
    February 13, 2012 / 3:31 pm

    loved reading this post. My mum is a hairdresser and she gets so frustrated with constantly having to tell people that no products can't actively repair hair follicles!Hollie

  4. RuBee
    February 13, 2012 / 4:52 pm

    This is a great post. I've been wanting to know answers to questions like these for some time and you explained it all so well. Thank you x

  5. Maya
    February 13, 2012 / 5:17 pm

    Very clear and informative stuff…Thank you very much!

  6. Emily Jayne
    February 13, 2012 / 5:51 pm

    Thanks for this – it's really interesting and informative.The other reason that I've been told to avoid silicone products is that high-heat styling tools such as GHDs can actually irreparibly bond the silicone to the hair shaft, making it look dull and 'synthetic looking' over time. Is this true?

  7. Make Up By Sarah Leanne
    February 13, 2012 / 7:42 pm

    Great blog post! 🙂 didn't know any of that before! Thank you 🙂 xxx

  8. Amy-louise
    February 14, 2012 / 4:25 pm

    Restorative products can temporarily fill gaps in the cuticle layer of the hair which helps to protect the cortex where the moisture is held. But damage is irreversable 🙁 damn you heat & chemical damage! X

  9. liloo
    February 15, 2012 / 9:50 pm

    I officially love you. Loved every bit of that post, loved loved loved. So much stuff I didn't know and you explained it all in a friendly (and humourous) language too. 'party like a foam party in ibiza' -> bwhahahaahahahahaha :)your tweets from before and now this post has encouraged me more than ever to detox my hair once a month. (I only wash my hair twice a week)As a follow up, anything you would be ready to write about heat damage and hair colour, especially the myths around it, would be absolutely awesome. things like:- can a shampoo really HELP slow the fading of a colour. If not, what can help- this business of washing your hair with just conditioner or something, is that any good?- 5 biggest crimes you are doing to your hair and that you didn't even know- do I need to use a heat protectant if i only use my straightening irons once every 3 months- what's the best form of heat protectant, how to use it? won't too much make the hair greasy and get dirty quickly- what's a normal amount of hair to lose a day? – are we damaging our hair if we rinse it with too much water pressure?- what about this myth of cutting on the full moon to make it grow quicker?- ammonia: is that the same thing as peroxide? – is it true hairdressers would refuse to colour your hair if it's been exposed/treated/coloured with henna before?ok, that's it for now, lol xxliloo/@tsunimee

  10. liloo
    February 15, 2012 / 10:06 pm

    i am scared of permanent colours. I've only used one permanent colour in my life in a packet and i remember it really drying my hair and I was put off by it really. Are the permanent hair colours now en par (is that the expression) with semi permanent, are they substantially more damaging to your hair, or is that a myth as well? – Are you creating build up with years and years of using semi permanent colour on your hair, even if the roots are visible and you feel the need to colour it again cos your grey is showing?- Is it ok i re colour every 4 weeks or is that too soon?- why is it that most hair colour ask you not to shampoo your hair before hair colouring? sorry but I can't do that. is that something to do with 'porous' hair (i dont even know what it means, i need a 4year old drawing to understand i think, haha)- this is a silly question, dont laugh. if you're only meant to use conditioner on the ends of your hair, how the hell do you put conditioner if you have short hair?- final question (i am so scared of the answer) I rarely use conditioner on normal basis, as I find my hair doesn't get dirty as often. I don't use heat either on a normal basis, and I let it dry naturally. Am I committing a sin by not using conditioner? I do make an effort when i am going out, i.e when I am not just going to the office.ok. i think that's really it, now x(oopsie) any thoughts you might have would be welcome

  11. senorita carmen
    February 16, 2012 / 12:05 am

    Great post really interesting. I use SLS shampoo and a clarifying shampoo every few weeks. My question is around conditioner: yet to find an SLS version creamy enough for my fine knotty hair. Any recommendations?

  12. London Beauty Queen
    February 19, 2012 / 5:19 pm

    Right, I'm going to try and answer some questions, but others I'll use as the basis of another blog post. Sugarpuffish – I haven't heard of this before as it's really hard for a shampoo to strip hair of moisture (as far as I'm aware.) Maybe your hair needs a deep treatment once a week to repair and impart moisture deep into the hair to help it rejuvinate. Emily Jane – That's a common myth. You should always use a heat protector if you're using hair straighteners and be careful to use a treatment once a week. However, you can't bond silicone using your hair straighteners. This is something that's probably come from people with hair extensions as there can be issues with the bonds, silicone and heat. Liloo – I'll answer all your Qs in another post!

  13. Lisa
    June 8, 2012 / 1:06 pm

    The saviour of the world. Thank you for your treatment of this wonderful subject.Hair Care Beauty

  14. Jade.
    July 4, 2012 / 9:28 pm

    Fab post… Silicones could be a contributing factor to my ridiculously over greasy hair… Or might just be greasy in general… Ew haha Xx

  15. Anna Talks Beauty
    July 30, 2013 / 11:34 am

    Great post, very informative! There is so much talk of sulfate free, silicons etc, it can be quite confusing to know what is good and bad! Thank you and I will certainly be checking for more advice. Anna x

Leave a Reply


Looking for Something?