My Deep Conditioner thins out at pH 4 -4.5

EarthEEarthE Member
edited March 27 in Formulating

Hi All,

please help with suggestions to make my Deep conditioner stay stable. 

i made a prototype with CTAC at 0.5% took that out since i have BTAC in there (informed by my learning here) 

I also rescued Dimethicone from 3% to 2 in this current sample.

the sample thickens nicely at cool down but thins out when i adjust to pH 4-45 with Citric Acid. 

your suggestions will be highly appreciated. 

Water 84.1

Disodium EDTA 0.3

Stearamidopropyl dimethylamine 2

Citric Acid QS to pH3-4

Polyqaternium -10 (powder) 1

Cetearyl Al. ( Stearyl - 70%, Cetyl 30%) 6

Behentrimonium Chloride – BTMC. 2

Sunflower oil - 1

Wheat protein - 1

Dimethicone - 2

Phenoxyethanol - 1

Fragrance - 0.5

Ciric Acid to pH 4 - 4.5

Comments

  • In my experience Stearamidopropyl dimethylamine is not compatible with EDTA and citric acid. They form insoluble salt. 
    Check these one by one and see if they are compatible
  • EarthEEarthE Member
    @Abdullah thanks for this info. but i am more confused now as i have not been able to dig up any research material on this. I have seen several hair conditioner with SD and EDTA or SD and Citric Acid listed on the LOI. 

    do you have any suggestion as to what could replace this two to make this formula better? 
  • EDTA and citric acid is not compatible with cationics. I haven't used BTMC but it may not be compatible too. 
    Check it your self.
    Add some SPDMA and EDTA in water and heat, it will form salt and you will not be able to dissolve that salt no matter what. 

    My suggestion is this

    SPDMA   %1
    BTMC     %1
    Dimethicone %1
    Cetearyl alcohol  %6
    Preservative
    Fragrance

    Adjust pH with lactic acid or another acid
  • chemicalmattchemicalmatt Member, Professional Chemist
    edited April 1
    SPDMA will only contribute emulsification when used with an acid, and that is best done in sequence and with a weaker acid as @Abdullah suggests. Lactic, malic work far better than citric acid; l-arginine works best if you can afford it. Figure out the stoichiometry then add the weak acid to your water phase - after dispersing Polyquat-10 at RT first!  - then begin heating to 85C. At 85C add the behenyl quat then the SPDMA, cetearyl alcohol, dimethicone and cool down slowly. I'd add ceteareth-20 or beheneth-20 also, but...that's just me.
    You are good to go, if you need more viscosity add salt (yes, NaCl) in dilute solution to the batch while still warm and in small additions. Oh yeah, and get rid of the EDTA, you don't need it. Another preservative, on the other hand, would help.
  • EarthEEarthE Member
    Thanks so much @Abdullah @chemicalmatt i will make adjustments and come back with a feedback. 
  • @chemicalmatt may I please ask you to explain (or point me in a right direction for further reading), what’s the deal with cationics and citric acid? I noticed that many commercial conditioners contain lactic acid instead of citric and I never understood why.
  • chemicalmattchemicalmatt Member, Professional Chemist
    @ngarayeva001 citric acid is tribasic with three different pKa. Malic is dibasic, while lactic, glycolic are monobasic. When making an amine salt, monobasic will work without difficulty later. I've heard folks in this forum complaining when things go meshuginah when they add citric acid. Learn to use lactic acid instead. 
     
  • DavidDavid Member
    edited April 7
    @Abdullah we have made some stable conditioners with EDTA/citric acid/ cationic combination - the order of adddition is important though. @ngarayeva001 ; - the reasons may be economical or just random. Can't remember any formulation where one acid performs better han the other..
  • Thank you for the answer :) I reduced ph of a conditioner (with behemtrimonium chloride) with citric acid without visible issues before, but since I don’t run my formulas through stability tests I can’t know for sure.
  • AbdullahAbdullah Member
    David said:
    @Abdullah we have made some stable conditioners with EDTA/citric acid/ cationic combination - the order of adddition is important though.
    Can you write the LOI of one of your conditioners?
    Better if it has SPDMA
  • chemicalmattchemicalmatt Member, Professional Chemist
    @David using SPDMA (Stearamidopropyl Dimethylamine, a tertiary amine) as the primary emulsifier as @EarthE has done here you will see a HUGE difference in viscosity when neutralizing with different organic acids as I noted. For simply reducing the pH of a cationic system comprising a cationic alkly quat or cationic polymer, not a great difference but citric is most likely to disrupt as he/she observed and for the reasons stated. Also, regarding EDTA or any other chelant in cationic hair conditioners, bear in mind those act as anti-redeposition agents primarily, preservative enhancers secondarily. In the case of hair conditioning you want to encourage deposition not discourage it, right? Thus I never add chelants to hair conditioners of any formulation medium. 

  • AbdullahAbdullah Member
    @David using SPDMA (Stearamidopropyl Dimethylamine, a tertiary amine) as the primary emulsifier as @EarthE has done here you will see a HUGE difference in viscosity when neutralizing with different organic acids as I noted. For simply reducing the pH of a cationic system comprising a cationic alkly quat or cationic polymer, not a great difference but citric is most likely to disrupt as he/she observed and for the reasons stated. Also, regarding EDTA or any other chelant in cationic hair conditioners, bear in mind those act as anti-redeposition agents primarily, preservative enhancers secondarily. In the case of hair conditioning you want to encourage deposition not discourage it, right? Thus I never add chelants to hair conditioners of any formulation medium. 

    Does EDTA decrease the deposition of Amodimethicone from Shampoo or conditioner?

    Shampoo is SLES/CAPB based.

    Conditioner is cetyl alcohol, Polyglyceryl 6 distearate, Amodimethicone. 
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