With or without Potassium/Sodium Hydroxide

Discussion in 'Shaving Creams' started by evilmojojo, May 20, 2009.

  1. Hi all,

    This is a question that perhaps not many people have thought about nor is it worth paying too much thought too. But does anyone know the key difference between creams conataining Potassium/Sodium Hydroxide and those that don't?

    I realise that all shaving products even canned goo contain alkaline chemicals which helps with the softening of the skin. Now Sodium and Potasium Hydroxide both have pH's of bang on 14 so it's pretty nasty stuff, as opposed to sodium sterate for example.

    Speik cream doesn't contain any Potassium/Sodium Hydroxide whereas Proraso does. I also have some Kappus cream (made in Germany) for Sensitive skin which doesn't either. However it seems that they all contain the Potassium and Sodium Stearate which has a lower pH of around 9-10.

    What is the purpose of the Hydroxide does it make it more effective at softening hair? I've read to beware of those chemicals becauase they make your sking go puffy and ruducing the baldes ability to cut close and once the skin calms down you are left with a less superior shave..

    If anyone knows anything I'd be keen to hear about it...
  2. From my recollection, potassium hydroxide is used for creams or liquid soaps and sodium hydroxide is used for solid soaps.
  3. Sodium hydroxide is lye. It's needed to make soaps.
  4. Which is why the shaving cream isn't straight sodium or potassium hydroxide.:tongue_sm

    It doesn't matter what the pH of sodium hydroxide is, it matters what the pH of the shaving cream is. If it is in Proraso, it's obviously OK for the majority of people, because many people use the stuff and do just fine.
  5. You have your answer. Buffer would have been an acceptable answer (although it's pH is awfully high for that--that's why they have upper lever chem courses at college) and potentially the best answer...

    Bases are slick. Don't trust me? Stick your fingers in a vat of NaOH, and get back at me dog! Or if you are a safety minded person, rub that lather inbetween your fingers. NaOH is contributing to that.

  6. I realise that it'll only be put in in extremely small quantities and will act like a pH balancer.

    But most creams do have it: T&H creams, talyors, proraso, etc.....

    The Sodium Hydroxide used in the production of Soap will react with the fats and no longer actually be Sodium Hydroxide. However it seems that some brands add it into their creams.

    So is there a hierarchy of strengths of creams? i.e. those with Potassium and Sodium Hydroxide have higher pH's and are better at softening the hairs, while Speick and Kappus have lower pH's meaning they are gentlier on the skin but not as good at softening the hairs?

    Anyway, I might be reading into it too much, it could just be the preference by certain companies to achieve the correct pH. i.e. maybe Potassium/Sodium Hydroxide are cheaper pH balancers than Potassium/Sodium Stearate cause they need less of it.

    maybe I'm looking into it too much. :bored:

  7. true bases are slick, but only because they are turning your skin into soap by disolving it. (that's what I was told back in chemistry), I don't think somehow that that's the reason why alkalines are added to shaving cream though as it is in such small quantities. Nor is it why the cream is slick, it'll be the other ingredients. I'm certain it has more to do with breaking down hair to prepare it for cutting.

    What I'm trying to get to the bottom of is why some brands chose one type of alkaline while other use another. And is there any particular advantage to either one. It seems the Germans perfer the Stearates as opposed to the Hydroxides for some reason.
  8. You can never ask yourself too many questions--educate yourself, know the options, know the potential hazards and benefits. You are doing the right thing.

    There is lots of awesome science you can learn which CAN help you understand some of the many chemical factors of your shaving cream or soap. You can find this information in an organic chemistry course--you learn about saponification and esterification, the importance of lipids in these processes, and other cool stuff. As a disclaimer, I should say that organic chemistry tends to weed out would-be med students (read: ORGANIC CHEMISTRY IS CRAZY HARD/AWESOME!!!)
  9. Boy, we keep going back an forth--things are getting a little out of order, but thats OK.

    One possibility is availability and cost. I don't know the exact ingredients of many soaps, but another possibility is how it reacts with those ingredients--maybe the NaOH isn't good, but its stearate is.

    To answer your other question, yes, the hydroxides will help break down hair, consequently softening it, and making it easier to cut. This has to do with the protein structure of the hair (keratin) and hydroxides may be better at this than stearates, but I do not know that.

    As for bases breaking down your skin, this is also true--sort of. NaOH or MeOH will react with the fatty acids and oils in your skin to undergo saponification reactions. It might sound familiar; soap and saponification are related. They form what are called micelles, which are also found in detergents and help prevent the lather and water from mixing too much.
    Last edited: May 20, 2009
  10. Don't worry about sodium hydroxide in the ingredients list. True, it is one of the initial ingredients but, in the soap making process, the lye reacts with the fats and oils and goes through a process called saponification. The end result of that chemical reaction is soap. Once the lye has completely saponified the oils, there is no lye left. Only soap.

    I learned this from my wife who taught me how to make homemade soap. It's a pretty cool process, actually.
  11. It's generally best to use products which are ph balanced to the skin or close (around 5.5 ) if possible- it's healthier. Also, consider where the ingredient is listed on the product's ingredient label. Ingredients are listed in order of predominance. So it would be better if you see alkaline products toward the end of the list.
  12. Also, the water is actually what will cause the hair to swell and soften it.
  13. When I read "Kyles post" he mentioned the purpose of the alkalinity of shaving cream is to weaken the hair thus allowing the water to penetrate it more easily.

    I've decided I'm going to go buy some pH indicaters from a pharmicist and do some experiments!!
  14. BTW, when companies, such as QED, list "saponified oils" on their ingredients list, that's a nice way of saying sodium hydroxide. That just means they used lye to turn their oils into soap. There's nothing wrong with sodium hydroxide, unless of course the soap isn't cured, in which case it can give you third degree burns.
  15. I don't think this is right. Once the oils are completely saponified, meaning that the chemical reaction with the lye is complete, there is no more lye. The chemical reaction turns the lye and the oil into soap (and it emits a LOT of heat in the process). For cold process soap (which is what my wife and I make), the reaction takes approximately 12 hours. After that, the soap is safe to touch...because there isn't any more lye. It's not like after the soap is made, there is still lye in it. If there was, using soap would cause chemical burns. During the 12 hours, however, the mixture can burn because there is still lye that hasn't yet combined with some of the oils and been turned into soap.
  16. Rudy Vey

    Rudy Vey Vendor Contributor

    Also, one of the main differences using either Sodium or Potassium Hydroxide in soap making is that the "hard" soaps, i.e. the solid ones like for soap bars, shaving soap etc., normally Sodium Hydroxide is used, and the "softer" or liquid soap formulations Potassium Hydroxide is used. I highly doubt there is any free Sodium or Potassium Hydroxides in any soaps, creams or else we are using, and if in such minute amounts that will not harm one. But, our skins are all different, and what works for one just fine, is a negative example for the next one.
  17. I didn't know any of this stuff...very interesting. :001_smile
  18. When making soap, I know that you have to be really careful about getting the right lye/oil mixture. When making soap with my wife, we use a scale that measures down to a tenth of an ounce. If we're off with the lye by even one tenth of an ounce, we correct it. The same with the oils. It has to be rather precise. If you have too little lye, not all of the oils will saponify, and the soap won't be solid. Too much lye, and you'll still have some raw lye left over after all the oils have saponified. That would lead to the aforementioned chemical burns.

    Oh, as an afterthought -- if there was ever any lye left in a bar of soap, or shaving soap/creme you used, believe me you'd know it. When making soap & handling lye, we have to wear heavy gloves, eye protection, and even (sometimes) masks over our faces. If you get even one tiny speck of lye on you, you can feel it burning. And you can't wash it off with water: water increases the reaction and will REALLY burn you. You have to neutralize the lye with vinegar. Lye is really caustic, nasty stuff. As most of us don't routinely have a need for a bottle of vinegar with us when we shower or shave, I'm reasonably certain that all of the lye used to make the soaps/creams must have been transformed in the saponification process.
    Last edited: May 21, 2009
  19. KOH makes a soap "paste" rather than a hard "bar" of soap. A mix of NaOH and KOH allows you to tune the consistency of the finished soap. Naturally you can add water or other substances to change the consistency, but KOH-based soap do better in creams so are usually a primary component of shaving cream soap.

    Not true. However, you can make soap on your bare skin, once the hydroxide burns through the outer layers down to the fat, and that would be slick. Just don't do that, okay? Household bleach feels slick too and it's not saponifying your skin's upper layers.

    Stearates are fatty acids (i.e. an oil) and are reacted with the hydroxides to saponify and make soap.

    While I can't say for sure, I think that the softening of the hair comes from (a) oil removal by the soap and (b) soaking in warm water. It's possible that a mild alkaline or acid would soften hair as well, but I don't know.
  20. No, they don't: it depends on concentration. A pH of 14 is only reached if you create a solution of 1 mol per liter---40 grams of NaOH or 56 grams of KOH (in 1 liter water). If shaving cream or soap contained that much base your skin would be very happy to let you know all about it.

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