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There is no emulsifier in a classical meaning. The product is a dispersion of oil phase in water phase. They use C12-22 alkyl acrylate/hydroxyethylacrylate copolymer polymeric thickener to achieve this. They thicken water and oil droplets have no possibility to move around and join together -> separate.

Not all thickeners can do this. For example Gums are not good for this. Mostly polymeric thickeners (like Sepimax Zen or Lecigel) are suitable.

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For best stability of Urea you need pH 5.5-6.0. Vinegar is acidic and will drop it much lower.

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Are you sure that was NaOH and not baking soda?

If so, probably because dissolving NaOH heats water a lot. That’s why it is suggested to dissolve it in cold water in ice bath

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will this work to moisturize skin?

I don’t think we can give you skincare advice because this is a question to your esthetician.

But we can give you feedback on the formula.

1. You have a lack of water thickener (in original product it is Xanthan Gum). It affects texture and stability.
2. You don’t disclose which preservative you are going to use, so 1% might be too high or too low depending on specific blend.
3. You want to add Vitamin E which is a broad name for several ingredients (Tocopherol Acetate, mixed Tocopherols, Tocopherol). Note that original product uses specifically Tocopherol Acetate to preserve oil, not every Tocopherol-like ingredient can do this.
4. They use different emulsifying blend (Glyceryl Stearate + Stearic Acid + Cetearyl Alcohol and ). You want to use Emulsifying wax NF, which is Cetearyl Alcohol and Polysorbate 60. And on top you want to add Cetyl alcohol. Therefore the final texture will be creamier, while original product is probably waxier/harder (due to Stearic Acid). It is fine if it’s your intention.

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It is another gimmick web site that tries to sell you products by using fear-mongering as marketing. It is obvious when you see “paraben free” badges (no scientific resources will say parabens are bad) and “trusted choice” badges (most likely they take money from manufacturers to assign this badge).

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Also, there is no such thing as “allergy free” skincare, because people are so unique that there are even people, who can develop allergy to plain water. That’s why there is no “allergy free” skincare. Correct term is “hypoallergenic” (which they also use) which mean products that do not contain common strong allergens (like citrus fragrances). But to you as a specific person this means nothing because you might have no allergy to strong allergens, but have an allergy to some regular ingredient like glycerin.

You must realize that all skincare on the market is SAFE. Personal sensitivity is PERSONAL, so the website is no help to you, you have to know your own allergens by tries and errors.

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Are you sure 1,2-Hexandiol is a sole preservative? To me it seems that 1,2-Hexandiol is a preservation booster, but not an actual standalone preservative. It is usually included in addition to more reliable preservatives.

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It depends. Usually yes, you want correct pH before adding the ingredient, because some ingredients might be sensitive (for example Sodium Ascorbyl Phosphate). But some (Niacinamide) are that sensitive to pH, so it can be adjusted later.

I don’t know about Alpha Arbutin, but it is better to be safe - measure and adjust the pH before and after addition (because the ingredient itself can change it)

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If you need a formulation service you can get it in another topic here: https://chemistscorner.com/cosmeticsciencetalk/discussion/formulation-services-needed-get-help-here/

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Allantoin solubility is 0.5% top. You have 40% water, so 0.2% is top.

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We need to know the testing procedure and efficacy criteria to answer the question

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If you need a formulation service - go here: https://chemistscorner.com/cosmeticsciencetalk/discussion/formulation-services-needed-get-help-here/

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Are you actually a cosmetic chemist? Because Azelaic Acid is almost insoluble in water

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In strongly acid solution ascorbic acid decomposes to furfural and carbon dioxide (Herbert et al., 6; Lamden and Harris, ll)

Sodium metabisulfite decomposes in 150 °C of heat releasing toxic gasses when decomposed

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What about glass jars? They much easier to sterilize - just boil them and then rinse with ethanol.

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Perplexity doesn’t generate own answers, it summarizes google search with AI. You can do it with OpenAI’s ChatGpt too, just enable “Search” mode.

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Maybe licorice extract darkens over time?

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Ferulic Acid is show to stabilize ascorbic acid, not the derivatives.

Tocopherols are oil-soluble, so I don’t see how it should stabilize water-soluble active.

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Aha… Then I see why cosmetic grade is more expensive. Thnx!

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Sepimax Zen? According to their marketing materials it should tolerant to acids and high glycol content

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Indeed. Acidic pH is good for bacteria that causes cavities, so I would be surprised to find acidic toothpaste

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For us the difference between cosmetic grade and food typically comes down to micro spec- lower for cosmetics than it is for food

Lower micro spec for cosmetics grade means less microbes allowed or more microbes allowed? (sorry, not native English speaker)

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I agree that it is exactly what happened. 5% of Curcylic is 2% of Salicylic Acid. Since pKa is below 3%, SA drops pH very much and the solution is losing the viscosity.

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I heat the SA with propanediol 1:15 ratio and then I mixed it with water

Solubility of SA is affected not only by amount of solubilizer, but other additions too. When you add water you decrease the solubility. When you have pure propanediol - you have very high solubility. When you have water+propanediol mix your solubility of SA in it is different. There is a whole study on how to calculate solubility in a mix of solvents: https://pubmed.ncbi.nlm.nih.gov/16649546/

I wrote an article on reddit on how to formulate SA in DIY based on my experience, commercial products and studies. It also contains few formulas: https://www.reddit.com/r/DIYBeauty/comments/1d22zx8/formulation_guidelines_for_salicylic_acid_2_serum/

pubmed.ncbi.nlm.nih.gov

Solubility prediction of salicylic acid in water-ethanol-propylene glycol mixtures using the Jouyban-Acree model - PubMed

To show the applicability of a solution model, i.e. the Jouyban-Acree model, for predicting the solubility of a solute in ternary solvent systems based on model constants computed using solubility data of the solute in binary solvent systems, the solubility … Continue reading

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