Scientist explains: What everyone gets wrong about sulfates in shampoo
Summary
TLDRIn this video, Michelle from Lab Muffin Beauty Science debunks common myths about sulfates in shampoos. She explains that hair science is complex due to the diversity of hair types and the sparse academic research. Michelle clarifies that the effectiveness of a shampoo isn't solely dependent on the presence of sulfates but on the overall formulation. She emphasizes that the product's intended purpose, such as clarifying or color protection, is more indicative of its performance than whether it's sulfate-free or not.
Takeaways
- 💇♀️ Many people misunderstand sulfate-free and sulfate-containing shampoos; both don't guarantee specific results for hair cleaning or protection.
- 🧪 Hair science is complex, more so than skincare, because hair is incredibly diverse in structure and response to products.
- 🌀 The shape of hair strands (straight, curly, coiled) significantly affects how hair reacts to products and care routines, such as wet versus dry detangling.
- 🌧️ Environmental factors like humidity can affect hair's behavior and product results, making hair studies hard to generalize.
- 👩🔬 Hair science is sparse, with evolving knowledge and inconsistent terminology, even among academic studies.
- 🧴 The overall formulation of hair products (not just individual ingredients like sulfates) determines how well they clean or protect hair.
- 🔍 Predicting how a shampoo will perform based solely on ingredients like sulfates or pH is too simplistic; the entire formula matters.
- 🎨 A study showed that a sulfate-containing shampoo could strip hair dye less than some sulfate-free alternatives, challenging popular myths.
- 🧼 Foam in shampoos and other cleaners doesn't necessarily correlate with better cleaning power; it's often about consumer perception.
- 📊 Reviews from people with similar hair types are valuable when choosing a shampoo, as trying it out on your own hair is the best way to know how it works.
Q & A
What is the main point of confusion regarding sulfates in shampoos according to the speaker?
-The main point of confusion is that people generally misunderstand the role of sulfates in shampoos, with some believing sulfate-free shampoos are less damaging while others think sulfates are necessary for effective cleaning. The speaker argues that both views are oversimplified and not based on the complex chemistry involved.
What does the speaker claim about the state of academic hair science?
-The speaker claims that academic hair science is 'a mess' due to the diversity of hair types, sparse scientific knowledge, and the complexity of hair's interaction with various products and environmental factors.
Why does the speaker say that hair science is more complex than skin science?
-Hair science is more complex than skin science because hair is more diverse, with different shapes and types responding differently to hair care products. Additionally, the way hair interacts with water and other factors introduces more variables that affect how hair products work.
What is the role of surfactants in shampoos, as explained by the speaker?
-Surfactants in shampoos have a dual nature, with a water-loving head and an oil-loving tail, which allows them to help oil and dirt mix with water so they can be rinsed away, resulting in clean hair.
What are the four different ways shampoos clean hair at a microscopic level mentioned in the script?
-The four ways are depicted as microscopic processes where surfactants interact with hair to clean it without undergoing a chemical reaction. These are supramolecular processes involving molecular choreography, and they likely occur simultaneously to varying extents.
Why does the speaker argue that the pH of a shampoo is not a meaningful indicator of its effectiveness?
-The speaker argues that the pH is not a meaningful indicator because the overall formulation of a shampoo, including the interaction of multiple surfactants and other ingredients, is much more complex and influential on cleaning effectiveness than just the pH level.
What is the 'circular reasoning' the speaker refers to in the context of sulfate-free shampoos?
-The 'circular reasoning' refers to the assumption that sulfate-free shampoos are gentle and less stripping because formulators design them to meet consumer expectations based on widespread myths, rather than because sulfates inherently cause more stripping.
Why does the speaker say that foaming is not a reliable indicator of cleaning effectiveness in shampoos?
-Foaming is not a reliable indicator because it depends on how well a product interacts with air and traps air in a thin film, whereas cleaning effectiveness depends on interaction with oil and dirt. These are two different supramolecular processes with no direct correlation.
What does the speaker suggest as a better approach to choosing a shampoo than focusing on whether it contains sulfates or not?
-The speaker suggests looking at the shampoo's intended purpose, such as 'clarifying' or 'color protection,' and reading reviews from people with similar hair types. Trying the shampoo on one's own hair is also recommended to determine its effectiveness.
What is the speaker's background, and why does she feel qualified to discuss hair science?
-The speaker, Michelle, has a PhD in chemistry and is a cosmetic chemist. She usually discusses skincare science but has been paying more attention to hair science, which qualifies her to discuss the complexities of hair care products.
Outlines
🔍 Debunking Hair Myths: Sulfate-Free vs. Sulfate Shampoos
The speaker addresses misconceptions about sulfate-free and sulfate shampoos. While some claim sulfate-free products are gentler and less damaging, others believe sulfates are essential for proper cleaning. Both views are oversimplified, as the chemistry behind hair care is more complex. The speaker, Michelle, a PhD chemist, aims to clear up the confusion by diving into hair science, highlighting the diversity in hair types and how this complexity makes it hard for people to find the right hair products.
🔬 Complexity in Hair Science: Hair is Diverse and Unpredictable
Hair care is far more complicated than skincare due to the variety of hair types—straight, curly, coily, etc.—and how they respond differently to products. The speaker explains that, unlike skin, hair behaves unpredictably depending on factors like shape, length, and moisture. Hair responds differently when wet or dry, and while straight hair is best detangled dry, curly hair is better detangled wet. These differences make understanding hair care difficult, and many scientific questions, like when to detangle wavy hair, remain unanswered.
🌦️ Environmental Impact on Hair Care: Humidity and Variables
The speaker dives into how environmental factors, particularly humidity, affect hair behavior and experiments. Humidity can drastically change how hair responds to products, complicating efforts to study hair. Hair science lacks consistency in terminology and is evolving, making it challenging to generalize findings across different hair types. Even basic concepts like the protein composition of hair are subject to debate, reflecting the complex and sparse nature of hair science research.
🧴 The Importance of Formulation: Shampoo and Conditioner Mechanics
Shampoos and conditioners don’t work based solely on individual ingredients but on their overall formulation. Sulfates, typically sodium lauryl sulfate and sodium laureth sulfate, are surfactants used for cleaning, but their effect depends on the formula and concentration. The speaker explains that the cleaning process in shampoos is a supramolecular one, where surfactants interact with oil and water to remove dirt. The complexity of these interactions makes it difficult to generalize how well a shampoo will clean based on whether it contains sulfates or not.
🔬 Shampoo Science: Complex Interactions at Work
Different surfactants in shampoos behave differently depending on their interactions with dirt, oil, and the hair itself. The concentration of surfactants changes during the washing process, affecting how well the shampoo cleans. The speaker highlights that predicting how a shampoo will work based on its ingredients is nearly impossible because there are too many variables involved, from the shampoo’s texture to how it is applied and even external factors like water.
🧪 Formulation vs. Ingredients: Why Sulfates Don't Define Cleaning Power
The debate over sulfates is oversimplified—whether a shampoo contains sulfates or not doesn’t necessarily predict its cleaning effectiveness. The speaker refers to a study where sulfate-containing shampoos were actually gentler on hair color than sulfate-free alternatives, showing that product design matters more than individual ingredients. Formulators consider consumer expectations when designing shampoos, often aiming for sulfate-free products to be gentler. However, the speaker emphasizes that the formulation, not the presence of sulfates, determines how the shampoo works.
💭 The Role of Psychology in Hair Care: Foam and Cleaning Perception
Humans tend to associate foam with cleaning power, but this is largely psychological. Foam results from surfactants interacting with air, while cleaning comes from their interaction with oil and dirt. Some products, like dishwasher detergents, are formulated to minimize foam because excess foam can cause problems. The speaker concludes that how well a shampoo cleans is not tied to how much it foams or whether it contains sulfates, but rather to the overall product formulation and design.
📊 Conclusion: How to Choose the Right Shampoo
The bottom line is that the presence of sulfates doesn’t determine a shampoo’s effectiveness. Terms like ‘clarifying’ or ‘color protection’ are more useful indicators of how a shampoo will perform. The speaker advises looking at reviews from people with similar hair types to find the best products for individual needs. Hair care is too complex to follow simple rules like sulfate vs. sulfate-free, and consumers should rely on testing products and personal experience.
Mindmap
Keywords
💡Sulfates
💡Surfactants
💡Hair science
💡Hair diversity
💡Detangling
💡Shampoo formulation
💡Clarifying shampoo
💡Supramolecular process
💡pH of shampoos
💡Color protection
Highlights
Common misconceptions about sulfate-free vs. sulfate shampoos debunked.
Hair science is highly diverse, more complex than skincare.
Understanding hair type is key to selecting the right hair care products.
Straight vs. curly hair responds differently to detangling when wet or dry.
Hair products need to be tailored to individual needs and hair types.
Hair's response to products is influenced by factors like shape, moisture, and damage.
Hair science is sparse and there is still much we don’t know.
Hair diversity and external variables like humidity affect hair care outcomes.
Hair science terminology can be inconsistent, leading to confusion.
Shampoo effectiveness depends more on the overall formulation than individual ingredients.
Sulfates and sulfate-free shampoos both have their advantages and disadvantages.
Complex interactions in hair products, such as surfactants, affect how they clean.
Consumer perceptions and product marketing heavily influence shampoo formulations.
Foam doesn’t always correlate with cleaning power in hair care products.
Hair care product recommendations should be based on personal hair type and product testing.
Transcripts
you'll hear lots of people say you have to use sulfate free
shampoo to avoid damaging or stripping your hair
you'll also hear people say you have to use sulfates to get your hair clean
they are both wrong
almost everyone misunderstands this fundamental thing about shampoos and
I think it's why so many people can't find the right products
I'm Michelle of lab muffin beauty science chemistry PhD and cosmetic chemist and person
who usually talks more about skincare science but we are doing hair today
I've been paying more attention to hair science on the internet lately and there are
so many completely wrong explanations and strong opinions and just people yelling at each other
but because I love pain apparently I am going to talk about it
I'm starting with sulfate versus sulfate-free shampoos
I've talked about it a bit before but I'm going into more depth because I think if
we really dig into the chemistry of it a lot of things about hair start making more sense
but before we talk about sulfates we have to talk about the state of hair science
not just internet hair science but actual academic hair science
it is a mess
there are three big reasons I think there's so much confusion
reason one hair is really diverse so much more than skin
different hair just does not respond to hair care products the same way
skin care seems complex but when you break it down it's actually pretty straightforward
maybe also it seems that way to me because I've been talking about it for so long
with skin type there's oily and dry and in between
then you have concerns like fine lines pigmentation acne
it does take a while to understand your skin and find the right products for it
I have to plug my ebook because I keep forgetting to do that
it walks you through that process
but when it comes down to it ingredients tend to work pretty similarly for everyone
if you have a hundred people use glycerin on their skin you might have 60 people's
skin get more hydrated and improve 20 people's skin stays around the same
and the final 20 might get worse for some reason like the glycerin helped
some other ingredients penetrate and the skin got irritated or they have an allergy
there is still complexity but you wouldn't have like half the people's skin dry out more
but that's kind of how it is with hair
even just with the shape of the strands you have straight curly a million different levels
and types of curly kinky tight coils the coils might be rounder or flatter or a mix
and shape makes a massive difference to how hair responds to different products
variation in geometric shape is just not something we have to think about much with skin
take wet versus dry detangling for example
the way water interacts with hair is weird
I'm not going to go into too much detail
here because that's a whole topic for like five videos but in short
it weakens the bonds gluing the inside of the hair
together which is why hair gets stretchy when it's wet
but it adds stickiness to the outside of the hair so hairs stick together
more easily and you need to use more force to get the comb through
water also raises the cuticle scales
these are the roof tile looking cells on
the surface and that means they can bash against each other more and chip
so all of this means it's less damaging to to detangle hair when it's dry
but that's just for straight hair it is the opposite for curly hair
all of these effects still happen but changing just the shape of the hair strand
that is enough to change the physics of how the hair interacts with a comb
the cuticle scales still stand up more the curly hair is still
weaker on the inside and sticky on the outside the hair is still more fragile
but there are two big differences
first off the hairs stick to each other less because there is less
alignment or tessellation between curly hair strands compared to straight hair
it's like how when you cook spaghetti they stick together much more than with spiral pasta
on top of that the weakening of the bonds inside the hair actually makes the curls loosen in shape
a looser curl means that geometrically there's
less chance of tangling and causing damage and breakage
so the change in the physics of how that curl interacts with the comb
that can offset the damage from manipulating wet fragile hair and overall you get less breakage
there's a few studies showing this
but where is the line
is it better to detangle say wavy hair when it's wet or dry
what if you use a brush versus a comb or a different type of brush
what if you detangle it from the bottom up or just straight from the top
what happens if you partly dry the hair
those answers just
don't seem to exist
and we are just talking about water and hair shape
we're not even talking about other ingredients
how often you wash your hair
how much damage you have
the type of damage you have
if you bleach or straighten your hair
or how long your hair is or how oily it is
there are a lot of variables
and this kind of overlaps with reason two hair science is just really sparse
we just do not know that much about hair
I used to assume that hair was really straightforward
I mean hair is dead skin is alive
if you're doing tests on hair strands it should be really easy
you just buy a bunch of hair
that is so much easier than finding volunteers
but because of all this diversity with hair every experiment you do - you just
can't necessarily generalize this to other types of hair
on top of that there are tons of other variables that make a huge
difference to hair like what humidity the experiment started and ended up with
when I go places with high humidity it gets a little extra body okay
that alone can massively change the results and we all live in places with different humidities
and the humidity changes throughout the day it changes in different rooms
so it isn't like if every study did experiments at 20% humidity that would solve the problem
hair scientists don't even know the structure of hair in that much detail
the understanding is still evolving relatively quickly
and there just isn't that much consistency with terminology even in the peer-reviewed literature
so for example around the late 90s some hair scientists just decided half the
protein in hair wouldn't be called keratin anymore and they have good reasons for that
but not everyone got the memo or maybe some hair scientists just didn't agree
so you'll still read things like "hair is 80% keratin by mass" even in this paper from 2017
and this isn't a huge deal here because it is pretty clear they're using that old definition
but if a paper says "we concluded that this
ingredient works on keratin and hair" do they mean keratin or do they mean
keratin
[muffled screaming]
Reason 3 hair products aren't just about individual ingredients
the two main hair products shampoo and conditioner
the way they work isn't about the individual ingredients the
overall formulation is really important
and yeah we say that a lot about skincare but it is even more the case with hair care
and this is central to this debate about sulfates and shampoos
sulfates usually refers to sodium lauryl sulfate and sodium laureth sulfate
these are two of the cleaning ingredients or surfactants that
you find in things like shampoos and cleansers
surfactants are special because they have a head that likes water and a tail that likes oil
as you hopefully know from
Life
oil and water don't usually mix
so surfactacts can help oil break up and mingle
with water so you can rinse it away and end up with clean hair or skin
the tails are pretty similar in surfactants so most of the time we're talking about the heads
sulfates have sulfate head groups
chemists are not imaginative when it comes to naming
and yes if we compare sulfates on their own with other surfactants on their own
they have good cleaning ability but because it's hair science there is more complexity
these four diagrams show four different ways that shampoos clean at a microscopic level
each of these diagrams is read from left to right
the pink tadpoles are the surfactants and you can
see that the surfactants are coordinating to clean the hair
this is called a supramolecular process where the
molecules are interacting without going through a chemical reaction
it's a bit like molecular choreography
now this isn't like four separate processes
all four of these are probably happening on your hair at the same time to different extents
there are probably still more mechanisms still to be discovered
how much of these depends on the formula of the shampoo because the pink tadpole surfactants
won't all be the same they'll have different tendencies to interact in different ways
but it also depends on what sorts of stuff or soils you're cleaning off
because they are also part of this choreography
so for example if you have bigger blobs of oil on your hair then this one is probably happening more
because some of that oil breaks off multiple times instead of all of it coming off at once like here
but if you have big particles that don't break up easily then it might all just be figure 4
this one happens more at high surfactant concentrations and that is another variable
and that's not just about the concentration of the surfactants in the formula
at the start of the shampooing process you've just put the shampoo on your hair
it's at maximum concentration but if you add more water or you start rinsing then
the concentration will decrease and you might have less of this happening
and this is already getting pretty complicated but it's still a massive
oversimplification because hair science will not give us a break
if you look at the ingredients of almost any shampoo it'll have three or more difference
surfactants that means that these pink tadpoles in the diagram aren't all the same
if you change the ratio of the ingredients or swap
one of these out with something else then the shampoo might work quite differently
plus there's a bunch of other ingredients that aren't shown here like polymers and
oils and those will also interact with the surfactants and affect how it cleans
and on top of that things like the texture of the shampoo the opening of the bottle that's
going to change how much you dispense and how the shampoo spreads on hair
so in case you didn't notice it is really complex
and what that means is trying to predict what happens just by looking at whether
some of these pink tadpoles are sulfates or not - that is just not going to tell you much
it just isn't as simple as "it has sulfates
it'll clean better" or "it'll strip or degrease your hair"
if it was it would be so much easier for everyone to just find the right shampoo
same with the pH of shampoos I see lots of people saying you have to check the
pH and make sure it's acidic and again that is just not a
very meaningful piece of information when the whole thing is so complex
it's a bit like trying to predict how a food tastes from how yellow it is
and even if you knew the full formula of a shampoo every single ingredient what
concentration they're in where they got the ingredients it would still be pretty
much impossible to predict how it's going to interact with itself let alone with
different types of soils on your hair at different stages of the shampooing process
it takes a ridiculous amount of computational power to model
a much simpler sort of system with way less moving parts than a shampoo
this is why cosmetic formulators spend so much time just during trial and error making formulas
and trying them out changing little things about a formula can make a huge difference
here's one example
Good Housekeeping did this test with 10 shampoo
and conditioner pairings that were meant to protect colour
some of these had sulfates and some didn't
there were salon and drugstore brands
the set that stripped hair dye the least had sulfates
it's this tresemme set
they also have this article where hair scientists talk about how complex it is to formulate a
shampoo but even with their own results as proof and two scientists with PhDs explaining
to them that it's not about sulfates versus no sulfates their article on color stripping
and shampoos still has this BS about sulfates "sudding" the hair and causing pigment loss
these myths run deep
but I think a lot of us have had the experience where we try a sulfate free
shampoo and it does feel like it's gentle or it doesn't clean enough
the way you frame it probably depends on whether or not your hair likes that
and the reason for this I think is a sort of circular
reasoning that happens quite a bit with products
formulators know that people looking for sulfate free probably want something that
cleans less they know there's all these widespread myths about sulfates being
harsh they've been going around since the 90s like in this email forward
"SLS is used to scrub garage floors and it is very strong"
even if the formulator didn't know about all this because I don't know
if they've been hiding in a hole it's probably on the product brief
that's the description of the product that the formulator works off it's
usually written by marketing people based on consumer research it'll have
the marketing claims that they plan to put on the products so chances
are the brief says "sulfate free" as well as "gentle" and "not stripping"
so there's a good chance that if you grab a random shampoo with sulfates
and a random shampoo without sulfates the one with sulfates will clean better
it's not because just adding sulfates automatically makes a shampoo strip more
we saw that it can be formulated to strip colour the least
it's just because of intentional product design
the formulator formulated with sulfates and to make it clean more
they might have also changed some of the other
ingredients to make it feel like your hair is cleaner
but brands don't all have the same idea of what counts as gentle and some brands
choose not to follow this consumer trend so there's going to be lots of exceptions
it's like how if you grab a shampoo in a black and green bottle there's a pretty
good chance it'll smell minty because product designers have decided that is what men like
this is exactly the same situation with foam and cleansers
how well a product foams doesn't tell you about how well it cleans
what's happening on a molecular level is different
how well something first depends on how well it
interacts with air how well it traps air in a thin film
cleaning is about how well it interacts with oil and dirt
both cleaning and foam rely on surfactants but apart from that there's no real correlation
between which surfactants foam best and which ones clean best
and there's so much that depends on the overall formula there are lots of
other ingredients that help to create a nice foam
again both are complicated supramolecular processes there are so many moving parts
but if something doesn't foam when we use it we tend to feel like it's
not cleaning properly it's a purely psychological thing and I personally
still have this gut feeling even though I know all of this chemistry behind it
humans did not evolve to be perfectly rational in our feelings
so formulators make sure that shampoos and other
cleaning products usually foam really nicely for us
but if we don't see it then it doesn't have to foam to convince us
one example is detergents for dishwashers they're actually kind of formulated the opposite way
they have to clean really well with as little foam as possible because foam causes pressure
and if that builds up then it can make the dishwasher leak and flood our kitchen
sploosh
sploosh
bottom line sulfate free sulfate containing doesn't really mean much
how well a shampoo cleans is way too complicated to predict that easily
it's much more useful to actually look at what the shampoo is trying to tell you
if it says clarifying then it's a shampoo designed
to clean your hair better doesn't matter if it has sulfates or not
if it says colour protection it can have sulfates
and still strip dye less than a sulfate-free shampoo
if you stick to these rules about sulfate versus sulfate free then
you would have missed out on the least colour stripping shampoo
it's also really useful to look at reviews
from people with similar hair to you and try it out on your hair
let me know what you thought of this deep dive into hair science what I should talk about next
if you enjoyed this video I would really appreciate it if you gave it a thumbs up
and subscribe more nerdy hair science videos are popping up around me now
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