pneumatician - 12-9-2022 at 16:30
Hi,
the best and simple recipe to make soap skin liquid gel, of around Ph 5.5. All with natural ingredients, nothing of exotic chemicals.
Maybe if a mix a acidic olive oil and sodium hydroxide looking the Ph... and stopping when reach the Ph of 5.5??? this end in a soap?? or in a
disgusting soup?
artemov - 13-9-2022 at 01:25
I made liquid lye soap from KOH and olive/coconut/castor oil quite a few times. The final pH is always around 8/9.
Lye soap is basically the sodium/potassium salts of fatty acids hydrolysed from triglycerides by the strong base.
Reducing the pH will cause the fatty acids to separate out (protonated?), resulting in a disgusting and probably unusable soap.
From what I read, however, you can use citric acid to stabilise or reduce the pH by just a bit. Exposing it to air/CO2 (curing?) will probably reduce
the pH too.
Although the skin's pH is around 5.5, alkaline soaps do not really affect the acid mantle (there's a study on this somewhere).
[Edited on 13-9-2022 by artemov]
Lionel Spanner - 14-9-2022 at 04:18
You need synthetic surfactants, e.g. sodium laureth sulphate, to make a neutral or acidic soap. Anything based on fatty acid salts becomes
water-insoluble wax/oil when acidified.