Saturday, July 25, 2009

How conditioners work...

How does a conditioner work? Okay, a little bit of chemistry for you...

A conditioning agent (like BTMS) is a cationic quaternary compound. It's a positively charged compound that adsorbs to the surface of your hair. (Adsorption means the molecules accumulate on the surface of your hair. It's different from absorption in that it doesn't penetrate, it just sits on top of the hair fibre.) This is called substantivity. This is defined as "an adsorption phenomenon by which materials that have opposing charges or like composition are more readily adsorbed onto or attracted to its surface and, once there, resistant to subsequent rinse-off." The cationic quaternary compound is hydrophobic - "scared of water" - so it will resist removal by water alone. (The more hydrophobic the quaternary compound, the less likely it is to be removed by water alone.) So the positively charged cationic quaternary compound is attracted to your negatively charged hair fibre and clings on to the surface.

Being resistant to rinse-off doesn't mean it won't come clean and cause build up; it just means it won't rinse off when you rinse your hair after applying the conditioner. It will rinse off when you wash your hair with shampoo in the future.

Virgin hair has a pH of 3.7, and it is negatively charged. The more damaged or chemically treated, the higher the pH and the higher the negative charge. This is due to an increase in cysteic acid that forms when the disulphide bonds in the hair are broken and not reformed. So the more damaged your hair might be, the more negatively charged it is. The conditioning agent is going to be more attracted to your hair and is going to adsorb more.

So if someone with virgin hair - are there any adult women who can say that? - uses an intense conditioner, she's going to see most of it go down the drain. You've got fewer places for the conditioner to adsorb due to your low negative charge, and it'll just rinse off.

Cationic quaternary compounds increase the lubricity, static control, and combability (is that a word?) of your hair. It's always a good thing to have extra moisturization in your hair, increasing the water content on the hair fibre. By increasing the lubricity, you're reducing the force required to comb your hair, meaning fewer breakages and less static electricity on the surface.

When formulating a conditioner, we want maximum adsorption and maximum substantivity to get the most out of the product. We do this by choosing a cationic quaternary compound that will adsorb to our hair, like Incroquat BTMS or cetrimonium bromide. The cationic quaternary compound is always the basis from which we work when creating a great conditioner.

We can increase our substantivity by adding a fatty alcohol, like cetyl alcohol, to the mix. Fatty alcohols increase the substantivity of the conditioner by adsorbing to the hair fibre as well and encouraging more adsorption by the quaternary compound.

And we add all the other goodies like hydrolyzed proteins, oils, butters, silicones, and so on to increase the substantivity, adsorption, and moisturization of our hair.

So let's start with the most basic ingredient - the cationic quaternary compound. I use BTMS the most, so we'll start there tomorrow.

11 comments:

Brie said...

What a fantastic post. Thanks very much :)

Caiso said...

Great post. I'm trying to formulate my own conditioner for the first time. I just discovered your blog today. All of this is so helpful!

Isis said...

why does the pH go higher when more acid is formed????

Susan Barclay-Nichols said...

Hi Isis. Cysteic acid isn't a true acid in the sense of making the product more acidic - it's an amino acid, which is a precursor to protein, and it won't make our product's pH change much. (Scroll down in the link for more information on pKa and amino acids!)

Anonymous said...

So what if you co-wash (only wash your hair with conditioner) with a conditioner that contains btms-50 and don't use shampoo, like I do? Does this mean you never wash out the btms-50 that adsorps to the hair? And isn't that a good thing? Because it means your hair is constantly being conditioned right? Why would you ever want to remove the btms-50?(I just found your blog a couple of days ago by the way and I LOVE it!). Keep it up!

Anonymous said...

Thanks for all the hard work you do of writing all these posts to share with us Susan! I'm very interested in learning to make my own conditioner and am trying to formulate my own with research...which brings me to a couple questions. I currently use a "natural" brand of conditioner but I do not see any emulsifier listed in the ingredients. It does list beeswax but I always read that beeswax is not an emulsifier. Second, this conditioner seems to detangle my hair very well and it does have cider vinegar listed as an ingredient which I'm thinking might be why? Would this be something you add to a water phase and any clue at what percentage? Again thanks so much for all the time you take to do what you do!
-J

Susan Barclay-Nichols said...

Hi J. Can you send me a list of ingredients or a link to this product? It's hard to offer information if I don't have all the details!

A conditioner has to have a positively charged or cationic ingredient to be a conditioner. Those positively charged ingredients also tend to be emulsifiers, so beeswax doesn't fit the bill in either way.

Cider vinegar might be used to reduce pH. Or it might be there for label appeal.

Anonymous said...

Thanks for the reply Susan and sorry, I should have included ingredients to avoid the back and forth :) I have been using kogi conditioner. Here is a list of ingredients from the website.

Aqua, Cocos nucifera (coconut) oil, Pinus banksiana (pine) extract, Chamomilla recutita (matricaria) flower extract, Blechnum spicant (fern) leaf extract, Urtica dioca (nettle) leaf extract, Taraxacum officinale (dandelion) leaf extract, Acetic Acid, Olea Europaea (olive) fruit oil, Curcubita pepo (pumpkin) seed oil, Beeswax, Mentha Piperita (peppermint) oil, Rosmarinus Officinalis (rosemary) oil, Leuconostoc/Radish Root Ferment Filtrate.

On the actual label it says "cider vinegar (acetic acid)". My hair dresser said apple cider vinegar is good for removing build up in the hair so thought this was why my hair detangled so nice.

I have created my own body lotion using Ritamulse from tips from your previous blog posts about basic lotion recipe and one on Ritamulse. In all conditioner recipes I see BTMS but am trying to find something more natural and including the vinegar. I assume Ritamulse is not cationic?

Too bad I didn't love chemistry this much in school...so much more fun as an adult! :)

-J

Danny A said...

Good post Susan .

Jane Askin said...

Hi Susan,
thank you for the great info on conditioners. I am wondering if it would be useful to adjust the pH of the conditioner (either using citric acid or acv) until it is between 4 and 5, closer to healthy hair or are recipes usually acidic?

Also, when you mention film forming ingredients, how do these affect the ability of hair to absorb/benefit from later styling products? e.g. I use a diy beeswax pomade full of hair loving oils, will the film from the conditioner affect its performance?And does it contribute to build up at all?

Thanks so much.

Ankita Mishra said...

Thanks for sharing the information. That’s a awesome article you posted. I found the post very useful as well as interesting. I will come back to read some more.

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