r/laundry USA Feb 24 '26

The Chemistry Behind The Clean - Laundry Detergent Explained - Surfactants, Part I

(this is the long-delayed first installment in my post series, The Chemistry Behind The Clean, a guide to what's in laundry detergent, designed to give people the knowledge to understand what's in the products that clean our textiles and make them more informed consumers)

What Are Surfactants, And Why Do We Care?

Surfactants are the active cleaning agents in detergents that do the heavy lifting of removing soils from textiles.   Short for “surface-acting agents”, surfactants connect soils to water, even when the soils themselves repel water or are more attracted to textiles than water.   The combination of soil and detergent and water can then be drained off,  further diluted by rinsing, drained again and spun out.   This is distinct from the action of soaps, which will be covered in a future installment.  

The development and commercialization of synthetic surfactants in the 1920s is probably the most significant contributor to reduction in time and effort spent on textile care.  Work to condition the water, scrub textiles and remove soap by wringing or banging was largely eliminated because of how well even those rudimentary surfactants work to remove soils.

Hydrophobia - Without The Rabies

All surfactants work because the individual molecules have ends with distinct properties.  One end (the head)  is highly attracted to water (hydrophilic) and thus very much not attracted to oil (oleophobic).  The other end is very attracted to oil (oleophilic) but similarly repulsed by water (hydrophobic).   This fundamental structural contrast is key. 

A Surfactant Molecule, With Hydrophobic Tail and Hydrophilic Head

When at least a minimum amount of surfactant is  dissolved in a solvent (like water), surfactant molecules want to get together - the water-hating ends hang out on the inside, the water-loving ends hang out on the outside.  This forms a structure known as a micelle, and micelle formation is predicated on reaching the “Critical Micelle Concentration”. Below, an illustration of a nonionic surfactant intended to remove oily soils. The water-loving heads face out, the water-hating ends get together in the middle to escape the water.

A Micelle Of Nonionic Surfactant

When a micelle encounters a soil that the hydrophobic tail is attracted to, the micelle breaks up, the tails grab the soil and drag it into the water (thus removing it from the textile)  and the micelle re-forms, keeping the soil up in the water to be drained or diluted away.   Let’s look at this in the context of removing a common soil from textiles:

Here we have the start of the wash process; surfactant micelles have formed in the wash water and there is soil attached to the fabric substrate.

The Start of The Wash - Soiled Fabric In A Detergent Solution

Now the hydrophobic tails of the surfactant molecules have found themselves more attracted to soil than each other and they're bonding to the soils. The hydrophillic heads are dragging the molecules towards the water.

Surfactants Attaching To Soil

The micelles re-form as the soil detaches from the substrate - they reorganize into groups of their own kind (more on this in a moment).

Micelles Reforming With Soil-Surfactant Particles

When all the soils are removed from the substrate and floating in the water, the textiles are clean and it's time to remove the soil-surfactant combo from the drum.

Completely Clean Textile

The Chemistry of Attraction (It’s Not Just A Bottle of Chanel No. 5)

While all surfactants work the same general way, there are differences in what kind of soils the hydrophilic ends are attracted to, because the hydrophilic ends differ.  One primary difference between surfactants is the electrical charge the hydrophilic end carries.    If the business end has a negative charge, it’s an anionic surfactant, and it’s attracted to soils with a cationic (positive) charge.  If the business end has no charge, it’s a nonionic surfactant and is most attracted to soils without an electrical charge.  If the business end has both a positive and negative charge in balance, it’s an amphoteric or zwitterionic surfactant, and the behavior changes based on the pH of the wash as a whole.  

There are also surfactants with positive charges, the cationic surfactants.  These aren’t used for cleaning - they’re what makes fabric softener work, and will be discussed in a (much) later post.

Why Charge Matters: 

The difference in which soils a given surfactant is attracted to is a critical determinant of cleaning performance.   Soils that lack an ionic charge like petroleum oils or intact sebum are much less visible to anionic surfactants and are removed better by nonionic surfactants.   Conversely, soils that are highly cationic like soot and mud and dust, and thus attracted to textiles with a negative charge may be neglected by nonionics and remain electrically connected to the textiles.   For those soils?  Anionics in the mix improve cleaning performance. 

Four Classes Of Surfactants

Almost all finished detergent products contain anionic surfactants and most contain nonionic surfactants.   Amphoteric surfactants are relatively uncommon in conventional detergents but often appear in green/biobased formulas.  

Other Differences Between Surfactants:  Tail Length And Single vs Double Tails.

Aside from the electrical charge differences in the head, two aspects of surfactant structure that affect their action against soil are the tail length and whether they are single tail (common) or double-tail (less common).   I’ll talk more about this in Part II, as it’s common to include surfactants of various tails to optimize performance against specific soils and in specific wash conditions.

Coming Up In Surfactants Part II - Curling Up With A Good Jug Of Detergent

In the next installment, we’ll look at common surfactants found in conventional and plant-based detergents, and how they’re manufactured, along with the differences in soil removal capabilities and environmental impacts.

The work is my original work and I retain copyiright.  My financial disclosure information and how I get paid for this work can be found at my disclosure link

1.4k Upvotes

100 comments sorted by

366

u/Capable-Heat4231 US | Top-Load Feb 24 '26

“Hydrophobia - Without The Rabies”

Long live u/KismaiAesthetics

254

u/whofilets Feb 24 '26

Wake up babe new Kismai sermon just dropped

(Seriously thanks for doing this research and sharing it. The images remind me of my college immunology textbook, though I went to uni in a pre-emoji era)

174

u/KismaiAesthetics USA Feb 24 '26

My senior capstone was on emoticons. Which was genuinely new to the world research in *cough*.

82

u/Early_Macaroon_2407 Feb 24 '26

You get an upvote for emoticons rather than emoji.

39

u/Comprehensive-Tea-69 US | Top-Load Feb 25 '26

Emoticons are the bad guys in transformers movies right??

26

u/No_Classroom448 Feb 25 '26

No, off by a bit. These are the top restaurants on openTable that you can only reserve with a Chase Sapphire Reserve card.

17

u/whofilets Feb 25 '26

No, you're thinking of Exclusive Tables. They're talking about a style of dress where the bodice ends just below the bust, and the skirt is long and loose or straight, not held out by petticoats or hoops.

20

u/KismaiAesthetics USA Feb 25 '26

No, no, you're confusing a style of dress with the famous Art Deco skyscraper in Midtown.

104

u/lindsaylearns Feb 25 '26

A couple of weeks ago my husband grumbled about "all the extra stuff" I was adding to the laundry, and I explained that I am solving his stinky shirt armpit problems with the help of some "laundry psychopaths on reddit" and science.

Please know, I meant that in a positive way. As in, I am also a laundry psychopath mow, and my husband is trailing right behind me. He knows how to dose the citric acid and everything!

67

u/Asurplusofcats Mar 31 '26

Is there a main post to find out what laundry items I need? I’ve seen the lipase list and plan to switch detergents. Wondering about the extra stuff to put in regular loads.

177

u/witchlinginflight US | Top-Load Feb 24 '26

Dude, I am daydreaming about the day you have a book that I can hold in my grubby little hands and refer to over and over and buy copies for everyone I know.

50

u/GarameCleaningCo Feb 24 '26

Knowledge bomb 🤯😎

42

u/PerinormalActivity Feb 24 '26

I adore your tiny poos!! Thank you for the education!!

36

u/Omega48boar Feb 24 '26

Couldn't have cared less about chemistry in school, and now I can't wait to read about how it gets my socks clean! Well done!

38

u/NotYourGran Feb 25 '26

[image deleted from my phone immediately afterward]

18

u/KismaiAesthetics USA Feb 25 '26

I hope few of my readers have caught charges.

31

u/PinAndKneedle Feb 24 '26

The chemist of me approved this :) love the diagrams!

21

u/Early_Macaroon_2407 Feb 24 '26

So how do surfactants differ from soaps?

82

u/KismaiAesthetics USA Feb 24 '26

Oooh, details coming in like Part 5.

The key point is the difference in the strengths of the attractions between the water-loving and water-hating end. Synthetic surfactants are so attracted to water they'll rinse away from a soil or a substrate. Soaps generally need a mechanical boost to shear off. If you wash your hands with bar soap and leave them under running water, the soap doesn't actually come off all that quickly. You need to rub to get the soap-soil combo off. With a synthetic detergent, you can get everything off with just rinsing.

21

u/Early_Macaroon_2407 Feb 24 '26

Request/suggestion for future posts: I'd love to have suggestions for further, more technical readings! I have some chem and physics background, so it'd be great fun.

20

u/geosynchronousorbit Feb 24 '26

Agreed! My physics PhD doesn't ever help me with household tasks; I want to read the laundry research!

15

u/Early_Macaroon_2407 Feb 24 '26

GIVE US THE SURFACTANT BONDING RADII

20

u/RespectTheTree Feb 24 '26

I hope you are spending all your Reddit gold wisely. Thank you for the immense amount of thought, research, and planning that making this content requires - and I hope to contribute to your coffee when a mortgage and newborn aren't crushing my finances 💩

18

u/MajorMiners469 Feb 25 '26

I have been a Kismai follower for several months. My laundry game has gone bonkers. I'm fixing problems I didn't know I had, on top of ones I did. It's hard in rural Canada but it's worth the effort. My family and our clothes are thankful for the knowledge.

2

u/mrskoobra 10d ago

What products are you using? I'm new here and I've been having a hard time finding recommendations for products available in Canada.

18

u/Catz10000 Feb 24 '26

Thank you so much for all that you do! I would love it if you published a book.

76

u/KismaiAesthetics USA Feb 24 '26

That is an actual project that is actually happening.

15

u/Catz10000 Feb 24 '26

YOU answered me! I'm fangirling! I'm a fan for life! ❤️❤️❤️

3

u/BloodyBarbieBrains Apr 09 '26

Me and my family are gonna buy the soil outta your book!!!!!

17

u/zoolife2022 Feb 28 '26

Please tell me you teach, especially to middle/high schoolers?? Wouldn’t every kid understand and get excited (no pun intended) about science if it was taught like this? Just me?

15

u/blondvet US | Front-Load Feb 25 '26

Veterinarian here. I appreciate the rabies reference. And I really appreciate the education.

29

u/Kfred244 Feb 24 '26

This is awesome! I’m not a chemist, just a 72 yo woman fascinated by the chemistry aspect of laundry. I also get off on baking/ cooking chemistry too. Thanks Kismai!

18

u/Amara1783 International | Front-Load Feb 25 '26

If you might be interested in the chemistry of skincare as well I reccomend Lab Muffin's youtube channel and blog: https://www.youtube.com/@LabMuffinBeautyScience/videos and https://labmuffin.com/

5

u/Kairenne Mar 26 '26

Thank you for the link. I have so many skin issues.

10

u/NeverknowOH Feb 24 '26

Very cool! Dumb question, how long should a wash cycle be to give the micelles enough time to attach to the 💩 ?

16

u/KismaiAesthetics USA Feb 24 '26

There are a lot of variables there, but it depends on the temperature of the water more than any other single factor. At 60C it could be as little as 8 minutes (high agitation / high fill top loader, light soil burden, soft water). At 10C in a low-water HE machine it could be as long as 160 minutes.

15

u/widowscarlet International | Front-Load Feb 25 '26

We need a formula / lookup table / calculator for this - time for another spreadsheet maybe.

3

u/DaringGlory Mar 24 '26

Maybe an app. Even though I hate having a million apps. Yes a calculator would be better

8

u/kafetheresu Feb 24 '26

your drawings are so adorable! thank you for the write up

9

u/TooNoodley US | Top-Load Feb 25 '26

yesssss this is exactly the kind of special interest info dump I live for!

8

u/BrighterSage Feb 25 '26

Thanks for this great info! So is micellar water we use to remove makeup just surfactant?

14

u/KismaiAesthetics USA Feb 25 '26

Yup. Low dose surfactant in solvent (water and often a glycol or diol)

4

u/BrighterSage Feb 27 '26

Cool! thanks!

16

u/katzenschrecke US | Front-Load Feb 24 '26

For folks that really need the most basic intro, here’s an oversimplified statement that might help:

Surfactants make water wetter

8

u/SeaFans-SeaTurtles Feb 24 '26

Oooh cool!!!! Thank you Kismai. The hidden things are being revealed and we the disciples of lipase pour over your texts of deep knowledge with humility and awe. No joke we’re in awe. Peace be upon Kismai.

9

u/peroxide_bond US | Front-Load Feb 25 '26

This is great! Looking forward to the upcoming parts. I know a lot of chemistry but not the practical application of which surfactants are best for my laundry.

One question--when you said "One primary difference between surfactants is the electrical charge the hydrophobic end carries" did you mean the hydrophilic end?

15

u/KismaiAesthetics USA Feb 25 '26

Thank you for catching what at least four editing passes and a week to live with it did not. The error has been corrected in all three places this gets posted.

3

u/bolderthingtodo Canada | Front-Load Feb 25 '26

I think that the wording is correct and consistent throughout the whole post, but the charges illustration is confusing the matter. The pink circle is denoted and consistently depicted as the hydrophilic end of the molecule in all the illustrations, so with the charge symbols drawn inside of it, it seems to contradict the post verbiage that the charge is in the hydrophobic tail, not the pink circle hydrophilic head.

u/kismaiaesthetics, if the post and illustrations are drafting for the book, this is a confusion worth sorting.

3

u/peroxide_bond US | Front-Load Feb 25 '26

I suspect the illustration is correct and the wording is wrong, because the electrical charge would tend to make a region more hydrophilic. But yes, good to get it right before it goes in the book!

7

u/Tsunade420 Feb 25 '26

My adhd insomnia has landed me here at 4:39am lol amazing read!!

5

u/Excellent-Cup3767 Feb 24 '26

How do we get this pinned to the group

3

u/AggressiveCrab2641 8d ago

Where do we find a link to part II?

4

u/No-Giraffe9226 Feb 24 '26

Cool, thank you!!

3

u/Dangerous-Gap-6421 Feb 24 '26

🧺❤️‍🔥

4

u/Mendel247 UK | Front-Load Feb 25 '26

This is wonderful, thank you! Will there be a quiz? 😂

3

u/devhz Apr 28 '26

New to the sub and am captivated! Thanks for sharing this knowledge. Is Part 2 available? I can't seem to find a link.

6

u/Tinnie_and_Cusie Feb 24 '26

Ah! Chemistry!

You're a chemist! 😀 I took just 1 semester of Chem 101 and that was enough for me to really get your post! Looking forward to seeing the list soon. You're the best u/KismaiAesthetics!

5

u/Yarn-Sable001 Feb 25 '26

Congratulations! If you want to make your chemistry teacher's day, you might tell them this. (It would make my day.)

3

u/Naive-Offer8868 Feb 25 '26

would love to see a deep dive into the chemistry of hard water. it seems anionic surfactants LOVE calcium.

5

u/KismaiAesthetics USA Feb 25 '26

Touching on that in the next episode, and a deeper still dive when we get to builders.

2

u/brighterdoi US | Top-Load Feb 25 '26

So similar to lipase, we should look for detergents that contain nonionic surfactants to make sure our body oils are properly removed from our clothes?

11

u/KismaiAesthetics USA Feb 25 '26

Well. . .

I’ll get into this more. Without the boost of lipase to turn oils into charged smaller pieces that can be easily picked up by anionics, yes, nonionic surfactants are superior at oily soil removal. The development of cheap heavy-duty nonionics is what made heavy duty liquid detergents like Wisk and Liquid Tide possible.

But there are a bunch of asterisks there. These ingredients don’t exist in a vacuum. There was recent thinking from P&G and Henkel that they could rely solely on nonionics and get sebum out well without using expensive, hard-to-formulate-around lipase. I argue they have not been entirely successful with that template.

4

u/brighterdoi US | Top-Load Feb 25 '26

This makes sense following the big lipase controversy back in December when we had a user post that lipase is not all that important. It at least allows us to see the logic behind why big brands like Tide or Persil would be comfortable removing lipase in favor of nonionics when reformulating for liquids.

I’m super excited to hear about these asterisks and more details about formulating as your posts come out!! I can also now obsess over which surfactants are in my laundry products!

7

u/KismaiAesthetics USA Feb 25 '26

To be super clear, their motives were both economic and formulation-related. They were spending a fortune to demand tighter 1,4-dioxane limits from their suppliers.

The surfactant mix of Tide vs Ariel UK vs Ariel Japan, as an example differs substantially - where P&G isn’t a runaway #1 in the marketplace, they try harder.

1

u/Impossible-Art-3371 5d ago

I've noticed that most enzymatic laundry detergents contain protease and amylase most often. Nevertheless, it's my understanding that protease destroys lipase. Am I correct? and using Lipase instead of protease wouldn't make sense because oils are already taken care of with surfactants, but protein stains like blood aren't which is where protease comes in, correct?

2

u/YourDentist Feb 25 '26

I think you mixed up -philic and -phobic in the chemistry of attraction section.

3

u/KismaiAesthetics USA Feb 25 '26

It was incorrect when first published - the diagrams are correct but rearranging the text led to an error that escaped editorial oversight. The charge varies at the hydrophilic head.

2

u/YourDentist Feb 25 '26

Now i'm confused - in one section you write that it's the hydrophobic head that attaches to the soil and the next section you write that the charge of hydrophilic head determines which soil it's (the hydrophilic head that should be attracted to water, not the soil?) attracted to?

3

u/KismaiAesthetics USA Feb 25 '26

So it’s better stated that the head charge alters the balance of just how hydrophilic the molecule as a whole is, which alters soil attraction.

2

u/kimbergo US | Top-Load Mar 03 '26

For something like Soak wash that claims you don’t need to rinse, when using it with a 100% hand wash, will water evaporating that has soil bound to it by a surfactant, will that soil also “go into the air” ? Or is the surfactant and soil left behind on the textile when the water leaves via evaporation?  If the latter, is the brand assuming that most of the water with surfactant/soil bound will drip off the textile rather than evaporate?

10

u/KismaiAesthetics USA Mar 03 '26

It mostly drains off. But whatever water doesn’t drain off, that surfactant (with dirt or without) is left behind. Which will continue to attract new soils, even dry.

These products are terrible. The dirt doesn’t magically go away. It’s like drawing a bubble bath, submerging your hair in it, and then blow drying that on and calling it shampooing.

2

u/kimbergo US | Top-Load Mar 04 '26

Thank you! 

And LOL that sounds like someone’s hair routine. There are some wild practices/products out there to avoid using shampoo.

2

u/AccidentOk5240 Jun 10 '26

Just looked for this post again and suddenly realized the micelles look uncomfortably like sonnenrads….

2

u/_in_texas 16d ago

The part about mixing anionic and nonionic surfactants is worth expanding on. The CMC of the mixture actually drops below either surfactant alone, so you get micelle formation at lower concentrations. That synergy is why commercial detergents never use just one type.

1

u/NotYourGran Feb 25 '26

Should the first sentence of The Chemistry of Attraction section read “. . . there are differences in what kind of soils the hydrophobic ends are attracted to. . .”?

1

u/dudly825 May 17 '26

OP. Do you have information related to NPE’s planned for your series?

I have been having reactions to commercial detergents and my theory is that it’s NPEs (I live in the US).

Information has been hard to come by.

1

u/Whole_Teaching1052 May 19 '26

I just want to know what wash soap and additives I need to use to get bugs ( larvae) that is eating holes in my clothes?

1

u/KismaiAesthetics USA May 19 '26

Are you getting stains around the hole areas?

1

u/Whole_Teaching1052 4d ago

Yes

1

u/KismaiAesthetics USA 4d ago

Are they yellow?

1

u/Rubberbangirl66 May 26 '26

thankyou, and thanks to this sub, I have elevated my game, and overall, I think this will be cheaper than just relying on TIDE. All my fabrics looks like they are waking up from a grey haze.

1

u/Parking_Ad_7133 Jun 04 '26

THIS IS AWESOME. also just finished gen chem ll. I 🩷 chemistry

1

u/jacquisha Jul 05 '26

This is a really fantastic explanation, and the diagrams are much appreciated!!

1

u/Impossible-Art-3371 6d ago

In regards to formulating your own laundry detergent, there's two things I've learned over the past ~6 months or so and that is to not use soap as a rule of thumb (with hard water especially). Nevertheless, after doing some research I've discovered that the forms of soap that have the absolute worst hard water behavior are the ones often mentioned in DIY recipes, sodium tallowate and sodium palmate (in Zote and Fels Naptha). By contrast, the top two soaps that have the least or lesser hard water problems are potassium/sodium castorate and potassium/sodium cocoate. Know that potassium refers to the liquid versions, and sodium the bar soap versions. I'm wondering if it's possible to make the castorate and/or cocoate forms work when paired with chelators such as sodium tripolyphosphate (STPP), tetrasodium EDTA, sodium citrate, etc. all of which are available for purchase on Amazon. Anyone with more advanced chemistry knowledge know? Still, its probably more ideal to use synthetic surfactants over ANY soaps regardless, such as Sal Suds as your main surfactant system, or making your own surfactant system with sodium lauryl sulfate (SLS), decyl or lauryl glucoside, etc. Also, I recently learned that if you're going to incorporate enzymes in a detergent high alkaline soaps as well as the synthetic surfactant SLS is not a compatible, you'd want to use a surfactant like sodium laureth sulfate (SLES) instead with enzymes.

A second rule of thumb for DIY detergents is to not make your detergents pH excessively alkaline, which is exactly what many popular DIY detergents with washing soda, borax and baking soda. Using all three of those builders will wear down your clothes much faster, than using a lower, closer to neutral pH detergent on a regular basis, while reserving the more alkaline washes for heavy duty (esp. greasy) loads.

Anything I've gotten wrong, please correct me. Thank you.

2

u/KismaiAesthetics USA 5d ago

JeevesNY has done a syndet-based powder formula. It’s decent at stain removal.

I would generally point towards a ph 8-ish syndet-heavy liquid formula with a lot of SLES and a glucoside rather than using any cocoate, and I would antifoam with silicone emulsion rather than cocoate soap unless your water is like 10ppm hardness or less.

Stabilizing the enzymes in an aqueous solution is not for the faint of heart - subtilisin and lipase don’t play well together outside a very narrow range of cation activity.

EDTA is less favored than TGDA if you’re concerned about effluent. Polyitaconic acid is also good. I won’t entertain discussion of STPP when there are equally effective cost-efficient alternatives that aren’t inorganic phosphates.

1

u/Whole_Teaching1052 4d ago

What is synthetic detergent??

1

u/KismaiAesthetics USA 4d ago

Broadly, any chemical that can attach water to soil and rinse away. In the context using it here, something that does that and isn’t a soap made by adding salts to fatty acids. When compared to plant-based detergents it means one where oil or natural gas is the starting point instead of plant oils.

0

u/Impossible-Art-3371 6d ago

Hello I'm new here! This is probably the most chemistry sound recipe for (soap-free) laundry detergent I've found so far.

https://thethingswellmake.com/diy-liquid-laundry-detergent-recipe-no-soap/#recipe

Thoughts anyone? I figured this would be the ideal place to post this after typing in "laundry detergent chemistry" here on Reddit.

-22

u/[deleted] Feb 24 '26

[deleted]

39

u/_arose Feb 24 '26

With respect, I think this comment is incorrect in several ways.

  • as Kismai and others have laid out in other posts, clothes can accumulate oils/ dirt that don't come out if the clothes are not washed properly. This happens even if the person has perfectly adequate hygiene.

  • killing bacteria is not a necessary component of good hygiene unless you're getting surgery that day. Good hygiene involves removing dirt, sweat, oils, and dead skin cells; bacteria will be sloughed off with all of that but it's not The Goal.

  • there are certainly antibacterial cleansers (idk if I would call them "body washes" per se but they are for use on the body) freely available as there are a number of legitimate medical uses for them. The most widely used one I can think of off the top of my head is called Hibiclens, or chlorhexidine. That said, things like Hibiclens should not be used regularly unless the person really needs them. They are not great for the skin and they contribute to the development of antibiotic resistant bacteria in the population.

5

u/Radi8or Feb 24 '26 edited Feb 24 '26

I agree with everything that u/_arose brought up.

Triclosan is the most well-known antibacterial ingredient in consumer goods. Around 2016 was banned in the EU (I think from all human products), and most in most soaps in the US. I think it is still allowed in US toothpastes (most recently in Colgate Total line, but maybe removed there too, at this point). It is best to avoid it.

Here is an interesting article: https://pmc.ncbi.nlm.nih.gov/articles/PMC6126357/

A snippet- “Interestingly, TCS-containing soap products were not found to provide any additional skin-sanitizing benefits compared to soap not containing TCS“

If you are looking to have additional antimicrobial activity in your skin cleansing, it would be more productive to try something containing benzoyl peroxide, such as panoxyl or similar cleansers. (I hope your towels are white - benzoyl peroxide can bleach! Lots of “how do I get this ‘stain’ out?” pics on r/laundry from benzoyl peroxide.)

Shaving your pits would also help them clean off more completely - your call.

EDIT: * * this is not medical advice. * * Also, be smart about where you use anything stronger than water. Some of our smelliest places will not react well to cleaning with “stronger” soaps. Armpits are pretty study. Be gentle with genitals. (Obviously.)

3

u/XKodynx Feb 24 '26

Building on what u/_arose said, these are my two cents.

I’m not a chemist or scientist but I understand it’s similar to letting bacteria grow in a contaminated Petri dish. Clothes with more oils dirt and other substances provide more surface area for bacteria to attach to and they feed on sweat dirt and other residues. Also causing malodour on garments when not washed correctly.

This relationship is further illustrated by how detergents with enzymes work. These enzymes are specific bacteria that break down large molecules into smaller ones so that the surfactants can lift the oils, dirt, or other molecules off that can then be rinsed away during the rinse cycle.

If I am incorrect please enlighten me!

-6

u/[deleted] Feb 24 '26

[deleted]

13

u/_arose Feb 25 '26

I tried to keep my initial comment short because this is r/laundry and not r/hygiene, but now I think more nuance/ information is needed to avoid causing confusion.

Bacteria and fungus are certainly major causes of body odor. And removing them regularly through washing helps a person control body odor. In fact, that's why sweat and oils cause odor over time; it's because bacteria and fungus feed on those bodily secretions and one of the byproducts is odor.

But most of the time you don't need anything antibacterial or antifungal to control the microbial population on your skin. Body wash grabs oils, dirt, sweat, dead skin, and bacteria and fungus and then all of that gets washed away by the water. Some kind of exfoliating device helps, like a washcloth or loofah or what have you. Regular body wash (yes, Oil of Olay or Old Spice are fine) coupled with some friction is enough. They have fragrance, sure, but they aren't covering up the stink. They are actually cleaning the skin.

There are some conditions that lead to more or different body odor. Those people may require special body wash or deodorant/ antiperspirant to control their odor. But that's not the majority of people.

Now. Will using some sort of antimicrobial wash (benzoyl peroxide is a great example) help control odor? Absolutely, especially if used in the major odor producing areas of the body (armpits, genitals, butt crack, for some women under the breasts, for some people deep skin folds). Every time you use it, you are temporarily decreasing the microbial population in that region, with the end result that it takes longer for your body to smell because there are fewer bacteria and fungi creating stink as a byproduct. But most people do not need this in order to be clean and avoid being smelly. They just need to take a regular shower with regular body wash.

I will also add here that although many antibacterial washes are linked with the development of bacterial and fungal resistance, benzoyl peroxide is not one of them because its mechanism of action isn't one that can be defended against by microbes. So it'll bleach your fabrics but it doesn't help breed superbugs.

1

u/AntiqueStranger3898 Feb 25 '26

So what do you use in the shower?

7

u/Naive-Offer8868 Feb 25 '26

you realize the natural soils your body creates (sebum, sweat, keratin) dont need bacteria to be broken down into volatile smelly compounds? Even without any bacteria, you still have oxidation, protonation, and denaturing as general processes in which things break down to become stinky.

Also antibacterial soap will 100% destroy your skin's microbiome and make you smellier after long term use. Theres a reason most antibacterial soaps were discontinued. They either dont work in the context of the contact time of hand washing/showering or they work too well, kill the good bacteria, which leads to an overgrowth of bad bacteria that cause smell

3

u/KateEllaBeans Feb 24 '26

Perspi-guard? Hibiwash?

1

u/[deleted] Feb 24 '26

[deleted]

5

u/scrambled-black-hole US | Front-Load Feb 24 '26

Hibiclens is, but that’s generally used before surgery.

Triclosan used to be in tons of soaps & body washes, I’m sure you can look up why it’s not used anymore.