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Menthol Shampoo: Usage Rate
I am trying to formulate a menthol shampoo for personal use and found no effect at 0.3%, but it did offer cooling when I added it at 0.5%. Reading through some older posts on this forum, I found that even 0.1% should impart a cooling effect, so I am wondering if my usage (0.5%) is considered too high or if I am doing something wrong when incorporating it.
Phase A:
- Water: q.s. 100%
- Disodium EDTA: 0.1%
- Phenonip (Phenoxyethanol (and) Methylparaben (and) Ethylparaben (and) Propylparaben (and) Butylparaben): 0.3%
- Ethylhexylglycerin: 0.1%
Phase B:
- Hydroxypropyl Methylcellulose: 0.3%
- Guar Hydroxypropyltrimonium Chloride: 0.2%
- Polyquaternium-10: 0.1%
Phase C:
- Cola®Det COCO (Sodium Coco-Sulfate (and) Coco-Glucoside (and) Cocamidopropyl Hydroxysultaine): 10.2% Active
- Menthol: 0.5%
- Fragrance: 0.3%
I add the components of Phase A in a beaker with overhead stirring at 300 RPM and then gradually add the pre-mixed dry components of Phase B. After mixing, I heat Phase A (I believe this helps solubilize the preservative?) and Phase C (to dissolve the menthol into the surfactant blend), allowing Phase C to cool before adding the fragrance into it. Finally, I gradually add Phase C into Phase A with overhead stirring at around 100 RPM until fully incorporated.
Questions:
- Is my method of dissolving the menthol into my surfactant blend incorrect?
- Is 0.5% menthol too high for a shampoo? If so, how can I achieve the cooling effect with a lower amount, considering that 0.3% did not produce one?
Thank you for all of your help!
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2 Replies
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@Camel The level 0.50% menthol will sting my eyes in a hot shower, so keep that in mind. Most of the scalp-cooling shampoos use 1.0%, so you can increase to that and find success. I could not handle it but most folks can. And, yes, you are correct to dissolve into the surfactant blend. Menthol is more oil soluble than water soluble.
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Thank you so much, @chemicalmatt ! Personally, I did not have any issues with stinging at 0.5%, but the menthol odor was quite pungent, so I’m not sure how much more I would be willing to increase it before the scent becomes overwhelming. I may test it just to find out. I was hoping the fragrance would mask it a little more, but that didn’t appear to be the case.
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