Formulating Liquid Soap

[Soapprentice]

So, all the liquid soap experts, I have a question, well not ‘a’ but here they go.. can we use the same formula we have for solid soap for a liquid soap? does too much coconut oil result in drying an issue? As glycerine is added too... we look at hardness, drying and lasting in solid soap, what do we check for in LS?

 

[DeeAnna]

"The numbers" don't relate as well to the properties of liquid soap as they do to bar soap. The cleansing number (% of lauric and myristic acids) is the only one that I think relates to LS. When I want to look in more detail at the properties of a LS recipe, I usually check the fatty acids.

Yes, too much coconut (the % of lauric and myristic acids, to be more correct) can be drying. LS recipes for bathing and hand washing often have a little higher % of coconut than bar soap to get the lather going, but that's not a universal thing, just a tendency. Some people make a 100% coconut liquid soap for laundry or household cleaning -- I think Susie does -- but folks say their hands get pretty dry without gloves.

Another issue with LS is that one squirt contains quite a bit of soap -- much more than you'd get from rubbing a bar of soap. More soap, however mild it may be, means more cleaning power and that can mean dry skin too. And it also means more soap down the drain. One way to control over cleaning and waste is to dilute the soap enough to use it in foamer bottles.

Yes, you can theoretically use any bar soap recipe to make a liquid soap, just recalculate it for KOH. There are reasons why you might not want to, however.

If clarity of the LS is important to you, you need to reduce the % of palmitic and stearic acids in the recipe (lard, tallow, palm, butters) as low as is reasonable. Also avoid fats that have a high % of unsaponifiables -- avocado, jojoba, etc. If clarity isn't a goal, then ignore what I just said.

Castor is often used in a higher % for added clarity. The Irish Lass - Carrie recipe that is pretty popular calls for 10% castor.

Keep the oleic acid around 50% give or take if you want to have a honey thick soap from dilution alone. Too little oleic acid, and the soap will almost always be thin and a separate thickener is required.

Too much oleic acid and you may have to add a lot of water to get a pourable product -- many high oleic soaps like to stay in a jelly form. In that case, the final diluted product may have so little soap in it that it won't perform well.

For your first batch, you really can't go wrong with IL-Carrie recipe. Here's my take on this recipe:

Olive Oil 65% (can substitute part or all of this with any high oleic oil like HO safflower, HO sunflower, avocado, etc.)
Coconut Oil 25%
Castor Bean Oil 10%
Superfat 3% or lower

Lye concentration 25% (water:lye ratio of 3)
Use all KOH as the alkali
If you don't know the KOH purity, choose the 90% pure option if using Soapee or Soapcalc

Can use all water to make the soap or can use up to 2 parts glycerin to 1 part water.
I have used 1:1 glycerin:water, 1:2 glycerin:water, 2:1 glycerin:water, and all water to make this and other LS recipes. They all work.
I do not recommend using the 100% glycerin method for safety's sake.
I recommend using distilled water, not drinking water.

 

[Soapprentice]

Thank you so much Deeanna... you covered all the doubts n wants..

 

[BattleGnome]

Beyond what DeeAnna just said, use the coconut amount that you use for a bar soap. My first batch was the IL recipe to make sure I didn’t screw up too bad. My only complaint about it was that it uses 5% more coconut than my skin tends to enjoy and I could feel it. I used something closer to my usual bar soap recipe for my next batch and my hands are doing much better.

 

[DeeAnna]

I agree with you, BattleGnome. I sometimes use my LS for making wool felt, and if I use the IL-Carrie recipe for doing felting, my hands get pretty dry and ashy by the end of a felting project -- usually 3-4 hours of wet soapy hands. The lauric-myristic acid for that recipe is about 17% and the oleic acid is about 50%.

I made a LS with 70% lard that has a lauric-myristic acid content of about 9% and oleic acid at 30%. Even though it is not clear and tends to separate (nope, it's not fatty acids, it's the soap -- I tested for that), my hands are much happier when I use this LS for felting.

Just musing -- This lard LS is nicely thick even with the lower than ideal oleic acid content. I suspect the palmitic and stearic acids from the lard are contributing some to the thickness along with the oleic acid.

 

[Soapprentice]

i have a very dry skin and can tolerate only 10-15 CO.. so, will replacing a bit of CO with avocado or Shea work? I’m not concerned about soap being clear but would love the pearly sheen

 

[DeeAnna]

I want you to think this through rather than me just answer your question -- Compare the fatty acids in coconut oil with those in avocado oil and shea butter. Do avocado or shea have lower levels of lauric or myristic acids compared with coconut oil? If your goal is to lower the amount of those fatty acids (in other words, you want to lower the amount of coconut oil), does it make sense to sub avo or shea for some of the CO?

 

[ngian]

Can use all water to make the soap or can use up to 2 parts glycerin to 1 part water.
I have used 1:1 glycerin:water, 1:2 glycerin:water, 2:1 glycerin:water, and all water to make this and other LS recipes. They all work.

Thank you for your great post DeeAnna!

I want to ask you about the different amount of glycerin that you have tried to make liquid soap with.

I am always using the 2:1 glycerin:water amount (while KOH solution is very hot) and the time that the ingredients reach the paste stage is around 10-15 minutes with moderate usage of the stick blender.

If lesser amount of glycerin is used (1:2 glycerin:water) will the time to reach the paste stage be relatively longer?

I will try this amount someday because I feel that the more glycerin is used the more suds are hindered...

 

[DeeAnna]

It does take a little longer as more water is used. I agree with you that glycerin does reduce the lather to some degree, so I think the trade off is worth it.

When I use mostly or all water to make the paste, I like my initial soap batter temp to be about 170-180 F (78-80 C). To get that, I warm the fats to that temperature and use hot KOH solution. Except for that initial warming, I use a cold process method -- no crock pot, no extra heating or cooking, stick blend a little bit every few minutes until the batter is at a stable emulsion. When at trace, then cover the pot and walk away.

The last all-water batch I made (this past March) was zap free in under 45 minutes per my notes. I wasn't hovering and zap testing every 5 mins, so the paste could have been done even earlier, but I don't know that. All I can say is it was fine at 45 mins. That's not too shabby, IMO.

 

[DeeAnna]

"...would love the pearly sheen..."

I don't think LS made with some avocado or shea will look very pearly -- my bet is the LS will just look cloudy, like a teaspoon of milk in a glass of water.

Irish Lass has shared a pearly LS recipe and tutorial here on SMF. She's adding extra stearic acid and other goodies to get that pearly look.

 

[Soapprentice]

I want you to think this through rather than me just answer your question -- Compare the fatty acids in coconut oil with those in avocado oil and shea butter. Do avocado or shea have lower levels of lauric or myristic acids compared with coconut oil? If your goal is to lower the amount of those fatty acids (in other words, you want to lower the amount of coconut oil), does it make sense to sub avo or shea for some of the CO?

I understood where you are coming from and thank you for making me research... I learned a lot from it. I have coco betain with me and as it is surfactant can that be used for cleansing and foaming and reduce the CO to 15( as that is how much my skin is comfortable with in bar soap). I know that avocado and Shea does not have fatty acid profile similar to CO but I also don’t have access to babassu oil and Dont want to use palm kernel flakes. I hope you understand my dilemma .

 

[Susie]

I understood where you are coming from and thank you for making me research... I learned a lot from it. I have coco betain with me and as it is surfactant can that be used for cleansing and foaming and reduce the CO to 15( as that is how much my skin is comfortable with in bar soap). I know that avocado and Shea does not have fatty acid profile similar to CO but I also don’t have access to babassu oil and Dont want to use palm kernel flakes. I hope you understand my dilemma .

If you are not worried about clear soap, then try it! We know it won't be clear, but that should not stop you from trying those substitutes! More is learned by going off the path than staying on it. Please let us know how it turns out!

 

[Saranac]

I have coco betain with me and as it is surfactant can that be used for cleansing and foaming and reduce the CO to 15( as that is how much my skin is comfortable with in bar soap).

Recently, I've been experimenting with adding synthetic surfactants to liquid soap, and I like the results. My goal is to produce a more mild product through the use of less coconut oil, and through the mixing of surfactants with different ionic natures.

Using less coconut is easy--just use less. As was noted in a previous post, a squirt of liquid soap tends to apply more soap to the skin than a bar, and as a result, the product can seem more cleansing (than a bar with the same FA profile). Reducing the coconut will help, but it also decreases the lather. Additionally, I find that LS is less quick to lather than a bar, and the thicker the soap, the harder it is to work it into a lather (at least, in my experience). The sum of all that, is that a product with less coconut may clean, but is not easy to use (and provides few of the sensorial aspects that I have come to expect). That is, unless you use a thin soap and a foamer bottle (my preference for hand washing!), or introduce some synthetic surfactants.

In spite of the scare-mongering around the internet, surfactants don't have to be scary, and I'm pleased to hear that you have some on hand and are willing to try it in liquid soap; a small amount of surfactant may go along way towards making your end product more mild and more easy to lather.

Generally speaking, mixing surfactants of different ionic natures (cationic, anionic, non-ionic, amphoteric) is a good thing as it produces a milder product. Recently, I've been mixing liquid soap (anionic) with coco glucoside (non-ionic), and my observation is that the resulting product is more mild on my hands (I have not tried it in the shower yet; maybe today), it lathers quicker and is thicker. I was able to manage all of this with just 6% coco glucoside (and 24% soap, 10% added glycerin, 60% water). I'd also like to note that the only LS I have on hand right now is formulated with 29% coconut. It's more than what you want to use, but it's important to note that even with that high amount, the product is more mild with the addition of a non-ionic surfactant.

This net result of a milder product ( I believe) only works with mixing different ionic strengths of surfactants. I assume that your coco betain is cocamidopropyl betaine; if so, it is an amphoteric surfactant and as a result of the pH of soap, will be negatively charged when mixed with liquid soap. I don't know enough of the chemistry to know if that makes it "anionic," but my thought process is that it won't be as mild when mixed with soap as it would be if mixed into an acidic solution.

With all that said, I say give it a try! Start small and if you don't get the results you're looking for, look at a different surfactant; I'd recommend something non-ionic. Unless you have one on hand, I'd stay away from the cationics; I once tried using a cationic conditioning ingredient (polyquat 10) in liquid soap and while it left a great skin feel and thickened the soap better than anything else I've tried, it STUNK, and eventually produced some sort of light sediment. Sediment I can live with--but not stink.

 

[Soapprentice]

Yes, I mean Cocamidopropyl betaine and I don’t have any other surfactant on hand. I will give it a try and let you know.

 

[Saranac]

I'd love to know what you think, so please keep us updated. I made some paste yesterday with 20% coconut and once it's diluted, I'm going to do more experimenting with the coco glucoside. I have some cocamidopropyl betaine, and I'll give that a try as well.

I used the soap-surfactant blend (that I posted above) in the shower yesterday and while it was less irritating than a 30% coconut soap without surfactant, it was still too much for a bath soap. Another thing that I failed to mention in my last post is that the concentration of cleansers in your final product has a huge impact on perceived mildness. Less surfactnat (or soap), the more mild the product. I'll admit, I love the idea of making really thick and concentrated liquid soap. . . but once I lost my emotional attachment to achieving that goal, I realized that it's just too harsh for more than an occasional handwash. Don't underestimate the value of thin soap in a foamer bottle, or thickening a less concentrated soap with HEC

 

[Saranac]

Yes, I mean Cocamidopropyl betaine and I don’t have any other surfactant on hand. I will give it a try and let you know.

The short of it--DON'T DO IT!

The long of it--

Okay--I tried mixing the LS with cocoamidopropyl betaine. The liquid soap was made with the glycerin method and a KOH concentration of 33% (1 part KOH, 1 part water, 1 part glycerin). The oils were 10% castor oil, 20% coconut, 70% HO sunflower. I diluted the soap paste in distilled water so that I had an actual soap content of 30%. Once it was nicely dissolved, I added 25 g of cocoamidopropyl betaine (30% active) to 100 g of liquid soap. The results--

It thickened--a lot! You can turn the container upside down and it doesn't move. I would assume that less of the cocoamidopropyl betaine would produce a more managable product, but there is another problem. In a previous post I wrote--

I'd stay away from the cationics; I once tried using a cationic conditioning ingredient (polyquat 10) in liquid soap and while it left a great skin feel and thickened the soap better than anything else I've tried, it STUNK

Well, my hypothesis proved correct and this stinks, and it smells just like any other cationic ingredient--that fishy odour that many people smell when using BTMS and other cationics. From the research I've done, this is pH related, and since you can't lower the pH of soap, I'd take cocoamidopropyl betaine off the table (as well as other cationic ingredients).

I also mixed the same amount of soap with 15 g coco glucoside (50% active), and it's a great thickness for a body wash or similar gel-type soap. The problem is that it's too concentrated, so I still have some work to do getting the concentration down while maintaining the thickness.

 

[Soapprentice]

Thank you so much... I will defined get another surfactant for the soap and try.. thank you for the heads up.

 

[Saranac]

You're welcome. And I'll say, it's too bad that the soap and cocoamidopropyl betaine stink so bad. Once I watered it down to a usable consistency, I held my breath and lathered up my hands; it's a great soap. Unfortunately, I haven't come across anything that would mitigate the smell. I tried a number of times to cover the smell with fragrance oil when I mixed polyquat 10 into soap, but all it did was turn me off to that particular fragrance.

 

[Soapprentice]

So, in the mean time of the surfactants’s delivery, I want to make IrishLass’s GLS.. I read that thread as DeeAnna suggested and I am not able to find the glycerine amount.. am I missing it?

 

[Susie]

So, in the mean time of the surfactants’s delivery, I want to make IrishLass’s GLS.. I read that thread as DeeAnna suggested and I am not able to find the glycerine amount.. am I missing it?

You use either an equal part of water to mix with the KOH, then the remainder of the water amount as glycerin added into the oils, or equal parts water and glycerin. Again, the water mixes with the KOH, and the glycerin goes into the oils. Keeps you from having to heat the glycerin. But the amount of glycerin depends on the water amount in the recipe.