[Stephanie]

ketchito said:

@Stephanie Could you make a sample at pH of 5, and another at a pH of 6? I believe the acidity might be modifying the structure of the emulsion. Check how they behave in the oven. 

Hi Ketchito, but I think salicylic acid won’t be active at those pH as it’s effective at quite low pH. But will try it out if have time. Thank you

[Stephanie]

MarkBroussard said:

@Stephanie

What preservative are you using … you only list preservative?  Depending on the composition, the preservative may be the culprit in the reduction of viscosity.

(1)  Add the SA directly to your oil phase.  As mentioned by @ngarayeva001 it is oil soluble, so you don’t need the premix you are preparing.  Note: why are you using both Sodium Phytate and NaOH … you only need one base to raise the pH.  Unless you’re using Sodium Phytate as a chelating agent?

(2)  Prepare the emulsion without the addition of the preservative.  If the emulsion will not form or breaks, then you know that you need to choose a different emulsifier that works with SA.  If the emulsion does form, but thins or breaks when you add the preservative, then you need to choose a different preservative.

Hi, the preservative I’m using is benzoic acid, sorbic acid. 
(1) Yes, sodium phytate is as chelating agent. Will try the method by putting SA in oil
(2) I have done the base (without EO, extract and SA) before, using the same preservative, it’s stable, thus is not preservative issue. Might be SA with the emulsifier. 

Thank you for the advice. 

[Stephanie]

grapefruit22 said:

They mentioned in the brochure that the emulsifier passed stability tests at elevated temperature in the presence of electrolytes without affecting the viscosity, but there is no information on what formulation was tested. They use acrylic thickeners in some other available formulations. Can you use Sepimax Zen?

Sorry, I can’t use Sepimax Zen, as it’s not natural

[Stephanie]

grapefruit22 said:

Q: Propanediol 2%
Salicylic acid 2%
Water 1%
NaOH 0.45%

Is this a separate phase where you try to dissolve the salicylic acid? I think @Abdullah may be right in suggesting dissolving the acid in larger amount of water. This is just an idea because I have never tried to dissolve it in such a small amount, but even in the larger amount it was quite difficult, the proportions in the other formulations suggested more water to prepare pre-solution.
What is the pH of this solution? It should be around 10. Do you add a solution with this pH directly to the cream? This can raise the ph above the allowable range for the emulsifier you are using. pH shifting can also destabilize the emulsion. If you lower the ph after adding the solution, do you do it by stirring? Lowering the pH below a certain level may cause salicylic acid to recrystallize. Your emulsifier is somewhat resistant to electrolytes, but the amount may be too high.
Generally, I think the salicylic acid may not be fully dissolved, I would try to make a pre-solution with more water, lower its pH before adding it to the cream. But this formulation seems very difficult, I would try it with an idea from @ngarayeva001

@Microformulation, several popular brands have been selling products with 2% salicylic acid in the US for years, and their labeling does not imply that it is OTC, there is no mention of “acne” in any of them. It is not like in Europe that generally 2% is acceptable, but there is a rule that you cannot suggest a medicinal effect of a product?

Based on your question, kindly refer to the below:
1. The pH of this premix is pH 4.5
2. Yes, I added directly to the cream by stirring
3. I didn’t lower the pH as the pH ald within the effective range of SA

But I have another question is did you mention that my emulsifier is unable to resistant for the electrolytes as the amount of electrolyte is too high?

[Stephanie]

Microformulation said:

2% Salicylic acid? This is an OTC product and not the best Formula for a self-professed newbie. Have you reviewed the Regs? Again, this would be an OTC Drug.

Hi @@Microformulation Yes, I have reviewed the Regs. 2% is the max to use in skin care product

[Stephanie]

evchem2 said:

 I don’t put full stock in the HLB system, but your only emulsifers have a somewhat low HLB, you could try adding in something higher to balance out. Also 5% of both of those is likely overkill, try cutting them in half. Also, how long after finishing the mix do you wait before you put the sample in the oven?

Likely unrelated to your issue, but is your vitamin E the acetate form or tocopherol?

Hi, the HLB of the emulsifier is between 8 to 10, still consider low?
After finishing the mix, I will wait for next day before put into oven. Vit E is tocopherol.

[Stephanie]

Gum is mixture of acacia senegal gum and xanthan gum
Preservative is benzoic acid,sorbic acid. pH is 4.74
Did u mean I should add salicylic acid before emulsify? I have tried, but emulsion can’t formed if I did that way.
I use ultra-turrax homogenizer.