Scientist explains: What everyone gets wrong about sulfates in shampoo

Summary

In 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

00:00

🔍 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.

05:02

🔬 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.

10:04

🌦️ 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.

Keywords

💡Sulfates

Sulfates refer to specific surfactants, mainly sodium lauryl sulfate and sodium laureth sulfate, used in shampoos to help clean hair by breaking up oils and dirt. The video challenges the common misconception that sulfates are harsh or damaging, explaining that the cleaning effect of shampoos depends on the overall formulation, not just the presence of sulfates.

💡Surfactants

Surfactants are cleaning agents in shampoos that have a head attracted to water and a tail attracted to oil, allowing them to break down oil and dirt. In the video, the speaker explains how surfactants work at a molecular level and emphasizes that the interaction between surfactants and other ingredients in a shampoo is complex, making it hard to predict how well a shampoo will clean based on surfactant type alone.

💡Hair science

Hair science refers to the study of the structure and behavior of hair, including how it interacts with different products. The video describes how hair science is much more complex than skin science due to the diversity of hair types and the lack of extensive academic research, contributing to confusion around how hair products, such as shampoos, work.

💡Hair diversity

Hair diversity refers to the wide range of hair types, from straight to various degrees of curly or coily hair, which respond differently to products. The video highlights that this diversity makes it difficult to generalize findings from hair experiments, as different hair types may react in unique ways to shampoos, conditioners, and other treatments.

💡Detangling

Detangling involves removing knots or tangles from hair, a process that varies depending on hair type. The video discusses how detangling wet hair is less damaging for curly hair but more damaging for straight hair, due to differences in how water affects the structure and fragility of different hair types.

💡Shampoo formulation

Shampoo formulation refers to the overall combination of ingredients in a shampoo, which determines how it cleans, conditions, or protects hair. The video emphasizes that it's the complete formulation, not just individual ingredients like sulfates, that dictates how a shampoo performs, making it crucial to evaluate the product as a whole.

💡Clarifying shampoo

Clarifying shampoo is a type of shampoo designed to clean hair deeply by removing build-up of oils, dirt, and product residue. In the video, the speaker mentions that clarifying shampoos clean hair more thoroughly regardless of whether they contain sulfates, further demonstrating that product labels and intended function are more useful than focusing solely on sulfates.

💡Supramolecular process

A supramolecular process refers to the way molecules interact without undergoing a chemical reaction, such as how surfactants work together to clean hair. The video explains that shampoos clean hair through multiple supramolecular processes, depending on how the surfactants and other ingredients interact with the oils and dirt on the hair.

💡pH of shampoos

pH refers to the acidity or alkalinity of a shampoo. The video debunks the myth that checking a shampoo's pH is critical for determining its effectiveness, arguing that the complexity of shampoo formulations makes pH a less useful indicator of how well a product will clean or condition hair.

💡Color protection

Color protection refers to the ability of a shampoo or conditioner to preserve hair dye and prevent it from fading. In the video, the speaker notes that some shampoos with sulfates can actually protect color better than sulfate-free options, challenging the common belief that sulfates always strip color from dyed hair.

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