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O/W emulsion at low pH
I’m making deodorant cream (O/W emulsion) for myself with alum (potassium aluminum sulphate) as active. Personally, I don’t have problems with the low pH (approx. 2.5-3.0).
For as far as I know alum is unstable under higher pH conditions.
1. Would it be ok for the alum stability to raise the pH a little, to pH 3.5-4.0 (with NaOH)?
2. Preservatives might not be necessary at these conditions, but I like to be on the safe side. Would Phenonip at about 0,5% be a good idea at this pH?
3. I’m not sure if the emulsifiers I have can handle that low a pH.
Which one would be suitable:
- GMS + PEG 100 stearate
- Polyglyceryl-3 stearate
- Glyceryl stearate citrate
- GMS + Ceteareth 20
- Polyglyceryl-6 Stearate (and) Polyglyceryl-6 Behenate (Tegocare PBS 6)Thanks in advance!
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7 Replies
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Btw: I used to make the deodorant cream by adding 5% alum to a standard lanette I cream:
- purified water;
- decyl oleate;
- Lanette SX by BASF (cetearyl alcohol, sodium lauryl sulfate and sodium cetearyl sulfate);
- sorbitol 70%;
- sorbic acid.This is what I had in mind for future preparations (I’m not particularly fond of lanette cream):
A )
Distilled+deionized water ad 100
Allantoin 0.35%
Glycerin 2%Panthenol 1%skip panthenol to avoid hydrolysis?
Caprylyl Glycol 0.3%
Alum (KAlSO4) 5%
(Should I add NaOH here to raise the pH to 3 before I add the Phenonip?)
Phenonip 0.25%B )
Glyceryl Stearate Citrate 2% -> or GMS +PEG100 Stearate 4.5%
Polyglyceryl-3 Stearate 2% —-^
Cetearyl Alcohol 2%
Hydrogenated Vegetable Oil 2%
Tocopherol 0.2%
Isoamyl Laurate 6%
Jojoba Oil 7%
Phenonip 0.25%B1 )
Sepimax Zen 0.85% (Polyacrylate Crosspolymer-6)C )
Cyclopentasiloxane/Lexfeel D5 1%
NaOH 18% q.s. -> pH 3.5-4.0??? -> stability alum, pH too high? -
Cyclopentasiloxane/Lexfeel D5 1%
NOT THAT. Please see recent posts about restrictions. -
@Belassi
I know, I still have some left and it’s for own use, I don’t sell it.
Lexfeel D5 isn’t a silicone btw, it’s a replacement. -
Oh I see, a substitute!
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speaking from experience, you’ll want a preservative to stop yeasts and moulds growing in it
out of those emulsifiers, my personal choice would be a combination of GMS/PEG-100 stearate and polyglyceryl-3 stearate (high and low HLB, plus the GMS is acid-stable)
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I always thought Arlacel 165 was an HLB of 11 and Polyglyceryl-3 stearate (I have Dermofeel PS in stock was about an HLB of 9? That is a naroow, high range.
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@Bill_Toge @Microformulation
Thanks for your help, I just made the cream this afternoon and it turned out great (for now that is). This is how I made it:A )
Distilled+deionized water ad 100
2% Glycerin
0.35% Allantoin
0.3% Caprylyl Glycol
5% Alum (KAlSO4)B )
4% GMS + PEG 100 Stearate (Tego Care 165)
2% Polyglyceryl-3 Stearate (Dermofeel PS)
2% Cetearyl Alcohol
2% Hydrogenated Vegetable Oil
6% Isoamyl Laurate
7% Jojoba Oil
0.2% TocopherolB1 )
0.9% Sepimax Zen (Polyacrylate Crosspolymer-6)C )
1% Cyclopentasiloxane
0.5% PhenonipThe final pH was 3.2 without adjusting (turned out less acidic then I expected).
I left out the panthenol to avoid acid hydrolysis.
I put the Phenonip in the cool down instead of the water- and oilphase (because of the phenoxyethanol-emulsion stability we discussed in the other thread).
Next time I make it I’ll raise the cetearyl alcohol just slightly I think, for the rest viscosity/consistency is fine. Now I hope it remains stable for quite a while.
Until I can get my hands on a stable salt like aluminum chlorohydrate, alum works just fine for me!
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