Soap pH range - Chemists Corner

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Soap pH range

Posted by Abdullah on August 12, 2020 at 5:19 am

At what pH range soaps can be made?

Dr_Sara replied 4 years, 3 months ago 4 Members · 8 Replies
- soap
8 Replies

zetein

Member
August 12, 2020 at 5:37 am

The pH of soap-based paste facial cleansers manufactured by Estee Lauder, L’oreal, Uniliver, Johnson & Johnson, Shiseido, are all higher than 9, most are higher than 10.
So I guess maybe there really isn’t anyway going lower than that, if a stable, foamy, cleanses-good soap is desired.
Dr_Sara

Member
August 13, 2020 at 3:12 am

Soap made with oil and hydroxide yields a product with a final pH between 9 and 10 (after completion of saponification).

What is the pH of your soap?
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zacchaeus

Member
August 13, 2020 at 4:04 am

@Abdullah it varies depending on the type of soap you’ll make. Opaque soaps usually has a range of 9.5 - 12.0. While transparent soaps has 8.7-9.5
Abdullah

Member
August 13, 2020 at 4:07 am

@zetein thanks

@Dr_Sara i make liquid face wash and haven’t made soap yet.
I asked if it is possible to make soap at pH 6 or below
Dr_Sara

Member
August 13, 2020 at 6:28 am

HI @Abdullah
You cannot make soap that is pH6 or below. You would do better using a detergent if you want a low pH.

If you make soap with NaOH and coconut oil, you get sodium cocoate. If you add an acid, the sodium is replaced by hydrogen (sorry chemists, not very academic terminology) and you end up with an acid and lose the soap. The pH is lowered at the sacrifice of the soap/bubbly bit.

maybe a good example is the following
sodium stearate (soap) vs stearic acid

My soaps are around pH 9
@@Dr_Sara needs a coffee…
zacchaeus

Member
August 13, 2020 at 8:05 am

Abdullah said:

@zetein thanks

@Dr_Sara i make liquid face wash and haven’t made soap yet.
I asked if it is possible to make soap at pH 6 or below

@Abdullah what exactly is the product you want to make? Is it liquid facial wash such as Ponds from Unilever?
Abdullah

Member
August 16, 2020 at 3:37 am

@zacchaeus i am currently making faces wash with SLES and CAPB.

What about pH of Shampoo bar? Does it need to be high too?
Dr_Sara

Member
August 16, 2020 at 10:12 am

If you make a shampoo bar that is soap, the pH will be high. These formulations are historic- before the availability of detergents. Personally, I do not like the way they make my hair feel. Soap-based shampoo bars are very popular with consumers limiting their plastic consumption.

If you make a shampoo bar with detergents (ie sodium coco sulphate shampoo bars), you can lower the pH. Some add acid in various forms- citric acid, vinegar… I prefer these shampoo bars.