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critique my formula: hydrating serum for acne prone, sensitive skin.
One ingredient I know I should be adding is a chelating agent.
Please tell me your thoughts on this hydrating formula. Mind you, my facial skin is sensitive to oils/silicones/fatty acids/petroleum. This is why my formula is free of those ingredients.
My goal for this serum is intense moisture, hydration, and skin-soothing. Barrier repair is another word I’d use for the goal of this serum.
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8 Replies
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Just my personal opinion, i’d recommend looking at consolidated percentages of humectants and individual humectants that are in the formulation.
The Natrasmooth contains Tremella, Betaine & Glycerin. If you are using liquid extracts, then the Licorice and Green Tea would likely have Glycerin in them as well, so depending on how much Glycerin you need, you might not need to add additional Glycerin as an individual ingredient since it would be tacky.
Depending on how well the Tremella & Hyaluronic Acid thickens, you might not need to add 1% Tara Gum as well, a lower percentage can be added to thicken slightly more if that is what you need.
You will need to make sure that the Optiphen is fully solubilized if that is your concern.
Also it depends on how well the Urea performs on your skin. It can hydrate but it can also add some tackiness and act as an exfoliator. Allantoin can also act as a mild exfoliator.
The percentage of Propylene Glycol is relatively high, you can consider lowering that based on how the skin feel goes.
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Please have a look to Urea; because of your water based formula it needs to be buffered to keep the ph stable. You can try a buffering system with sodium lactate and lactic acid. Sodium lactate is also a effective humectant which will show synergetic effects with glycerin.Betaine is good in combination with glycerin because of reduce the tackiness of it. But have a look to the total amount of glycerin - like Jemolian recommends.For barriere repair I will recommend an other kind of ingredients or an other product type. You may find effective barrier regulation with linolic acid (in natural oils, some are more oxidative stable like others) combined with phytosterols and hydrogenated phosphatidylcholine. It’s a little bit tricky to do this with acne pronouned skin - try to begin with a very low percentage dosage. You can formulate a hydro dispersion gel with low parts of lipids.
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High amount of humectants will make your skin drier if you don’t have occlusive.
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Heike said:Please have a look to Urea; because of your water based formula it needs to be buffered to keep the ph stable. You can try a buffering system with sodium lactate and lactic acid. Sodium lactate is also a effective humectant which will show synergetic effects with glycerin.Betaine is good in combination with glycerin because of reduce the tackiness of it. But have a look to the total amount of glycerin - like Jemolian recommends.For barriere repair I will recommend an other kind of ingredients or an other product type. You may find effective barrier regulation with linolic acid (in natural oils, some are more oxidative stable like others) combined with phytosterols and hydrogenated phosphatidylcholine. It’s a little bit tricky to do this with acne pronouned skin - try to begin with a very low percentage dosage. You can formulate a hydro dispersion gel with low parts of lipids.Sorry for the off-topic. Welcome to the forum miss Heike! You are a legend and truly inspirational person. I’ve learned a lot from Olionatura and the forum to the site. Despite of the fact that you are a natural cosmetics formulator, your opinion has been always objective.I really appreciate that! I think your presence here would be very positive, especially for the newest formulators. Greetings from Bulgaria.Alexander
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jemolian said:Just my personal opinion, i’d recommend looking at consolidated percentages of humectants and individual humectants that are in the formulation.
The Natrasmooth contains Tremella, Betaine & Glycerin. If you are using liquid extracts, then the Licorice and Green Tea would likely have Glycerin in them as well, so depending on how much Glycerin you need, you might not need to add additional Glycerin as an individual ingredient since it would be tacky.
Depending on how well the Tremella & Hyaluronic Acid thickens, you might not need to add 1% Tara Gum as well, a lower percentage can be added to thicken slightly more if that is what you need.
You will need to make sure that the Optiphen is fully solubilized if that is your concern.
Also it depends on how well the Urea performs on your skin. It can hydrate but it can also add some tackiness and act as an exfoliator. Allantoin can also act as a mild exfoliator.
The percentage of Propylene Glycol is relatively high, you can consider lowering that based on how the skin feel goes.
Thanks for your thorough comment.
It didn’t cross my mind about the liquid extracts containing the glycerin already. This is a great point.
You’re right, I think it is more thick than I would like. I used the tara gum to thicken but also primarily to provide a moisturizing, film forming effect. At least that is what MakingCosmetics says tara gum is capable of (this was the description for their liquid form that contains both regular and hydrolyzed tara gum).
I will either reduce the HA or reduce the tara gum next time. Leaning towards reducing the HA because the tara gum might have better moisture retaining properties.With the optiphen, all I do is add it at the end or in with the water phase (I have the glycerin, HA and propylene glycol in a separate cup so that I can make a slurry with the HA powder. I call this my ‘glycol phase’. I then add this glycol phase to the rest of the ingredients (the water phase) at the end. Hopefully that is enough to make solubilize the optiphen.
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Heike said:Please have a look to Urea; because of your water based formula it needs to be buffered to keep the ph stable. You can try a buffering system with sodium lactate and lactic acid. Sodium lactate is also a effective humectant which will show synergetic effects with glycerin.Betaine is good in combination with glycerin because of reduce the tackiness of it. But have a look to the total amount of glycerin - like Jemolian recommends.For barriere repair I will recommend an other kind of ingredients or an other product type. You may find effective barrier regulation with linolic acid (in natural oils, some are more oxidative stable like others) combined with phytosterols and hydrogenated phosphatidylcholine. It’s a little bit tricky to do this with acne pronouned skin - try to begin with a very low percentage dosage. You can formulate a hydro dispersion gel with low parts of lipids.
thanks for commenting Heike. I value all your points.
In regards to the topic of buffering and keeping the pH stable, I am a little confused (probs bc I’m still pretty much a novice). Are you saying I should try to keep the pH around the same level of the skin (5.5ish)? What pH ought my formula be at to be considered ‘stable’? I know that the preservative is pH dependent. I do follow up this serum with a vitamin C serum, so I guess making this formula more on the acidic side is preferable for various reasons.
In my manual by Zachariah Kovac, he says ” if the formula is too basic, add an acidifying agent
typically, citric acid @ 50%”…. At what percent should I keep a sodium lactate buffering solution? Do I add in a preservative and keep it in the fridge? -
ETcellphone, I’m sorry to let you wait.Urea inclines to hydrolysis when it is incorporated in a water solution. In this process the pH value increase, and this is a critical point for some preservatives. Some formulators prefer a combination of lactic acid with its salt sodium lactate. That will slow down the increase of the pH value.
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Heike said:ETcellphone, I’m sorry to let you wait.Urea inclines to hydrolysis when it is incorporated in a water solution. In this process the pH value increase, and this is a critical point for some preservatives. Some formulators prefer a combination of lactic acid with its salt sodium lactate. That will slow down the increase of the pH value.
thank you so much Heike, I appreciate your information
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