Tuesday, January 18, 2011

Adjusting the pH of our products

In some recipes, you'll see the addition of citric acid or sodium hydroxide (lye) at the end to alter the pH of the product. Ideally, our products will be between 4.5 and 7 (there are few products that fall outside these areas, like cold processed soap and some moisturizers with AHAs), and the citric acid decreases the pH, making it more acidic, while the sodium hydroxide increases the pH, making it more alkaline.

For the most part, the ingredients we use are pH balanced, so we don't need to mess around much when making lotions, unless we're adding ingredients like AHAs, but when we're working with surfactants, pH is really important.

As you can see from this recipe in which I'm using new surfactants, the first result brings me to 8.6, which is far too high for a body wash. We want something around 6.0 to 6.5, so I adjusted the pH by adding 0.2% citric acid at a time. It took 0.4% citric acid to bring the pH level down from 8.6 to 6.51, which is a good level for our skin.

As a note, I found that 0.15 cc citric acid equals 0.2 grams, so if you don't have a tiny scale, there's a quick and easy way to include it in our products. 

In my facial cleanser recipe from the Iron Chemist challenge with LSB, I found the original pH of the mixture was 5.16, which is considered acceptable for our skin's pH range. But I thought it would be fun to try to increase it slightly with the failed batch. I could have used sodium hydroxide (lye) at 10% dissolved in 90% water and add it bit by bit, but I figured this could use more surfactants, so I chose the high pH surfactant decyl glucoside to the mix. 10% decyl glucoside brought the pH to 5.6, so you can see there's quite a change when you use an alkaline ingredient.

If you want to increase the acidity of your product (reduce the pH), I recommend using citric acid at 0.2% a little at a time to decrease it by about 0.9 or so. (It isn't a hard and fast rule that it will reduce it by 0.9 at a time; this was just my experience. It will depend upon the pH of your product, what kind of product it is, what ingredients you've used, and so on.)

If you want to increase the alkalinity of your product (raise the pH), you can use a 10% lye to 90% water solution and add it at 0.1%, test, then another 0.1% if needed, and so on. You can also use triethanolamine (TEA) (pH of 10 to 11) at 0.1% at a time to increase the alkalinity of our products.

Or you can use our ingredients to change the pH level. Adding something like an AHA will decrease your pH, while using a higher pH surfactant - like decyl glucoside or disodium cocoamphidiacetate - will increase the pH.

As a note, if you've made gels with carbomer, you're familiar with the idea of increasing the alkalinity of the product - add some TEA or 18% lye solution to your carbomer and you've got a gel! 

Can you tell I'm having fun with my pH meter yet?

As a final point of interest, did you know the term "pH balanced" in commercial products doesn't have a legal definition, so it can mean just about anything. It can mean "pH 5.5, which is around our skin's pH balance" to "blah blah blah". It's on par with saying your skin "appears cleaner", which doesn't actually mean your skin will be cleaner. There's a dental ad on TV right now that claims your teeth will "appear cleaner" but there's no reference point - for instance, appears cleaner than not using a toothpaste at all or another brand of toothpaste? So it really means nothing! And don't get me started on the conditioner ads that have the little asterisk at the bottom of the screen to indicate that they're comparing the state of your hair without using a conditioner (Pantene does this all the time). We all know that using a conditioner will make our hair softer and in better condition! Oh, I didn't realize I was off on a rant again...I better stop. 

56 comments:

Pam said...

Hi Susan,

What do you use to test the PH in your products?

Susan Barclay-Nichols said...

Hi Pam. I use the pH meter my mom and husband bought me for Christmas. I love it!

p said...

Hi Susan,

Have you had much luck with pH paper or pH strips? Any reason not to use those?

P

Susan Barclay-Nichols said...

Honestly, I haven't had a lot of luck with pH strips. I find they're just not accurate enough and a lot of times, they don't change colour when I know the mixture isn't neutral. That could just be the ones I've tried, but I really do like my meter better. But it's not a cheap gadget to own! I don't know how much mine was, but comparable ones are in the $90 range, not including shipping.

Rocio said...

Dear Susan

Happy new Year!!!

I hava a question.
What pH should have a 1 in 2 conditioning shampoo?

Thanks for your blog

My best regards

Pam said...

Hi Susan,

How important is to test the ph? In other words if I were to use an established recipe that had already been formulated then wouldn't the ph have been taken into consideration? Another reason for asking is the cost.

Thaks,

Pam

Susan Barclay-Nichols said...

Hi Rocio. You'd want between 5.5 and 6.5 or so. If you look at the hair care section of the blog - click here - you'll see a ton of information about making these types of products.

Hi Pam. If you are using an established recipe from a site, I would assume the pH has been tested and you don't have to worry about it. In most cases, you don't have to worry about pH in a lotion recipe, unless you're including AHAs or some acids, but you would want to check it if you're making an established surfactant based recipe and you're changing one of the surfactants (for instance).

Aesthete said...

Hi Susan, I want to increase PH in a lotion and don't have lye or TEA. Is borax suitable for that? or is there possibly something else you can recommend? thank you.

Susan Barclay-Nichols said...

Hi Aesthete! Borax has a pH of about 9.4, so it's great for increasing the pH of a product to become more alkaline or basic. The one down side is that is is known as a skin and eye irritant, so I'd be careful with it (but then again, so is lye, so you're already thinking about caution!). Baking soda has a pH of about 8.2, so this might also be an option. I'm not sure of how much to use of either ingredient as I'm not sure of the pH of your lotion, but start at 0.1% and work your way up. Keep good notes so you can replicate your results!

Bajan Lily said...

Hi there,
Can you use lactic acid instead of citric acid to adjust Ph?

Susan Barclay-Nichols said...

Hi Bajan Lilly! Yes!

Bajan Lily said...

Thanks!

Nedeia said...

How do I determine if I need to check the ph of my cream or lotion? Are there any ingredients that generally need us to adjust the ph? Is there a way to calculate the ph just looking at the recipe?

Thanks!

Anonymous said...

Hey!

First of all I need to compliment you for what a wonderful blog that is! I have learned more from here than from anywhere else ever... Really, you have done such a great job inspiring me and I believe lots of other people as well.

A question here:
Im about to formulate my own very first body lotion and looking for some good, mild for the skin, relatively natural ph adjuster that makes it all more acidic.

Is there anything else but Citric Acid you would recommend?

What about Lactic Acid? When and why would it be better that Citric one?
If there is a blog about it pls let me know!

Thank you Susan!!

K

Anonymous said...

I find that every time I add citric acid it has a bad reaction like curdling. It separates the oil in clumps and the rest is like colored water underneath the curdled clumps?

Thanks

Judith said...

Hello, I have a bag of soap from Morocco that is made from pulverized and saponified Argan nuts so it is the consistency of a very thick gel. I was told that the PH is 14. What percent citric acid should I add (per 16 oz) to bring the PH level down to about 7? Since it is a thick gel would I have to add water to dilute it in order to ck the PH? Thank you!

Susan Barclay-Nichols said...

Hi Judith. I would test the pH of that product before you do anything as pH 14 is unlikely to be the actual pH. 14 is incredibly high, on par with lye. It would burn your hands to touch it!

Anonymous said...

You're right Susan those ph strips do not work properly.
Rosi

Susan Barclay-Nichols said...

HI Anonymous. If you don't put your name on your post, I have to delete it. Please update it or I'll have to remove your post.

Anonymous said...

Hi Susan,

Just to add to the helpful starting point about decreasing pH by adding citric acid: made a test batch of body lotion and decreased the pH from 5.95 to 4.62 by adding 0.15% of citric acid which was equal to 1.7 gram for this batch. On a hand cream we added 0.7 gram which was equal to 0.07% to go from 5.86 to 5.05
So in my experience less is needed than suggested to reduce the pH in a lotion.
Kind regards, Ernie

Susan Barclay-Nichols said...

Hi Ernie. Thanks for sharing your experiences. The amount we need to reduce the pH in a product will vary for every single product every single time, which is why there's no hard and fast rule and we need to have some way to measure it. Lotion #1 might need 0.2% to go down by 1 pH and body wash #2 might need 0.3% to go down the same amount. Add a new hydrosol to body wash #2, and you'll need 0.35% to bring it down. And so on...As I say in the post, it depends upon the product, your ingredients, and your starting pH. Thanks for commenting!

cabrini brock said...

Hi Susan
Cabrini Brock

My concerns are I made my own shamppo, which the ph balance is a 9. Will it damage my hair? I did use a citric acid it bought it down to a 7, but it changed the look of my shampoo like a creamy consistent. If I add more citric acid it become to thick and seperates and than it its at a ph5 balace. I appreciate your time, hope you can help me.

Thanks

Susan Barclay-Nichols said...

Hi Cabrini! Look for the Weekend Wonderings on Sunday, August 17th for the answer. The short answer is that a soap has to be alkaline - over pH 8 - so you are changing the soap to something that isn't soap when you lower the pH. Will it damage your hair? I think it will....

Melanie said...

Are you talking about anhydrous citric acid to lower ph or any kind?

Susan Barclay-Nichols said...

Hi Melanie. Any citric acid will do. It's not about the water content of the citric acid, but its pH lowering capabilities.

Lashana Daniels said...

Hi Susan,

I want to thank you for writing this post. I have been having a hard time finding information on DIYing PH adjusting. I would like your opinion on what the PH should be for an Anti- Acne or Oily Skincare product? I read that oily skin tends to be too acidic but would you say the product itself should have a higher PH?

alexis said...

Hi! Need to check, when you say 0.2%, what is it measured against? Do I make a citric acid solution of 0.2% and add to the diluted shampoo? Or do I add 0.2% of the diluted shampoo weight worth of citric acid straight into the product? Sorry if this sounds stupid. Newbie at this.

Thanks!

Susan Barclay-Nichols said...

Hi Lashana! For any skin care products, we are going for pH 4.7 to 5.5.

Hi Alexis! The 0.2% is against the weight of the product. So if you made 100 grams of product, you'd add 0.2 grams citric acid to the mix. If you made 500 grams of product, you'd add 1 gram to it (0.2 x 500). Just add 0.2% of the total weight of the product in citric acid.

alexis said...

Hi Susan, thanks for the reply! Will try it out soon.

Cheers!!

Irene said...

Hi Susan, I am amazed at what you are doing and cannot thank you enough for your advice. There is literally no place for a novice like me to ask questions pertaining to diy skincare making. You are the answer to my problems and I have learnt so much from you.

Here is my question regarding ph adjuster:
I used lactic acid to adjust the ph of my face wash that contain castile soap,hydrosol, vegetable glycerine, aloe vera gel, and licorice extract. After using about 1% of lactic acid, I only managed to bring the ph down from about 8.9 to 7.9. Do you think this ph 7.9 still a little high for the face?

Susan Barclay-Nichols said...

Hi Irene! Yes, I do think 7.9 is too high for the face as we would really like around 5.0 to 5.5 or so. The problem is that you can't get the pH of castille soap down to 5.5 because around 7-ish is when it stops being a soap. Having said all of this, if you like it, use it and enjoy it!

Check out this post on pH and the acid mantle.
And this one on the pH of our skin care products.

It seems like every time I write about soap, I get people yelling at me for some reason. Please don't yell at me for this comment!

Victoria Stewart said...

I just want to say HI and THANK YOU! I purchased sodium benzoate from a supplier and used it at 0.5% in my lotion. It grew mold :( I searched online and found I need to add another preservative to it.
Possibly Potassium Sorbate? and then maybe Citric Acid to keep the PH at the preservatives happy place of 4. Ugh! I was almost. Almost!! ready to give up on lotion making. Thank you for this post explaining how I can both increase and decreast the PH, PLUS that there is an alternative to PH strips. Would love a link to a PH meter but will google it in a minute. Sigh. Expensive lesson learnt. Hope restored by your information. PS I've downloaded your PDF books and once understanding to make things in percentages it helped me get things to emulsify! woo hoo.
TY TY TY

Bek said...

Hello :) Im making an insect spray/graze spray and the pH is 4.9. It still stings a little and thought I would increase the pH a bit. What would be the best choice sodium hydroxide or bicarb soda? The product is water based with essential oils and just hoping by increasing the ph it may not sting as much going on.

Thanks so much in advance!

wassa said...

Hi Susan!!
I am completely new in this fascinating world of cosmetics formulation. I have been in your blog to solve some questions and I have to thank you for this helpful blog.

I would like to know if you recommend any other organic acid to low the pH. I have seen lactic acid, stearic acid or citric acid, but I don't really know what is the difference/advantage when using one or another.

Thanks in advance and Greetings from Colombia.

Nathalia

Susan Barclay-Nichols said...

Hi Bek! I'd increase it with diluted sodium hydroxide as the bicarbonate of soda isn't going to increase it by much, if at all.

Hi Wassa! Stearic acid isn't going to reduce the pH. It's a fatty acid and it doesn't reduce the pH of a product. Lactic and citric acid will, however, and either is good. I'd go with citric acid because it's chepaer!

Abdullah Sheikh said...

Iam making shampoo which chemical ph low and high ..best ph level for shampoo

Abdullah Sheikh said...

Iam making shampoo which chemical ph low and high ..best ph level for shampoo

Abdullah Sheikh said...

How percentage citric acid and sodium hydroide

Bilalahmad Shafiq said...

citric acid in shampoos 0.5 gram according to 500ml and NAOH or KOH do not exceeded 1% thats i checked in my recipe .

Susan Barclay-Nichols said...

Hi Bilalahmad. I'm sorry. I don't understand what you have written.

Sarah N said...

Hi Susan,

Love his blog!

I too, like Bek need to adjust my Ph to make it a little more alkaline.

Using 0.1 diluted sodium hydroxide as suggested, at what point should this be added?

Thanks,
Sarah N

Sarah N said...

*this!

Sarah N said...

I actually have potassium hydroxide (not sodium hydroxide), can this be used this instead?

Sarah N

Susan Barclay-Nichols said...

Hi Sarah. Yes, you can use potassium hydroxide. Add it when you have completed the product and have tested the pH. How much to add? It depends upon the pH of the product. Don't try doing this without a pH meter.

Erin P. said...

Hi there, what would you suggest adding to a baking soda/arrowroot deodorant recipe to lower the pH a bit? Would something like citric acid be appropriate for a product like that which is much thicker than a lotion or shampoo?

Sarah N said...

Thanks so much Susan. My ph meter is showing 4.2 and I was hoping for around 5.5.
Thanks again.

Sarah N

Susan Barclay-Nichols said...

Hi Erin. Sorry, I don't have any suggestions because your deodorant is likely to be a solid oil soluble bar and those don't have a pH. The best idea is to not use baking soda as it can irritate your skin. You can't reduce the pH of baking soda in a recipe like that.

Hi Sarah. Use less in your next batch! And keep good records!

madux said...

Hi Susan,

Is there a way to increase lotions PH level with baking soda or anything else easier to find? I made a lotion with 1,7% salicylic acid, and now lotion has a little lower than 3 ph level.

My local supply shops does not have sodium hydroxide or anything you mentioned above, but has Sodium Hydroxymethylglycinate(preservative) which ph is 10-12, maybe it will do the trick?

fatbustinmama said...

Help! I am making my own shampoo. I started out with a castile soap base and then learned about the PH factor in shampoo. My PH was really high. My test strips only go to 8.4 and the color was darker than that. I added 10 times as much aloe vera to see what the difference would be and it didn't change the ph level at all. Why is that? What can I do? Thanks!

Susan Barclay-Nichols said...

Hi fatbustinmama! You can't reduce the pH of soap with aloe vera. You need a stronger acid, like citric acid or boric acid or something similar. Aloe vera will do nothing except add electrolytes to the mix. Having said all that, you can't get castille soap down below about 8 without it falling apart, and our hair wants a shampoo that is less than 6, so you really can't make something satisfactory with that soap.

Sorry, there's nothing I really can help with in this situation.

Bhavika AKA Rinky!!1 said...

Hi,
I have made a lotion which has stearic acid and KOH the pH of the system is 10.2 which is too high,i used citric acid 0.3% to reduce pH to 8.0 but again after 12hrs the pH has increased to 9.3.Please help what to do to maintain the pH.or if any other suitable agent can be used to reduce and maintain the pH.
Bhavika

Lee Thulsie said...

hi Susan,

thank you for sharing your knowledge. I am hoping you can help me.....

I have made a face toner with ph3 and face wash with ph4 - can I use sodium citrate to increase ph? At what dilution? Ideally I would like both the toner and face wash to be ph 5.5.

Would a buffer solution be a better option? I've been reading that a buffer solution will help the formula be more stable and prevent ph drift. I don't have the lab tools to make a buffer solution though - can it be made without a magnetic spinner?

Thank you
Lee

Natalia said...

Hi Susan,

I'm currently experimenting making deodorant with aloe vera. I chose to use optiphen plus, but the pH range should be 3-6. While my deodorant pH is around 5,6, I want to bring it down to 5 if possible. How to add citric acid in this formulation? Thanks

Susan Barclay-Nichols said...

Hi Natalia. I can't really help you without a recipe in percentages and your process.

Kirsten Thomas. said...

Hi Susan, I know this is an old thread, and with all that has been going on up there, I don't know when you will see it, but here we go! I made a lovely facial wash, and added some apple AHA in the amount of .75%. It currently has 8% coco betaine, and 10% smc taurate cream in it. The PH (I bought a new meter...!!) says it is 4.3. I know we are usually going for at leasst 4.7 My question is, since it does have a cleanser in it, should I add a tiny bit of decyl glucoside instead of TEA, or do you think, all things in the world considered, that this is "ok" to leave for an AHA facial cleanser? The idea of it was a once a day, or a couple times a week thing. Thanks for all you do, I love your blog!! Kirsten

Susan Barclay-Nichols said...

Hi Kirsten! Sorry for the delay in responding. When you are using AHAs, you want a lower pH, so I would just leave it. You could add decyl glucoside as it has a high pH - my version from Voyageur has a pH of 11.5 - and I think that's a good idea. But I think leaving it for a once or twice a week cleanser is a good idea!