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How do heat protectants for hair work? A chemistry expert explains

<a href="https://theconversation.com/profiles/daniel-eldridge-1494633">Daniel Eldridge</a>, <a href="https://theconversation.com/institutions/swinburne-university-of-technology-767">Swinburne University of Technology</a> Heat can do amazing things to change your hairstyle. Whether you’re using a curling wand to get ringlets, a flat iron to straighten or a hair dryer to style, it’s primarily the heat from these tools that delivers results. This comes with casualties. While your hair is surprisingly tolerant to heat compared with many other parts of your body, it can still only withstand so much. Heat treatment hair appliances frequently operate at over 150°C, with some reportedly <a href="https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2019.00298/full#B13">reaching</a> <a href="https://www.researchgate.net/publication/289291195_Thermal_degradation_of_hair_I_Effect_of_curling_irons">over 200°C</a>. At these temperatures, your hair can end up fried. Many people use heat protectants, often in the form of sprays, to minimise the damage. So how do these protectants work? To answer that, I first have to explain exactly what heat does to your tresses on the molecular level. <h2>What heat does to your hair</h2> A large proportion of your hair is made up of proteins. There are attractive forces between these proteins, known as hydrogen bonds. These bonds play a big role in dictating the shape of your locks. When you heat up your hair, the total attraction of these hydrogen bonds become weaker, allowing you to more easily re-shape your hair. Then, when it cools back down, these attractions between the proteins are re-established, helping your hair hold its new look until the proteins rediscover their normal structure. The cuticle – the outermost protective layer of your hair – contains overlapping layers of cells that lose integrity when they’re heated, damaging this outer protective layer. Inside that outer layer is the cortex, which is rich in a protein called keratin. Many proteins don’t <a href="https://pubmed.ncbi.nlm.nih.gov/21635854/">hold up structurally</a> after intense heating. Think of cooking an egg – the change you see is a result of the heat altering the proteins in that egg, unravelling them into different shapes and sizes. It’s a <a href="https://library.scconline.org/v049n04/33">similar story</a> when it comes to heating your hair. The proteins in your hair are also susceptible to heat damage, reducing the overall strength and integrity of the hair. Heat can also affect substances called melanin and <a href="https://pubmed.ncbi.nlm.nih.gov/21443842/">tryptophan</a> in your hair, resulting in a change in pigmentation. Heat-damaged hair is <a href="https://pubmed.ncbi.nlm.nih.gov/21635854/">harder to brush</a>. The damage is even more devastating if you use heat styling tools such as <a href="https://labmuffin.com/why-you-should-never-straighten-or-curl-wet-hair/">curling irons or straighteners</a> to <a href="https://library.scconline.org/v062n01/23">heat wet hair</a>, as at the high treatment temperatures, the water soaked up by the fibres can violently evaporate. The result of this is succinctly described by science educator and cosmetic chemist Michelle Wong, also known as <a href="https://labmuffin.com/how-do-heat-protectant-hair-products-work/">Lab Muffin</a>. She notes if you heat wet hair this way, “steam will blast through your hair’s structure”. This steam bubbling or bursting through the hair can <a href="https://pubmed.ncbi.nlm.nih.gov/21443842/">cause substantial damage</a>. It’s worth noting hair dryers don’t concentrate heat in the same way as styling tools such as flat irons or curling wands, but you still need to move the hair dryer around constantly to avoid heat building up in one spot and causing damage. Once heat damage is done, regardless of whether it is severe or mild, the best remaining options are symptom management or a haircut. For all of these reasons, when you’re planning to heat treat your hair, protection is a good idea. <h2>How hair protectants work</h2> When you spray on a hair protectant, many possible key ingredients can go to work. They can have <a href="https://library.scconline.org/v062n01/15">daunting-looking names</a> like polyvinyl pyrrolidone, methacrylates, polyquaterniums, silicones and more. These materials are chosen because they readily stick onto your hair, creating a coating, a bit like this: <figure class="align-center zoomable"><a href="https://images.theconversation.com/files/615002/original/file-20240822-16-beyt90.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img src="https://images.theconversation.com/files/615002/original/file-20240822-16-beyt90.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/615002/original/file-20240822-16-beyt90.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=225&fit=crop&dpr=1 600w, https://images.theconversation.com/files/615002/original/file-20240822-16-beyt90.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=225&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/615002/original/file-20240822-16-beyt90.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=225&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/615002/original/file-20240822-16-beyt90.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=283&fit=crop&dpr=1 754w, https://images.theconversation.com/files/615002/original/file-20240822-16-beyt90.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=283&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/615002/original/file-20240822-16-beyt90.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=283&fit=crop&dpr=3 2262w" alt="A cartoon of coating attached to a strand of hair." /></a><figcaption>Hair protectant applies a coating to your hair. Author provided</figcaption></figure> This coating is a protective layer; it’s like putting an oven mitt on your hands before you handle a hot tray from the oven. To demonstrate, I created these by examining hair under a microscope before and after heat protectant was applied: <figure class="align-center zoomable"><a href="https://images.theconversation.com/files/615001/original/file-20240822-16-s2ufqy.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img src="https://images.theconversation.com/files/615001/original/file-20240822-16-s2ufqy.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/615001/original/file-20240822-16-s2ufqy.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/615001/original/file-20240822-16-s2ufqy.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/615001/original/file-20240822-16-s2ufqy.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/615001/original/file-20240822-16-s2ufqy.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=369&fit=crop&dpr=1 754w, https://images.theconversation.com/files/615001/original/file-20240822-16-s2ufqy.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=369&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/615001/original/file-20240822-16-s2ufqy.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=369&fit=crop&dpr=3 2262w" alt="These high magnification images of untreated hair, and hair sprayed with a heat treatment spray, show what a difference it can make." /></a><figcaption>These high magnification images of untreated hair, and hair sprayed with a heat treatment spray, show how the product coats your hair strands. Author provided</figcaption></figure> Just like an oven mitt, a hair protectant delays the heat penetration, results in less heat getting through, and helps spread out the effect of the heat, a bit like in this image: <figure class="align-center zoomable"><a href="https://images.theconversation.com/files/615003/original/file-20240822-16-tf7xsj.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=1000&fit=clip"><img src="https://images.theconversation.com/files/615003/original/file-20240822-16-tf7xsj.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&fit=clip" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px" srcset="https://images.theconversation.com/files/615003/original/file-20240822-16-tf7xsj.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=600&h=233&fit=crop&dpr=1 600w, https://images.theconversation.com/files/615003/original/file-20240822-16-tf7xsj.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=600&h=233&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/615003/original/file-20240822-16-tf7xsj.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=600&h=233&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/615003/original/file-20240822-16-tf7xsj.jpg?ixlib=rb-4.1.0&q=45&auto=format&w=754&h=293&fit=crop&dpr=1 754w, https://images.theconversation.com/files/615003/original/file-20240822-16-tf7xsj.jpg?ixlib=rb-4.1.0&q=30&auto=format&w=754&h=293&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/615003/original/file-20240822-16-tf7xsj.jpg?ixlib=rb-4.1.0&q=15&auto=format&w=754&h=293&fit=crop&dpr=3 2262w" alt="Cartoon demonstrating the difference between heating unprotected and protected hair" /></a><figcaption>Hair protectant can help spread out the effects of the heat. Author provided</figcaption></figure> <a href="https://library.scconline.org/v049n04/33">This helps</a> prevent moisture loss and damage to both the protective surface cell layer (the cuticle) and the protein structure of the hair cortex. For these barriers to work at their best, these heat-protecting layers need to remain bound to your hair. In other words, they stick on really well. For this reason, continued use can sometimes cause a <a href="https://link.springer.com/article/10.1007/s12221-010-0507-9">buildup</a> which can change the feel and weight of your hair. This buildup is not permanent and can be removed with washing. One final and important note: just like when you use a mitt for the oven, heat does still get through. The only way to prevent heat damage to your hair altogether is to not use heated styling tools.<img style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important;" src="https://counter.theconversation.com/content/233206/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /> <a href="https://theconversation.com/profiles/daniel-eldridge-1494633">Daniel Eldridge</a>, Senior Lecturer in Chemistry, <a href="https://theconversation.com/institutions/swinburne-university-of-technology-767">Swinburne University of Technology</a> Image credits: Shutterstock This article is republished from <a href="https://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/how-do-heat-protectants-for-hair-work-a-chemistry-expert-explains-233206">original article</a>.

Beauty & Style

How to make the perfect pavlova, according to chemistry experts

<a href="https://theconversation.com/profiles/nathan-kilah-599082">Nathan Kilah</a>, <a href="https://theconversation.com/institutions/university-of-tasmania-888">University of Tasmania</a> and <a href="https://theconversation.com/profiles/chloe-taylor-1400788">Chloe Taylor</a>, <a href="https://theconversation.com/institutions/university-of-tasmania-888">University of Tasmania</a> The pavlova is a summer icon; just a few simple ingredients can be transformed into a beautifully flavoured and textured dessert. But despite its simplicity, there’s a surprising amount of chemistry involved in making a pavlova. Knowing what’s happening in each step is a sure-fire way to make yours a success. So exactly what does it take to make the perfect pavlova? Let us break it down for you. <h2>Egg whites</h2> <a href="https://theconversation.com/eight-cracking-facts-about-eggs-150797">Egg white</a> is basically a mixture of proteins in water. Two of these proteins, ovalbumin and ovomucin, are the key to forming a perfect foamy meringue mixture. Whipping the egg whites agitates the proteins and disrupts their structure, causing them to unfold so the protein’s interior surface is exposed, in a process <a href="https://theconversation.com/sunny-side-up-can-you-really-fry-an-egg-on-the-footpath-on-a-hot-day-172616">known as denaturing</a>. These surfaces then join with one another to trap air bubbles and turn into a stable foam. Egg yolk must be completely removed for this process to work. Yolk is mostly made of fat molecules, which would destabilise the protein network and pop the air bubbles. It only takes a trace amount of fat, or even just a greasy bowl, to disrupt foam formation. You should always whip your egg whites in a clean glass or metal bowl. Plastic bowls are more likely to hold leftover grease. <h2>Sugar</h2> A traditional pavlova uses sugar – a lot of it – to provide texture and flavour. The ratio of sugar to egg white will differ between recipes. The first thing to remember is that adding more sugar will give you a drier and crispier texture, whereas less sugar will lead to a softer and chewier pavlova that won’t keep as long. The second thing is the size of the sugar crystals. The larger they are, the longer they’ll need to be whipped to dissolve, and the greater the chance you will overwork the proteins in your meringue. Powdered icing sugar (not icing mixture) is preferable to caster or granulated sugar. If you do happen to overbeat your meringue (which may end up looking clumpy and watery) you can try to save it by adding another egg white. <h2>Acid</h2> Many pavlova recipes call for adding cream of tartar or vinegar. Cream of tartar is also known as potassium hydrogen tartrate, which you may have seen in the form of crystals at the <a href="https://theconversation.com/louis-pasteurs-scientific-discoveries-in-the-19th-century-revolutionized-medicine-and-continue-to-save-the-lives-of-millions-today-191395">bottom of a wine glass</a>. These acids act as a stabilising agent for the meringue by aiding in the unfolding of the egg white proteins. More isn’t always better, though. Using too much stabiliser can affect the taste and texture, so use it sparingly. <h2>Heat</h2> Cooking a pavlova requires a very slow oven for specific chemical reasons. Namely, egg white proteins gel at temperatures above 60°C, setting the meringue. At higher temperatures a chemical reaction known as the <a href="https://theconversation.com/kitchen-science-from-sizzling-brisket-to-fresh-baked-bread-the-chemical-reaction-that-makes-our-favourite-foods-taste-so-good-58577">Maillard reaction</a> takes place in which proteins and sugars react to form new flavourful compounds. We can thank the Maillard reaction for many delicious foods including <a href="https://theconversation.com/brewing-a-great-cup-of-coffee-depends-on-chemistry-and-physics-84473">roasted coffee</a>, toast and <a href="https://theconversation.com/what-makes-smoky-charred-barbecue-taste-so-good-the-chemistry-of-cooking-over-an-open-flame-184206">seared steak</a>. However, excessive Maillard reactions are undesirable for a pavlova. An oven that’s too hot will turn your meringue brown and give it a “caramelised” flavour. Recipes calling for pavlova to be left in the oven overnight may actually overcook it. At the same time, you don’t want to accidentally undercook your pavlova – especially since uncooked eggs are often responsible for <a href="https://theconversation.com/how-to-avoid-food-borne-illness-a-nutritionist-explains-153185">food poisoning</a>. To kill dangerous bacteria, including salmonella, the pavlova’s spongy centre must reach <a href="https://foodsafety.asn.au/eggs/">temperatures above 72°C</a>. An alternative is to use pasteurised egg whites, which are briefly heated to a very high temperature to kill any pathogens. But this processing may also affect the egg white’s whippability. <h2>Substitute ingredients</h2> People love pavlova, and nobody should have to miss out. Luckily they don’t have to. If you want to <a href="https://theconversation.com/a-taste-for-sweet-an-anthropologist-explains-the-evolutionary-origins-of-why-youre-programmed-to-love-sugar-173197">limit your sugar intake</a>, you can make your meringue using sweeteners such as <a href="https://theconversation.com/whats-the-difference-between-sugar-other-natural-sweeteners-and-artificial-sweeteners-a-food-chemist-explains-sweet-science-172571">powdered erythritol or monk fruit</a>. But, if you do, you may want to add some extra stabiliser such as cornflour, arrowroot starch, or a pinch of xanthan gum to maintain the classic texture. Also, if you want a vegan pavlova, you can turn to the chickpea instead of the chicken! <a href="https://review.jove.com/t/56305/composition-properties-aquafaba-water-recovered-from-commercially">Aquafaba</a> – the water collected from tinned or soaked beans – contains proteins and carbohydrates that give it emulsifying, foaming and even thickening properties. Egg-free pavlova recipes typically replace one egg white with about two tablespoons of aquafaba. And for those of you who don’t do gluten, pavlova can easily be made <a href="https://theconversation.com/gluten-free-diet-is-expensive-socially-challenging-for-those-with-celiac-disease-and-wheat-allergy-155861">gluten-free</a> by using certain stabilising agents. All that’s left is to get creative with your toppings and decide what to do with those leftover yolks!<img style="border: none !important; box-shadow: none !important; margin: 0 !important; max-height: 1px !important; max-width: 1px !important; min-height: 1px !important; min-width: 1px !important; opacity: 0 !important; outline: none !important; padding: 0 !important;" src="https://counter.theconversation.com/content/196485/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1" /> <a href="https://theconversation.com/profiles/nathan-kilah-599082">Nathan Kilah</a>, Senior Lecturer in Chemistry, <a href="https://theconversation.com/institutions/university-of-tasmania-888">University of Tasmania</a> and <a href="https://theconversation.com/profiles/chloe-taylor-1400788">Chloe Taylor</a>, Research Fellow - PhD candidate, <a href="https://theconversation.com/institutions/university-of-tasmania-888">University of Tasmania</a> Image credits: Getty Images This article is republished from <a href="https://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/how-to-make-the-perfect-pavlova-according-to-chemistry-experts-196485">original article</a>.

Food & Wine

Here’s the science behind your perm

The perm, or permanent wave, has seen a <a href="https://www.elle.com/uk/beauty/hair/a21093906/perm-hairstyle/" target="_blank" rel="noopener">resurgence</a> recently, with the likes of Emma Stone, Selena Gomez, Celine Dion and Naomi Campbell among those embracing their curls over the past several years. But, unlike its 80’s predecessor, the modern perm is more customisable, with everything from spiral coils to wavy hair on the table. Though many of us would have a basic understanding of the process, where rollers and rods are used to take your locks from straight to curled, the way this happens relies on some pretty cool chemistry that takes place in three stages. It comes down to proteins Hair is mostly made up of a fibrous protein called keratin, or more specifically alpha-keratin, which is itself mostly made up of several amino acids: alanine, leucine, arginine and cysteine. This protein is found in everything from our skin and nails to wool and rhinoceros horns, but these wildly differ in strength based on how many groups of two or more cysteines (called residues) are in their structure. These residues are connected to each other by disulfide bonds - two sulfur atoms - which help increase the strength and toughness of the keratin. The more cysteine residues and disulfide bonds there are, the stronger the protein is. <img src="https://oversixtydev.blob.core.windows.net/media/2022/07/perm-science1.jpg" alt="" width="1280" height="720" /> Two sulfur atoms form a bridge between the keratin proteins that make up the majority of your hair’s structure, and it’s this bridge that is altered when you get a perm. Image: Mlpatton (Wikimedia) When these bonds are all parallel to each other, you get straight hair. The process of creating a perm (or permanent wave) then changes how these bonds line up in three steps. The first step will see your stylist apply a substance, usually ammonium thioglycolate or ‘thio’, to break some of these bonds and weaken others, meaning that the proteins in your hair aren’t as strong. For textured hair, this also works to remove the natural curl in your hair. When the rods and rollers are placed in your hair, the proteins can shift position in relation to each other so that they’re no longer parallel. <img src="https://oversixtydev.blob.core.windows.net/media/2022/07/perm-science2.jpg" alt="" width="1280" height="720" /> Getting a perm involves some pretty cool chemistry that sees the structure of your hair change. Image: Professor Richard Payne (The University of Sydney) To set the hair in its new, curly shape, neutraliser (often a dilute solution of hydrogen peroxide) is added. This restores the disulfide bonds between the proteins and locks in your curls. Why doesn’t a perm last forever? Though getting a perm involves breaking and shifting chemical bonds, it isn’t a permanent change. Perms generally last <a href="https://www.healthline.com/health/beauty-skin-care/how-long-does-a-perm-last#cost" target="_blank" rel="noopener">three to six months</a>, depending on your hair type and how you look after it. Your curls might be set but they can be broken and more prone to frizz from chlorinated water, sweat and humidity, Brushing with your standard brush can also cause your waves to disappear, as the disulfide bonds between the proteins in your hair are realigned when you comb through it. Nourishing your hair with protein masks or protein treatments can help your perm last longer, as can avoiding heat styling, reducing how often you wash your hair, and opting for deep conditioning products. Image: Getty Images

Beauty & Style

School pal reveals William and Kate’s intense “chemistry”

The Duke and Duchess of Cambridge’s relationship, from its inception, has been watched by eyes across the world. While the couple held hands and said their marriage vows in front of millions, we’ve also been able to watch their three children grow while they diligently carry out their royal duties. It seems their entire love story has played out before our eyes, however only a select few are privy to their relationship origins at St Andrews. <img style="width: 500px; height: 281.25px;" src="https://oversixtydev.blob.core.windows.net/media/7841192/kate-william-3.jpg" alt="" data-udi="umb://media/19f2d7b5b8ec41ea9394e202978639fe" /> The royal pair’s former classmate Laura Warshauer has revealed what really happened during the first few times Kate and Will met. Telling PEOPLE, she revealed the couple "definitely had chemistry". "Whenever Kate was in the room, Will was obviously paying attention to her," she said. She went on to reveal just how deep their spark went. "When we'd be sitting at lunch in the dining hall and the two of them would be talking, it was amazing to see how natural it was, how they had so much to say to each other. "Looking back, there were all these small moments—certainly moments where I was like, 'Wow, this could really be something.'" William and Kate recently celebrated their 10 year wedding anniversary, after being wed in a royal spectacle at Westminster Abbey in April 2011. <img style="width: 500px; height: 281.25px;" src="https://oversixtydev.blob.core.windows.net/media/7841193/kate-william.jpg" alt="" data-udi="umb://media/0256be85a33c49488766524e854651f3" /> The pair have known each other for many years however, with both of them first meeting in 2001 while both attending St Andrews in Scotland. Kate has said previously of her first meeting with William: "I actually think I went bright red when I met you and sort of scuttled off, feeling very shy about meeting you." <img style="width: 500px; height: 281.25px;" src="https://oversixtydev.blob.core.windows.net/media/7841190/kate-william-1.jpg" alt="" data-udi="umb://media/ff247369c8be4ccda8d49868cc47fbbb" /> They share three children, Prince George, eight, Princess Charlotte, six and Prince Louis, three. Images: Instagram

Relationships

Service pup dons safety “doggles” in chemistry lab

Occupational health and safety is hugely important in every workplace and classroom – even if you’re a dog, it seems. A goggle-wearing dog has become an online sensation after a student at California Polytechnic University shared a snap of the safety-conscious pooch on Twitter. <blockquote class="twitter-tweet"> One of my teammates has a dog in her Chem lab.. he's also required to wear goggles during lab <a href="https://t.co/Wqfrm7oIhW">pic.twitter.com/Wqfrm7oIhW</a> — Tara (@tarahoward75) <a href="https://twitter.com/tarahoward75/status/858373649442586624">April 29, 2017</a></blockquote> The service dog’s adorable adherence to the lab’s safety regulations have won him tens of thousands of fans, with the tweet shared almost 40,000 times and receiving just under 110,000 likes at the time of writing.

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