this test is everywhere testing heat protectants I'm going to pop this onto another receipt let's see if it works there is absolutely no burn it truly works ooh and it's not just influencers we have brands jumping on the bandwagon too but does this test actually work? I had a bunch of receipt paper and a hair straightener so I tested the test it turned out to be way more complicated than I expected hi I'm Michelle chemistry PhD and hair nerd I talk about the science behind beauty products so when there's a weird test going viral I get tagged and so many of you tagged me in these tests I was going to put it in one of my TikTok reaction compilations because it seems like any other dodgy test we have a hair product being tested on something that isn't hair and I wanted to just say that your hair is not a receipt but then some people mentioned this we're testing them on receipts because they turn black when exposed to heat by the way the reason this works is that the receipt reacts in response to heat and that's not a bad point could receipts still tell us which heat protectants work better? I did not know what I was getting into this is Lucy Seitz she's a cosmetologist and her tests are going super viral and I quite like her tests because her approach is kind of scientific we're testing out heat protectants the straightener is at 340 this is without any heat protectant this is nice testing the receipt without any product is called a control and this way you can see if the product is actually doing anything and honestly not enough of these tests use controls Moroccanoil so you can see there is potential here heat protectants are meant to protect hair from heat heat makes the receipt change color and you can see that the receipts are different colors the bits that have more protectant tend to be a bit lighter we do use models in science that's when we test on something that isn't the real thing but it has similarities but if the model is too different then it can be completely useless I go through a bunch of examples in this video so the question is: are these receipts staying lighter because they're more protected from heat? so some people said she wasn't letting it dry enough and bless her she does a video where she shows herself drying it that to me looks like a whole bunch of product dripping off and this is a problem because all this extra stuff can help cool things down especially if it's water so this would not be a fair test maybe it isn't dried properly hair might dry differently from paper because it's in strands it has a much bigger surface area I can't really tell what's going on here I'm going to try this with heat protectant for myself I have my straightener set to 170 which is pretty much the same as what she's got this is no heat protectant probably should have let that dry this is like smoking I think I'll do all of these I'll spray all of these and then let them dry I also put product on the bottom half on the back because the straightener heats up the paper from both sides so that could make it hotter I didn't really think it'd make much difference but why not this is interesting this one is actually already going kind of grey this one has also gone really dark it's like grey as well not really sure what's going on I also applied a bunch of cream products that came in tubes and then it was time for the straightener I've put these roughly in order from lightest to darkest and the lightest ones are the creams and I'm guessing that's because we're putting on a lot more product so having a thick coat of product would also mean any solvent any water for example would just be evaporating a lot slower then if we go down to the darkest these two are actually the ones that don't have water anywhere near the top of the ingredients list so that would also make sense if it's the water but then all of this middle stuff you can sort of see how like the system got a bit dicey around here I'm not really seeing any sort of pattern with the ingredients in these so it might just come down to how much product I sprayed on and how long I left them to dry huge difference if you wait 15 minutes this is definitely a drying thing so maybe what's happening is at 15 minutes there is still enough water in these receipts to cool them down and keep them lighter also bottom half no difference to test whether wet versus dry explains it I dunked and sprayed a bunch of receipts with water then I tested them immediately after 2 minutes 5 minutes and 10 minutes I think it's pretty obvious that water makes a difference water is really powerful it's really good at absorbing heat a little bit of water can do a lot of cooling and paper is good at holding on to water she is not dunking her receipts in but heat protectants do contain humectants which hold onto water and slow it from evaporating with a real product this effect could last longer than 5 minutes I also tested a bunch of receipts 24 hours after applying product on them to make sure they were completely dry I did not expect this obviously the amount I put on wasn't controlled but with the creams it looks like the first day is a little bit lighter than the second day that could be because the first day it's still wet and water is cooling it down but it's really uneven and the difference isn't really that big but with the sprays the second day tests look lighter than the first day and that's really not what should happen if it's just wet something else is going on so it literally just occurred to me that I should triple check the temperature that receipts change color at the start I googled receipt ink temperature and I got this which is from this page and that's similar to a hair straightener the other results didn't have numbers so I just assumed that was in the right ballpark but when I was looking up more about the structure of receipts I ended up on German Wikipedia as you do I found this paper which I fed into Google translate and it says 40 to 80 °C which is way lower than I thought then I tried searching what temperature does thermal paper change colour and I got completely different results because Google is freaking broken 66 60 and then we have a thermal paper company that says it starts to develop color at 60 to 100 and it reaches applicable density I assume that means it is black enough between 70 and 120 Fahrenheit is on the screen for the heathens quick test with boiling water 100 °C I probably should have checked that earlier it looks like there are lots of different types of receipt paper but hair doesn't really get damaged until it gets somewhere near 100 °C so if these receipts are changing color at the lower end say 40 °C then this test is completely useless it's going to change color well before hair gets damaged and it won't tell us anything about good versus bad protectants in other words all of this might have been a massive waste of time and I should really rethink my choices in life the thing is if it does turn out to be 40 °C and I was just making a reel and trying to explain it quickly because algorithm I would say something like this test doesn't work because receipts turn black at 40 degrees that is way too cold to straighten hair and way too cold for heat damage so paper isn't hair this test doesn't tell us anything and I'd probably get a whole bunch of comments saying well that's super obvious how could anyone be dumb enough to think this test was legit? and that's pretty unfair right because sometimes it is obvious but most of the time it just seems obvious because you just heard the answer explained in a really easy to understand way I mean we are this many minutes into the video but I've been working on this for weeks I have a chemistry PhD and most of the time I'm not physically testing things as much but I'm looking up info and the steps are the same analyse the problem work out the right questions to ask find the information and then join everything together if you happened to already know about hair temperatures and receipt temperatures then it might be obvious but that is a really small number of people if you put a battery into water you'll see bubbles and if you know a bit of chemistry then it's really obvious water H2O it's splitting into hydrogen and oxygen gas that's the Hs and the Os but it took scientists ages to work out H2O Cavendish pretty much showed this but then it took another 25 years and tons of experiments mostly from Lavoisier before most scientists agreed he had to invent his own equipment absolute mad lad but because we got spoonfed this at school then to us it's like water is H2O duh I never have time to explain the whole process in my vertical videos like how the sausages are made so this is nice because you get to see the whole journey or at least that's what I'm telling myself because if it does turn out to be 40 °C next experiment to work out of receipts change color at 40 or closer to 100 °C or if they are all really different I cut up different receipts and stuck them together I boiled some water and started dipping them in at different temperatures water is fantastic at keeping temperatures stable we love water on this channel I tried a few different setups because we have another weird thing happening the bits where the sticky tape was stuck didn't go dark what is going on here? after 3 hours we had a clear result most receipts turned black around 95 °C so at least the temperatures for the test make sense yay we did it I need to lie down like and subscribe if you like watching me struggle so at this point we've explained some of what we're seeing some products work because there is a bunch of water soaking up the heat some products have more water the bits that have more product will also have more water products that came in tubes worked really well because they apply more thickly than with a spray there was also a big difference with that first product I tested after it had time to dry down a bit blow drying probably can't completely get rid of water so this water is evaporating you can see the steam and that's cooling down the receipt so this already shows that this test isn't that good water is a terrible heat protectant it's actually not good for hair water soaks into the middle of the hair and then when you heat it quickly it all evaporates and sort of like popcorn it expands inside the hair and just really damages it from the inside and I mean a metre of air is a fantastic heat protectant but that's because your receipt slash the hair they are not being heated and that was the whole reason you were using a hair straightener in the first place but we also have a whole bunch of observations that this hypothesis doesn't explain some products are working just way too well when will water evaporates hydrogen bonds are breaking and they're absorbing a whole bunch of heat if you dunk a receipt in water that is going to stay cooler than a receipt that just has a really thin layer of stuff on it so why is this thin spray keeping it so white we also have the sticky tape receipts staying white and also the receipts turning grey immediately right after I sprayed them and I really didn't expect this to happen because I didn't see this happening in anyone else's videos I wish I filmed this when it dawned on me because this was the moment so you'll just have to imagine my mind exploding when I started going through her footage again it's really subtle and it's a bit hard to tell if some of them are actually grey or if it's just wet or a shadow but some of them are definitely grey and the edges line up with where it stays white after heating with my receipts you can see that it's white on the inside and grey on the outside and I think the difference is that she is just spraying a whole bunch more if I spray a little bit it goes really grey but if I just keep spraying it goes back to white so here is my new theory well hypothesis on what's going on receipt paper has a special ink on one side that's in two parts kind of like it's frozen in wax the heat makes the wax melt so the parts can come together and make a black molecule it's like how ice cream flavours stay separate when they're frozen but if they melt they can mix and make a new colour with receipts it is a complex process but it's essentially there are three or four things that need to come together to make the black ink plus this new color is kind of fragile it only forms under specific conditions you can see it disappearing when you heat it back up again so I think the products that are working are actually just dissolving up the ink layer and messing up where things are so they can't form the black ink anymore I can check this in a whole bunch of ways with things that are definitely not forming a layer to protect against heat the two sprays that went grey for me have alcohol in them alcohol is really good at dissolving things so let's test alcohol alcohol with water and alcohol with glycerin and water alcohol evaporates really quickly so that's why it's more white when it gets diluted with water and glycerin it stays around for longer so it dissolves more of the ink that's also why you're meant to sanitise surfaces with watered down alcohol not pure stuff there's more time for the alcohol to kill the microbes and this also explains why some receipts were lighter on day two the protectants had more time to mess up the ink we already tested water but here it is again the receipt still works because the ink is too oily to dissolve with just water water and glycerin also doesn't change much because they can't dissolve oily stuff products with a lot of alcohol also make a difference perfume makes it go white dry shampoo makes it grey at the start but eventually it doesn't have a big effect because there's no humectants it evaporates too quickly to mess up too much ink so this is good evidence that alcohol does something but how do we check that it's dissolving? surfactants these are the molecules in soap that dissolve oil off your face they should be able to mess up the receipt as well micellar water has surfactant yep and water with a couple drops of detergent also makes a difference there are also surfactants in moisturisers called emulsifiers they keep the oil and the water together and they are in the cream heat protectants so they should also mess up the receipt sunscreen has alcohol and surfactants so lotion goes white so does a sunscreen spray this explains why some sprays go lighter than a lot of creams but some of them are really dark sprays that have alcohol tend to have a lot of it but some of them don't have any but all creams have emulsifiers and they get rubbed onto the receipt which helps mess it up I also tested an eye makeup remover with volatile silicones and that didn't make too much of a difference probably because it evaporates too quickly to dissolve anything and it's a bit too oily so that's probably what's happening with some of the silicone based products that made the receipt go really dark I also noticed that some of her products that worked really well had HFC which is a propellant that could potentially do something so I also tried compressed air which just has that propellant and not much else no difference the ink being really fragile and easy to disturb is also why sticky tape adhesive keeps it white and if my hypothesis about dissolving ink is correct it also means that we should be able to erase the black with alcohol perfume sunscreen micellar water and moisturiser so this test mostly shows which products are good at dissolving the top layer of receipts and to a lesser extent which receipts were still wet it has nothing to do with which heat protectant works best to find that out you should test on actual hair one brand whose product supposedly failed showed their actual testing and heat protectants could just be conditioning hair so they don't get as damaged with snagging and tools but that is a topic for future Michelle but basically you're looking for products from brands that do proper tests effective ingredients include silicones polymers and hydrolysed proteins and if they contain water make sure you let them dry for a bit before you use hot tools so we did it we explained all the observations pretty well and it only took me about 25 hours not including all the time I spent in the shower thinking about it and now this is going to be a 60-second TikTok video is science fun? I don't know it was really bothering me I couldn't work out what was going on and now I know and am I a better person now? I'm not really sure but I guess I can think about other things in the shower now if you want to know how other hair care products work check out the videos next to me if you want to know more about hair science check out my hair science playlist