Wednesday, April 14, 2010

Surfactants: Fatty acid isethionates

I do love the isethionates, found in the form of sodium cocoyl isethionate (SCI) or ammonium cocoyl isethionate (ACI). The sodium version comes in prills, flakes, or noodles, while the ammonium version comes in liquid form at 30% active. If you look at this picture, the M+ signifies either sodium or ammonium, both of which have a cationic or positive charge.

Fatty acid isethionates and taurides (more about those tomorrow) are prepared by a reaction of a fatty acid chloride with sodium or ammonium isethionate which comes from the addition of sodium bisulphide (NaHSO3) and ethylene oxide. Generally, the fatty acid is coconut oil, hence the "cocoyl" part of the name.

Isethionates are considered exceptionally mild for skin, hair, and eyes, and are particularly tolerant to hard water. They leave behind a great skin feel - usually described as "silky" - and create really lovely foam, bubbles, and lather.

SCI is found in a solid form - prills (like Jordapon prilled), flakes, and noodles - whereas ACI is liquid. When you are melting SCI, there are a few things you can add to increase the solubility and melting time. You can add some anionic surfactants like the alkyl sulfosuccinates, alkyl ether sulfosuccinates, sodium or ammonium taurates (see tomorrow's post), acyl glutamates, or acyl sarcosinates. You can add the amphoteric surfactants like the betaines or hydroxysultaines. Or you can add some non-ionic surfactants like polysorbate 20 or 80, alkyl glucosides (like decyl glucoside), PEG glyceryl cocoates or PEG glyceryl laurates.

My first choice is always cocamidopropyl betaine because it increases the mildness of the surfactant mix! (As a note, I'm calling it cocamidopropyl betaine instead of coco betaine because they are, in fact, two different products. It's a pain to type, but it's a good thing to be accurate!)

Granules are generally just SCI, whereas the flakes or noodles may contain stearic acid, and the noodles may contain plasticizers like oils to keep their noodle-y shape. SCI granules are generally found as prills like Jordapon prilled (they prill it so it's less dusty, but it can still get up your nose, so wear a mask!) This product is 54% active and has a pH of about 6.

SCI loves being near stearic acid - you can add a lot to it before you ruin the lather and foam - and this is the secret of syndet bars like Dove. The moisturizing comes from the stearic acid. If you have the granules, feel free to add stearic acid to it. If you have the noodles, you may already have enough stearic in there, so you don't need to add more (having said this, you can add more if you like because moisturizing is a good thing!)

If you've tried making a shampoo bar with SCI, you'll notice there are sulfosuccinates (Bioterge 804), taurates (DLS mild), and an emulsifier (BTMS). These all help to increase the solubility of the SCI so it will melt better. (See above.)

How much SCI can you use? "The CIR Expert Panel concludes that SCI is safe for use in cosmetic formulations at concentrations of 47.5% in rinse off products, and at 17% in leave on products." So if you have Jordapon prilled SCI, you could use about 88% SCI in a shampoo bar. If you have other versions - for instance, 85% SCI, then you could use about 55% in a rinse off formula and still stay in the guidelines.

SCI noodles, flakes, and prills have a 2 year shelf life. ACI (liquid) has a shelf life of one year.

SCI is great for every skin or hair type. The dry type will enjoy the gentle cleansing and the creamy after feel. The oily type will enjoy these features as well. SCI is great for a cream cleanser - the oils won't mess with the lather too much - and body washes. The down side is that SCI will make it difficult to make a clear shampoo, body wash, shampoo, or facial cleanser.

ACI is also great for every skin type. It is substantive to skin, so it offers not only gentle cleansing and a creamy after feel, but it will offer some conditioning. Oily skin will benefit from the moisturizing without oils, while the dry type will appreciate the lack of tightness. Because it's a liquid, you can create clear surfactant mixes and don't need to worry about all that melting (although you'll still want to include the cocamidopropyl betaine for thickening and increased mildness).

Join me tomorrow for fun with taurates (also known as taurides).


Lalla said...

I'm going to try adding more stearic acid to my shampoos.

Is there a difference between cocomipropyl betaine et cocoamidopropyl betaine?

Susan Barclay-Nichols said...

Hi Lalla. Cocoamidopropyl betaine is still a cationic surfactant, but it includes an amino acid in the process, which means it is slightly more gentle than cocomipropyl betaine (which is very gentle, so you're not going to notice a difference, to be honest). In all other respects, they are the same.

I have a post coming upon this topic in a few days, so watch for it!

Tara said...

Where do you purchase the SCI with stearic acid? I have SCI flakes without stearic acid. Can I add the stearic acid to SCI in a shampoo bar for my son's dry hair?

zheng hui li said...

Dear susan,
Could you kindly explain the difference between coco betaine and cocoamidopropyl betaine in term of specification and production process?
Thanks alot



eugene said...

Dear susan,
Could you kindly explain the difference between coco betaine and cocoamidopropyl betaine in term of specification and production process?
Thanks alot



Susan Barclay-Nichols said...

Hi Eugene and Zheng. No, I can't comment on that as I don't study the production of these ingredients. Sorry I can't be more helpful.

Aesthete said...
This comment has been removed by the author.
Aesthete said...

Hi Susan,

I have an issue with SCI, it consistently recrystallizes in every liquid shampoo formula I've used it in. I've also tried your SCI recipes with the same outcome. I follow formulation instructions to the tee, heat and hold and even let the two phases stay at 70c for an additional 10 minutes to get it all melted but no dice. I've been trying to figure this out for weeks and today I found this on PubMed:

Sodium cocoyl isethionate (SCI) has been a predominant ingredient in syndet bar formulation for more than thirty years. Although cost effective and well recognized for good skin compatibility, SCI is not regularly found in liquid detergent systems due to its limited solubility in water. This study focuses on the understanding of enthalpy of solubilization, equilibrium of solubilization, and the structures and properties of sodium cocoyl isethionate and various surfactants. The purpose of this exercise is to help the formulator to find appropriate surfactant systems to keep sodium cocoyl isethionate in aqueous solution. The solubility of SCI in water is unfavorable in terms of enthalpy of solvation. When setting up equilibrium of solubilization, there are three possible phases, and three methods have been developed to prevent SCI from recrystallizing in aqueous solutions. The first focuses on tying CI ions within micelles made of secondary surfactants. The second focuses on the exchange of sodium ions with ammonium ions (and/or triethanolammonium). The third centers on emulsification of SCI and the subsequent change of micelles into emulsified oil drops. A combination of two or three of these methods will enable the formulator to use SCI as the primary surfactant in liquid detersive systems.

I've been melting the SCI(5,5%) with SMC(20%) , cocamidopropyl betaine(8%), glycol stearate(2%) and sulfated castor oil(1.2%). I can't find any info on CI ions or Sodium ions regarding the secondary surfactants i'm using and am not sure if the rest of the surfactant phase is inducing or enabling the crystallization. If you have any suggestions, I'd really appreciate them. I really love SCI don't want to give up on it.

Thank you

Erika said...

Dear Susan,

I would like to find a primary, anionic surfactant, which is very safe, natural, and I could use in pure organic products. I was wondering about Mipa Laureth Sulphate, but it contains propylene glycol (if im right. im not an expert :) ), which is quite harmful..
It would be easily available for me to buy, but I dont want any syntethic thing...
Could you please help?
Thank you!

Susan Barclay-Nichols said...

Hi Erika. There are no organic surfactants you could use as they are all synthetic. You will have to use soaps for your products.

Propylene glycol isn't harmful. There is a lot of misinformation about this ingredient and others, and i really recommend you take some time to read more about ingredients.

arizona516 said...

HELP Susan,
big fan here and I'm trying to formulate my own hair product line but while I'm not going to ask you to formulate it for me I really need help. I have a couple questions. How am I suppose to know how much percent my oil and water phases are suppose to be equal to for my shampoos conditioner leave in conditioners, creme, and gel? I see people making products and sharing recipes and that doesn't really help me in making formulation of my own. I understand the basics but the hlb system is confusing. Ive made a list of the only ingredients I want to put in each one of my products (as there are ingredients i hate like fragrance, carbomer,glycerin in gels and leave on products, hydrolyzed protein, etc) but i don't understand the percents for each ingredient or where to start. I understand oil phases and water phases and heating and what not. its like theres no one on the internet making videos explaining. Also I have another question I want to make a peg water soluble silicone hair serum with oils. How can I do that without creating a cream and keeping serum texture without adding water and keeping it water soluble while still being able to protect hair from heat?

Thank you so much have a great day

arizona516 said...

Also I have a question about water soluble silicones my hair hates humectants or at least high concentrations in leave on products(makes my hair bone dry,brittle,rough) and I'm in love this idea of being to get superior combing and frizz reduction and moisture from water soluble silicones but I know that to make them you need polyethylene glycol which is a humectant. I'm fine with that in conditioners and shampoos but not in any leave on product whether in a serum or curl creme or especially a leave in or gel. would these silicones act like humectants? Thanks

Susan Barclay-Nichols said...

Hi arizona516! Have you looked at the hair care section of the blog? You don't need to use the HLB system to make shampoo or conditioners. Everything you want to know is in the hair care section! As for videos, have you checked out my YouTube page?

As for water soluble silicone serum, I don't even understand what this might be! Water soluble and silicone don't go together. Why PEGs? Why not oils?

I have no idea what you are talking about with getting superior combing and frizz reduction with water soluble silicones. Regular silicones work that way...why use water soluble ones? I encourage you to read the information on anti-frizz products and the ingredient posts for silicones as I'm not sure exactly where you got this information from, but silicones aren't humectants in any way.

Can I ask you a question? And please don't get offended...but have you even looked at my blog? It seems like you've learned quite a lot from somewhere, but it isn't the information you need to start making hair care products. I understand you want to create a hair care line, but may I suggest walking before sprinting in the Olympics? Start at the beginning and work your way forward, trying different recipes and learning what each ingredient brings to the mix. I'm sure you'll enjoy the journey a lot more if you take it in stages.

I cannot stress enough how the newbies section might help you understand what makes up each product and how to formulate them. There's a lot of information that isn't exactly right in your two comments. I can't stress enough how much you might want to go back to the beginning and learn about each product you want to formulate one at a time.

Kelli Spears said...

Hi Susan. Was just looking at the comments on this post about SCI and I saw the comment from arizona516 regarding water soluble silicone serum. Lotioncrafters sells an ingredient called Serum SE if you look in the Silicones section. It's for making water in silicone emulsions or serums and there are several formulations people can try or at least get a basic idea for creating their own formula. They all have one of the glycols listed however, with Dipropylene Glycol being the most dominant. Thought this might help arizona516 but I don't know if you could leave the glycol out??? Maybe Jen at Lotioncrafters would be of more help to her since I have never used this ingredient. It sounds like an interesting ingredient to experiment with. Possibly a leave in treatment designed for heat styling protection similar to the all silicone/oil heat treatments, but with this ingredient you could add some water soluble ingredients that you normally would not see in the all silicone/oil treatments. Certainly gets my mind going.
Might have to play with this one.
It says it will emulsify restricted amounts of fixed oils and triglycerides, so probably very minimal amounts.
Hope this helps you out arizona516.

Kelli Spears said...

Sorry for the second comment Susan but after reading arizona516 comments I also had the impression that she was new to formulating. It made me wonder if perhaps she feels that water soluble silicones are better for hair than regular silicones??? She may not be aware that while there are silicones that are soluble in water they act on the hair in the same way as regular silicones and there are people who think that even small amounts of silicones will build up on the hair and it will never wash out. Maybe this is her reason for wanting a water soluble silicone and oil serum formulation? I know you have written posts about various silicones and their functions and she should maybe refer to those posts as well.

Susan Barclay-Nichols said...

Hi Kelly! Never apologize for any number of comments when they're this good! Thanks for your thoughts and input. Unfortunately, as happens regularly on this blog, someone asks a question and never seems to come back for the answer. much work to answer comments, too....

Oh well, back to the thoughts... I just received some of this serum maker and I plan to play around with it a lot in the next few weeks. The only down side is that we have to use a stand mixer with it because it wants to be mixed for something like 10 to 15 minutes, which is a surprisingly long time to be holding a mixer!

I honestly think the original writer read something somewhere that indicated that water soluble silicones were a better thing than using regular ones and held on to it. As an aside, I've never seen that information anywhere about water soluble silicones.

Brandi Yates said...

I tried Jordapon liquid... Ammonium Cocoyl Isethionate and it is being discontinued at the herbarie.

I love it and so far, its my favorite. I think that what I am looking for is a liquid version Ammonium Cocoyl Isethionate.

Please help me find a substitute if anyone knows.

Valerie Jaquith said...

I have this habit of adding secondary surfactants to my liquid soaps (castile type). My idea is my adding things to my various castile formulas I can increase the feel and mildness of the finished product. I am just in the experimentation phase and I don't see that people do this. I am curious about SCI and thinking I might try it. Any suggestions as to how to add it to my liquid soap (guesses are fine!) are appreciated! Valerie

Susan Barclay-Nichols said...

HI Valerie. My guess is that you could melt down the SCI and add it to the soap? I don't know, to be honest. I don't make soap. Let us know how it turns out! said...

I have been trying to locate a vendor for Ammonium Cocoyl Isothinate and I am not having any luck. BASF used to handle it but not anymore (apparently) here in the USA.

I am looking for about 50-100 Kg of ACI-30


Jake said...

Could you make a cleansing bar with this and use a liquid such as aloe vera juice? What ratio of SCI to liquid would be ideal for a solid bar? Thanks!

Anonymous said...

Hi Susan! I'm trying to formulate with SCI. It seems like all or most of your recipes use the version with stearic acid. However, I only have the kind without stearic acid. Do I need to substitute somehow? For instance instead of using 30% SCI(with stearic acid) should I use 15% SCI(w/out stearic acid) and 15% Stearic Acid? I would think adding that much stearic acid would be really undesirable in a shampoo, it'd make it very thick and draggy. But if that's true, how come you don't get that effect when you use SCI(with stearic acid) in your shampoos? I would think substituting SCI(w/out stearic a.) for SCI(w/ stearic a.) would really affect bar hardness when formulating a shampoo bar(which is what I'm currently trying to make).


Susan Barclay-Nichols said...

Hi Bridget. I use the version without the stearic acid because I have oily skin and hair, so you can make the recipes without having to make modifications. If you were to add stearic acid, try 5%. 15% will be very greasy feeling and, as you point out, would make it thick and draggy.

If you were using the version with extra stearic acid, it'd only work out to maybe 4.5% of the total amount. (30% SCI in the product. Extra stearic would be 15% of the SCI amount, so you'd have 4.5% or so...) And it isn't that draggy. I have a version I'm using right now with the stearic acid added SCI and it's nice. It just leaves my oily hair feeling less than clean.

Lisa said...

Where can I buy this ingredients? I've searched all over with no luck.

Susan Barclay-Nichols said...

Hi Lisa! Check out the FAQ for suppliers near you. I buy it from Windy Point and Aquarius in Canada. There are loads of locations in the States, like the Herbarie. In England, Of a Simple Nature sells it.