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Final questions for a palmetic/stearic shave cream blend and process
I am about to begin my experimenting this week with a cream style shaving cream (non-foam), and have a few questions now related to process.
I have researched the cream soap making process, and have some assumptions related to the cream soap I am wanting to produce. This will be a combination of stearic and palmetic acids, with water and glycerin in the final product.
The final formulation will be 45% water, 45% palmetic and stearic acid soaps, and 10% glycerin. The palmetic/stearic blend will be 70:30, palmetic to stearic.
I am basing my starting point on the document posted in the
It references 2 soaps made with a 70:30 ratio of palmetic soap to stearic soap; and also references a 5:1 ratio of Potassium Soap to Sodium soap.
My Questions:
1. I have seen referenced elsewhere on the web that the 5:1 ratio mentioned can be blended in the 70:30 mix of oils at the same time, and not a product of individual palmetic/potassium saponification, and stearic/sodium saponification. Would the correct procedure here be to blend the palmetic/stearic in a 70:30 mix and add the 5:1 potassium/sodium lye combination and let the chemistry work it’s magic?
2. At what point do you add the glycerin to a mix like this? After the saponification? When making this type of shaving cream, do you add glycerin to the trace portion of the batch? It seems the soap would need to fully finish the saponification before mixing other elements, but I don’t know if this involves fully solidifying to accomplish.
3. Is there any ingredient in the list below that would interact with LDPE or PET plastic as a container to market this in? All of the similar products I have seen are packaged in a hard plastic jar and require unscrewing a large lid versus flipping a cap to dispense. I have transferred a similar product of this formula to an empty Colgate toothpaste bottle and used it to shave in the shower, which has made it much simpler to use than the jar packaging. But, I don’t know if there is some formulation reason for doing this. (I.e.: some element etches/dissolves PET plastic…) The list of ingredients I am working with:
Palmitic Acid
Myristic Acid
Stearic Acid
Potassium Hydroxide
Sodium Hydroxide
Propylene Glycol4. Finally, is there a good starting ratio for an amount of preservatives to prevent rotting of a blend like this? The Phenoxyethanol and Methylisothiazolinone listed in the original mix are the preservatives, but is there a rule of thumb for how much is necessary?
I realize I am asking a few technical questions here that might come from a good book on this blending creams, and may even be covered in one of Perry’s courses. If so, please point me to the source and I will continue my education without bothering the groups!Many thanks!
Mark
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7 Replies
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1. Probably yes.
2. Not critical.
3. No.
4. Really depends on the final pH. If the pH is around 10 then a preservative will not be necessary. -
Thank you Belassi. I appreciate the help!
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Been there, done it… very successfully…
Your post says “cream style shaving cream (non foam)”. Do you mean non- lathering or are you talking about old style lathering shaving cream sold in tubs and lathered with a brush? If it is the latter then here are my recommendations:
It is much easier to add the glycerin in the water phase. The same goes for other additives like propylene glycol. Saponification of fatty acids happens very quickly so looking for “trace” (you’re using “cream soap” terms in a cosmetic chemisty board so be prepared for those who might not know these terms) to happen might not happen at all as the thickening of this type of product happens very quickly! My batches are done in less than 10 minutes from beginning to end of processing! Preservatives (some temperature sensitive) and fragrance can be added in the homogenization phase.
Since this soap has a “descriptive” name in front of it i.e. “shaving” then it would be covered by the FDA and as such should have a preservative. The pH is usually around 8.5 to 9.0 or so. I’ve been on the phone with the FDA so I got that info first-hand! Suttocide A was recommended by a cosmetic chemist (but is has a distinct scent that I did not like) but I have switched to one containing Phenoxyethanol. You also mentioned a term “rotting” which was originally coined by the author Thomssen and even he did see much point in leaving a formula for a period of time to get to to change consistency, so keep that in mind. Also, it will be much easier for you to work in a formula based on 100% to help you determine the correct amount of fragrance and preservation etc. that you will need!
I did a ton of research, read many soapmaking and cosmetic chemistry books, world patents and any other info I could find and have a 131 page document with experiments and observations on this kind of shaving cream so I have a great deal of knowledge and experience in this area. The amazing thing is that this is not a difficult type of product to formulate or manufacture. Finding good and reliable info was the difficult part! Special thanks to the cosmetic chemists here and other places who helped me along the way! Good luck!
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Hi David!
Many thanks for your feedback. I am making a cream style shave cream versus the brush and cup style. I have been making notes and beginning to fill up my notebook as well!
I appreciate the detailed help. I didn’t know the propylene glycol could be added in the water phase as well. I’ll try this next time. I find that I am not using a lot of it in the final mix, BUT, this last batch seemed a bit thicker than my last batch, so I am wondering if I should add a bit more next time.
Again, thanks for the help and feedback!
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New Question: I dunno if this should be a separate question thread or not, so here goes… 3 questions:
- I have noticed the last batch I made of this soap was HIGHLY effective at cleaning oil skin. I have been shaving in the shower, and when I apply the soap, I will smear it all over my face, then rinse off my hands. It takes a second or so to get it to rinse off fully, but when it does, my hands are definitely clean! Squeaky clean. Noticeably un-slick… But very clean feeling. So I am not sure why this might be happening. I have not noticed this in even the commercial bar soap I use, so I am wondering if I need to add something to the mix to soften the soap’s ‘power’? Batch consists of Palmitic and Stearic Acids, Glycerin, and water. 5:1 mix of Potassium to Sodium hydroxide for saponification.
- I have measured the soaps pH value (using the only thing I have available right now until Amazon drops off the pH meter… pH strips) and it looks to be in the 8-9 range. I noticed the current batch of this mix leaves my neck feeling a bit razor burned but not due to actual razor burn (skin is not cut up, but it has a low grade feel of that same feeling). Could this be a pH issue? At a 8-9 pH measured finished product?
- What should the target pH of a product like this shave cream be for best use? Is there such a thing as a target pH for something like this?
Such newbie questions, but I have no where else to turn for good advice!! Thanks all!
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the strong cleansing effect is most likely because you’re applying more of the product than you would with a bar soap, and also because alkaline surfactant-based products are very efficient cleaners (this is why most household cleaners are alkaline)
alkaline products also tend to dry out and irritate the skin more than acidic or neutral products, and the fact that shaving leaves the skin vulnerable will exacerbate any irritation
the pH of your final product will depend on the degree of saponification, which depends on the ratio of bases to fatty acids
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Have you measured the pH of commercial shaving creams and gels?
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