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Remaking a formula…. Help
Having a hard time reproducing this sunscreen formulation from the previous person… not sure if it is O/W or W/O. Hoping to change out the sunscreens to ZnO. These are not percentages but in GRAMS….
gramsDeionized
Water (0.2 µm filtered)56.030 Carbopol Ultrez 20 0.140 Carbopol
Ultrez 100.140 dermopeel
PA-150.090 butylene
glycol1.880 stearic acid 1.880 cetyl alcohol 0.940 lipo gms 470 0.940 span 83 1.880 almond oil 4.690 avocado oil 2.820 jojoba oil 1.880 shea butter 1.410 pelemol
bip-pc0.940 3-sunscreens
-total19.700 vitamin E 0.140 amp 0.470 allianz
opt-c5g2.820 botanistat
pf-640.940 -
12 Replies
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These sunscreens are harder than people believe and it is a huge mistake to minimize the technical demands. Only the most experienced Formulators, with proper equipment and experience should make these products.
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Because I don’t know the 3 sunscreens nor the manufacturing procedure, I can only guess: Judging from the empoyed emulsifiers, this does look like an unstable w/o emulsion or alternatively an unstable polymer-stabilised o/w or w/o/w emulsion. I tend towards a w/o emulsion which only holds because of the high melting range of the oil phase and an inner gelled aqueous phase.Should you ditch the sunscreens for zinc oxide, remove pelemol
bip-pc and use an entirely different emulsifier and polyme blend (as you noticed yourself, they don’t hold and both will most likely crash when you use zinc oxide)
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100pct agree with @Microformulation.
You cannot expect to create a cosmetically elegant, stable, and effective zinc oxide sunscreen unless you are really an expert. Please understand that there are established brands struggle to do this well. -
Addition to my earlier post: I just realised that there’s AMP in higher amounts present. This indicates that at least some (too lazy to calculate) part of stearic acid is neutralised which makes the emulsion more likely to be o/w. I still don’t think that it will deal well with a switch to ZnO.
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Hello
Thank you for all the comments!!! Please excuse my new-ness on the topic.
I have very little experience working with sunscreens and have always recognize the seriousness of their formulations. The managers are demanding I work on this project and make it like what the last chemist did. They didn’t procedure just a list of raw materials and their quantities in GRAMS. I am trying to figure out what is going on with this formulation.
The 3 sunscreens that I am trying to switch out with ZnO or a combo of ZnO/TIO2 are octocrylene, ethylhexylsalicylate and octylmethoxycinnamate. The product has to work for pregnant women.
@Pharma
What would be a better emulsifier system? I must admit my resources are limited but I can order.
When you say polymer blend are you referring to all the oils?
“Addition to my earlier post: I just realized that there’s AMP in higher amounts present. This indicates that at least some (too lazy to calculate) part of stearic acid is neutralized which makes the emulsion more likely to be o/w.”If the stearic acid is neutralized how does that effect the system?
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so there is nothing wrong with using just grams and not percentages? I am trying to figure out what to do with this besides reformulating this mess. -
Using grams is fine as long as everything adds up to 100 g. In this case, grams equals % .Pregnancy safe? So you’re not going to work with nanonised oxides, are you?Okay, the old and simple oil-soluble sunscreens (BTW that blend is mostly absorbing UVB). In that case they fully count to the oil phase… anyway, I did some rough maths and ended up with max 1/4 stearic acid which could be neutralised, maybe less. Depends on final pH, product purity etc. That’s not a % which I would deem sufficient for proper emulsion stability, especially not in conjunction with all those w/o emulsifiers.How neutralised stearic acid affects the system? Well, it turns it into stearate soap or, in other words, an anionic emulsifier. This is something you should know if you’re working in cosmetic product development.Regarding your Q about a better emulsifier system: That’s like asking ‘What’s a better moon rocket than a firecracker?’ You’re going to have to work with a lot of oxides… good luck with that!No offence but I sincerely doubt that this job is a job you should do, not with your current know-how. Maybe your managers should switch jobs too…
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if this is for your work and you have a company email I’d suggest making a ULprospector account. there are some supplier made formulas there you could use as a better starting point- sometimes its better to start fresh than to keep patching holes. ultimately pharma makes a good point, you won’t be able to understand what changes you can make without some more foundational knowledge.
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this is for work. i have some industry experience not with sunscreens or the other hard stuff. Yes starting fresh was an idea of mine. I was just trying to match the texture so the sales rep doesn’t yell at me again.
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I am no expert in sunscreen or even basic formula, but I imagine matching the texture of 19.7% octocrylene, ethylhexylsalicylate and octylmethoxycinnamate with ZnO/TIO2 using the old formula as a starting point would be hard.
As a sale person - if the new texture is very similar to the old one but with a new or better claim, that can be good material for marketing too.
Good lck
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@Stanley If you want to use either ZnO or TiO2 in yor sunscreen, you might find helpful to use some esters (like C12-15 Alkyl Benzoate or Isopropyl myristate), in fairly high amounts. this would increase not only texture, but also increase spreadability and overall SPF.
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@ketchito
thank you kindly for the suggestion.
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