Wednesday, 2 October 2013

pH in handmade soap – Shampoo bars – Citric Acid



 
Although I am okay with the pH in my handmade soap bars as it is , I am still experimenting with bringing it down in my shampoo bars.  I read a very interesting post recently on Soap Queen
claiming that they achieved a pH of 7 in a shampoo bar recipe using Citric Acid, so I decided to try it.  I am not sure if the quantity I used was correct but I got some strange seeping…
won’t know for another 6 weeks about the pH!  Will update!
Xoxoxo Jen

15 comments:

Lindsey @ Bear Soap said...

That is indeed very interesting seepage! I haven't used Citric Acid to change the Ph, but I can see why that would be good for shampoo bars. (A soaping endeavor that I have yet to master. Mine just don't work on hair. Great on hands and body, though!)

Coco said...

Oh dear. Is that your normal recipe, just with citric acid added?

Jennifer Young said...

Lindsey, Nice blog you have!!!! I will continue to experiment with Citric Acid and post again! xo Jen

Jennifer Young said...

Coco, yes, a normal recipe just with citric acid added... so I will have to experiment with quantities and methods once I feel the citric acid addition has served in some way! Will post back. xo Jen

Amy@10th Ave. said...

Aren't shampoo bars a huge challenge? I'll be interested to know what you think of them after the cure--I hadn't seen that SoapQueen post before.

Jennifer Young said...

Amy, So glad you are back!! Yes shampoo bars are a challenge and keep me hooked.... xoxox Jen

Pam said...

Hi Jen! I have actually seen on youtube no link, a woman add lemon juice to a traced soap. I tried this myself after estimating 3 percent fresh lemon juice and added this to a batch. It does feel more ph balanced but I don't have a meter. Happy experimenting.

Pam said...

Sorry I displaced 3% of water with pure lemon juice and added it at trace. Lovely soap really, not a shampoo bar but that is a good idea!

Jennifer Young said...

Hi Pam, Thank you for your ideas and comments! I have tried lemon several times in soap, lemon juice, ground up whole lemon... didn't really see a difference to the pH. Will post back about the pH! xoxoxo Jen

Diva Soap said...

I have made a soap with citrus fruits juice, in place of water (the whole amount), maybe you remember it, Jen, you commented on the post on my 'Troublemaker' blog. It resulted with no pH values chenges!
I'm so curious whether citric acid works, keep us posted!

Jennifer Young said...

Hi Maja (Diva Soap), I will post back about pH values, in both of these soaps. xoxoxo Jen

Anne-Marie said...

That is such an interesting effect! I didn't have that happen when I made my batch, so I'd love to hear if you can figure out what happened in your batch.

Tarc said...

Though I haven't made any soap by hand (yet, I'm going to be next week), my minor in chemistry might be able to help. Adding citric acid to soap should work great with M&P and well as with hot process when you add it after saponification. You can't effectively add it into cold process because the citric acid, when added before the lye is used in the saponification process) will *instantly* react with the lye, producing sodium citrate (a salt) and water - and worse, cut the lye available for saponification! Your bars will be much more superfatted, and the salt with then be hygroscopic, attracting and keeping water in the bars you want to harden. The odd effects and the weeping are due to the combination of these effects. If you'd like to change the post saponification pH, I'd instead add a pair of weak organic acids like mono- and di-sodium phosphate at a ration that's available online (and in most CHEM 101 textbooks under 'weak organic buffers'). The hydroxide will then (though a bit more slowly) saponify to completion, leaving the phosphate to buffer the soap at the desired level.

Jennifer Young said...

Tarc, Awesome for the help!!! I am not too concerned really about the ph in my bar soaps but would be fascinated to be able to play with it (something very simple in liquid soap). Not sure what you mean at the end about playing with ph, post saponification, as the bars are hard. Or do you mean at trace? Thank you!!! xo Jen

Tarc said...

First, a couple links: http://scifun.chem.wisc.edu/chemweek/biobuff/biobuffers.html
http://microscopy.berkeley.edu/Resources/instruction/buffers.html
That should help describe what I'm talking about. Probably the best way to 'play' with the pH of your soaps is by using a pair of chemicals to create a buffer, which is a team of in/organic molecules that will adjust and keep the pH of your product very close to the point that you set. The phosphate/citrate pair is closest to what I think you were interested in, and the stuff is cheap and available at places like soapgoods.com . It'd be really easy to make a lower pH bar by simply doing your saponification to completion, and then adding the buffer pair (I'd do 10x concentrate from what is mentioned - both are very soluble and you only need a little of each. The phosphate solution will not grow, but make the citrate fresh because it's potential bacteria food). Just mix them together, and then mix into the soap with the fragrance oils and superfat. For CP, I'd keep the concentration of the buffering chemicals low and add them in at light trace. They might actually slow saponification, especially if you want more acidic soap (which might be refreshing considering that most things, like some fragrances, speed it up). The buffer might tie up a bit of the hydroxide at first, but the beauty of a buffer is that it's an equilibrium reaction, so, over time, all the hydroxide will be released to complete the saponification and the pH will settle at the point you choice with the buffering chemicals. At least in theory. And the cool thing is that you should be able to choose other acids (alpha- and beta-hydroxyl) - you chose citric (citrus acid), but you could go with malic (apple) or any of the others on sale at the soap/cosmetics sites (check your local home brewing shop if you want to try the malic acid - food safe, cheaper, no shipping) and create a gentle 'peel' bar! Just keep the buffer concentration low and it should (again, in theory) work.