Saturday, August 16, 2014

Acidifying Liquid Soap (Lowering pH) ..and Dove

I'm sorry I haven't kept things going with a new post.  Especially since this blog is in it's infancy.  Lots going on lately on the home front.  Plus, I needed to the motivation to pick a topic.  So, I guess I'll just dive right in.

Many fellow soapers ask about lowering pH in soap to make a milder soap.  To me, that is music to my ears.  It means they understand that the high alkalinity of hand crafted soap is in fact, harsh on the skin.  Dove had the right idea, any many scoff at it because they create hybrid soaps.  I guess, since I went there, I'll go over this "debate" as well
This post has me killing 2 birds with 1 stone it seems.

Dove is soap. Yup. I said it. And to MANY, that is blasphemy. Ok, so let's try, hybrid soap.  But to the chemistry minded soap maker, or in the least, one that knows how to read and research ingredient labels, it's truth.  So let's get right into it an analyze an ingredient label, shall we?
Sodium Lauroyl Isethionate, Stearic Acid, Sodium Tallowate or Sodium Palmitate, Lauric Acid, Sodium Isethionate, Water, Sodium Stearate, Cocamidopropyl Betaine, Sodium Cocoate or Sodium Palm Kernelate, Sodium Chloride, Tetrasodium EDTA, Tetrasodium Etidronate, Maltol, Titanium Dioxide (CI 77891).

This is Dove's basic beauty bar.  Unscented, for sensitive skin. I know many a soaper that get the comments from (non) customers who say they can only use Dove, or it's what Doc recommended.  But take a look at the ingredients.  What do you see?  I see plenty of soap ingredients in this list. Stearic Acid, Sodium Tallowate(Tallow), Sodium Palmitate(Palm Oil), Lauric Acid, Sodium Stearate(Stearic Acid), Sodium Cocoate(Coconut Oil), Sodium Palm Kernalate(Palm Kernal Oil), Sodium Chloride(Salt).  All very normal ingredients used in a basic bar of soap.  We all recognize the oils, the Stearic and lauric acids are both used as acidifyers, lowering pH.  Stearic provides a harder bar, and lauric provides bubbles and cleansing, and possibly a harder bar as wellBoth are fatty acids found in any of the oils found on this panel. Salt is also used to create a harder bar.  Out of 16 ingredients (or 14, depending on how you count the pairs with "or" in between), 9 max are used in hand crafted soap. I didn't even consider the titanium dioxide as colorant, and of course water which would bring it up to 11. That's 50% in soap making ingredients by count! 

Now let's look at the other stuff:

Sodium Lauroyl Isethionate: a sodium salt of the lauric acid ester of isethionic acid.   The Isethionic Acid is a rough one.  When cross referencing this, it is considered an "organosulfur compound" (sulfur) that is found in all things and is essential to life.  From what I an understand, it's obviously not a fatty acid combined with lye to create it salt counterpart.  The Lauroyl is converted lauric acid in this.  This is considered a very mild detergent surfactant.
Sodium Isethionate: See above^^ 

Cocamidopropyl Betaine- simply put, a coconut oil derived using the lauric acid group of fatty acids hence the coco- prefix. There's more to it than just this, but that requires TONS of cross referencing. This is however, considered a very mild surfactant, and is a replacement for cocomide DEA.
Tetrasodium EDTA: A chelating agent. It binds metals in soap when in hard water, thus "creating" soft water, and a more effective cleanser with no residue.  Pretty simple

Tetrasodium Etidronate: another chelating agent.

Maltol: naturally occurring organic compound found in larch tree bark, pine needles and roasted malt.  It's considered a flavor and aroma enhancer.

So, after breaking down that ingredient list, what do you see now?  Mostly soap making ingredients, as noted earlier.  You'll notice that the first ingredient is the detergent.  And for those who understand ingredient label regulations, they are listed from greatest to least.  That does not mean that the first ingredient is more than the combined total of the soap making ingredients that we recognize.  According to the FDA, soap can only be considered such when the bulk of it's cleansing properties are come from fatty acid salts of volatile substances ( that's not an exact quote, but I think that's pretty close).  It would appear that this is a big possibility. But, unless Dove releases it's percentages, we'll never truly know.  Hence why I consider this a hybrid soap.  But, the point of this was to show what went into Dove, to have a better understanding of WHY customers, and Docs, say what they say when they mention it.  It's its pH.  Dove have been considered a mild, pH neutral alternative to harsh ol' handcrafted soap for decades. Containing 1/4 moisturizers ta boot!! Before ya'll scoff at that as well, you might wanna take a look at that ingredient list again. I note quite a few instances of superfatting in it.  But that pH! Man!  We all wonder how.  Well, Dove uses fatty acids; lauric and stearic, to acidify the soap.  Salt and stearic to harden.  And to make sure the soap bubbles and creates a creamy lather, 3 mild detergents to round it all off. With 2 chelating agents to make sure it works well in all types of water, as well as help preserve by preventing oxidative rancidity.

So, we're back to, how do WE do it?  Without the detergents.  Good grief, do I have a lot of testing on that.  Hopefully I can summarize in a manner the reader can understand. 
I've attempted 3 methods of acidifying 8oz samples from a batch of Glycerin Method Castile LS.  I've noticed Castile to be quite temperamental in the tampering department.  So I figured, if I could do it with this, then other soaps would be a breeze.  Hopefully..

1. Combination of Citric and Lauric Acids
3.Potassium Citrate 
1. So far, my most successful attempt.  We know all about citric acid, but I chose to pair it with lauric acid for these reasons:  it dissolves in hot water (or soap) and maintains a clear solution.  Lauric acid is the primary fatty acid chain in coconut oil soaps that provides bubbling and cleansing.  It also acts as a mild thickener.  Sadly, this as a whole didn't have any bubbles.  But it cleaned well and left my skin feeling soft.  No itchiness like i experienced with it higher pH counterparts.  Used in my hair; well, I have a oily scalp.  But those oils don't migrate south.  So my actually hair away from the scalp is somewhat dry, and loved the soap.  But it was too much for my scalp.  I used it in my 2 year old son's long, blond hair.  Perfect!  No conditioner needed to help comb his hair after his shower.  For more details to this,  check out my video here.  It's pretty long and silly at times.  I try to not be too serious. But I figured if I was going to share this info, I needed proof of what I've done.  In the end, I attained a pH of 7.56. This is something I would consider a wonderful, mild all over baby wash.  Low cleansing, light moisturizing.

2.This one did not please me at all.  In short, I needed to superfat around 40% to lower pH.  And even then, I couldn't attain neutral, as I hit a plateau point around 8.5, so I had to use a small amount of lauric acid to finish it off. Final pH was 7.41.  It did not feel good in the hair at all.  Not on my son's hair either.  You can find further details here.

3.  Would not work.  I based this experiment on this. To summarize, You pair citric acid with KOH, creating potassium citrate, to prevent the acid from breaking down the soap, but still gaining the ability to lower pH.  At first I tried making it myself, slowly titrating citric acid into a potassium hydroxide solution until my phenol-p drops were no longer pink, and recording weights to attain appropriate amounts for resizing and such.  I also verified neutrality using my pH meter, just to err on the side of caution.  I could barely break under a pH 9.  So I scrapped this, assuming I was flawed in using hydroxide with citric acid rather than a (bi)carbonate counterpart as my research indicated.  I purchased a potassium citrate powder on Amazon and tried again.  With this, I just dissolved the measured powder in the heated soap.  I received the same results.  Utter failure.  Potassium citrate does have a good purpose in soap making however.  So I don't feel it's a waste of a purchase.  It's a chelating agent. It also had the ability to thicken the soap, but did have it's own limits, to which the soap thinned at a certain point.  I ended up dropping the pH with lauric acid and calling it quits.  That soap seems pretty nice on m hands but I haven't tried it on my son yet.  Which is most important to me.  I know I'm horrible for using him a my guinea pig, but I wouldn't do it if I didn't think it was safe. ;)

I didn't bother with citric acid alone since we all know that's quite effective, and could be placed under attempt #1 above.

I've also found that sodium lactate, used by many soap makers to create a harder bar overall, thus facilitating earlier cutting, and makes Hot Process soap more fluid for pouring in the mold, is also has the ability to acidify, though it would seem it requires a considerable amount to do.

Now, the biggest arguments I as an LS maker come across is, what about the free fats that result in this?  Well, simply put, use a solubilizer.  There are many on the market available to the home formulator.  So it's a matter of finding out which one is effective for your recipes, and suits your overall needs.  In my first video, as linked above, I used Polysorbate 80.  It didn't produce the clear soap I wanted, sadly.  In the second video, it was a combination of polysorbate and the sugar solution I used to maintain water concentration and weight. That produced that beautiful, clear soap..that I hated.  I chose polysorbate for it's cost effectiveness and ability to get the job done.  Which was to solubilize free fats and prevent separation.  I just recently purchased EcoCert solubilizers (caprylyl capryl glucoside) to test out.  But for the experiments at hand, I didn't want to waste such pricey ingredients.  What bothered me also about experiment #2, is the fact that generally, a solubilizer has to be paired in equal parts to the oil amounts used.  Remember that 40%?  Equal parts to that.  Nope.  Won't even do that with my EcoCert solubilizer.  But!!  With all this said, you can superfat your LS and have a truly luxurious liquid soap. I do plan on conducting some comparisons with a few solubilizers.  There is NO information as to how they behave in LS.  Not even from suppliers themselves.  So, it's high time someone does it. I'll do a short entry on that at a later date. But until then, here's a link on what you can look forward to if you give this a try yourself.  It does take some work and experimenting. Patience is certainly a virtue when making liquid soap.
What I may personally do is combine a light superfat of 10% with citric acid and see how that feels.  I'm unsure.  There's a lot of potential with this idea that hasn't been explored yet because of the common misconceptions and lack of hands on information. All in all, it IS possible to do this.  Even in the book, Scientific Soapmaking, by Kevin Dunn, acidifying soap is mentioned. But could only be done after full saponification has happened. Which is perfect for LS, and Hot Process soap in general. Or for folks who don't mind rebatching their Cold Process. And I've had many soapers tell me the get pH neutral CP soap regularly.  So, I dunno.   He sadly didn't cover the subject in detail and I haven't gotten any responses to my inquiry about this in his Caveman Chemistry soapmaking forum. 

All in all, this is forever a work in progress.  And for this particular topic, as I make new discoveries, I'll do my best to update here.  For those of you that happen to have something to add, please do. It's always nice to learn something new.  And always better that we all share so we can advance the soap making craft with quality products, for in the home, and for those who sell.