Question: Why should I mix sunscreens?
Answer: There are several plausible scenarios where mixing a sunscreen with another skin care product would yield a desirable outcome. The reasons can usually be placed under two broad categories: a cosmetic or formulary concern. A cosmetic concern would be if for example, you’d like the sunscreen to mattify more quickly or to provide some coverage. The reasons that fall under this category tend to stem from personal preference. A formulary concern would be if for example, you’d like more sun protection protection. The reasons that fall under this category tend to stem from necessity, which is dictated by science or personal experience.
Whatever the reason is, the combination of the two or more hypothetical products need to satisfy the following prerequisites in order of importance: provide adequate UVA- and UVB-protection, as well as adequate levels of antioxidant protection (if a separate product is not used).
Question: How do I mix sunscreens?
Answer: The requirements necessary for a good sunscreen are:
- Adequate UVA and UVB protection;
- Adequate antioxidant protection (if a separate product is not used); and is
- Aesthetically pleasing.
Before getting to the logistics, it’s important to note that it’s probably best to not mix sunscreens that contain organic UV filters, meaning the ones that contain ingredients like avobenzone, oxybenzone, or homosalate. This is because these ingredients are quite sensitive and can give largely fluctuating degrees of sun protection based on several factors such as: type of vehicular based used, interactions with other chemical sunscreens, interactions with metal oxides, and inherently variable concentration-to-efficacy ratios. It would be rather difficult for the average consumer that doesn’t have access to a chemical lab, to reliably create a new and dependable formulation. Therefore, this post will only discuss the mixing of physical sunscreens like zinc oxide and titanium dioxide.
Step 1: Make sure the two products you’re trying to mix are primarily mineral-based sunscreens.
Why do we do this? Like I said above, organic sunscreens are a bit more temperamental compared to their inorganic counterparts. But why not use another product that isn’t a sunscreen, such as an antioxidant-rich serum or a makeup primer? Here’s why. By mixing two sunscreens, the one with the lower sunscreen rating will guarantee a base level of sun protection at that rating. And since we’re using physical sunscreens, it’s easier to reliably calculate the level of sun protection.
Step 2: Mix “X” parts of sunscreen 1 (SUN1) with “Y” parts of sunscreen 2 (SUN2) (X:Y)
For example, mix (1:1), or (1:3). Whatever ratio you decide, keep in mind the THREE requirements that I enumerated above and the order of importance. Should you encounter a dilemma where you’re balancing the amount of sun protection against the how well it wears under foundation, I’d suggest finding that happy medium (not necessarily 1:1), that still satisfies the THREE requirements.
So how do you reliably calculate how much sun protection you’re getting from your personal concoction? Use the Sunscreen Simulator, one of the links displayed on the homepage, to calculate approximately how much sun protection you will be provided.
For those of you who are interested, I’ve created a very elementary algebraic system to use:
- A1 = Concentration of Sunscreen Type 1 in SUN1
- B1 = Concentration of Sunscreen Type 2 in SUN1
- A2 = Concentration of Sunscreen Type 1 in SUN2
- B2 = Concentration of Sunscreen Type 2 in SUN2
- X = Parts Present in A3
- Y = Parts Present in B3
- A3, B3 = Concentrations of Sunscreen Types 1, 2 in SUN3; these numbers are what you enter into the respective fields on the above-mentioned link
A3 = A1 x (X/(X + Y)) + A2 x (Y/(X +Y))
B3 = B1 x (X/(X + Y)) + B2 x (Y/(X +Y))
Let’s do an example just so everything is glass clear. (Get it? Haha!)
Here’s what we know:
- SUN1 contains 9% Titanium Dioxide and 5% Zinc Oxide.
- SUN2 contains 7% Titanium Dioxide and 2% Zinc Oxide.
- We’re going to mix 1 part of SUN1 with 2 parts of SUN2.
A3 = 9 x (1/(1 + 2)) + 7 x (2/(1 +2)) = 7 2/3 or ~7.667%
B3 = 5 x (1/(1 + 2)) + 2 x (2/(1 +2)) = 3%
So, we’d enter 7.667 into the titanium dioxide field, and 3 into the zinc oxide field.
Now, if you’re actually doing this with me, you’ll see that there’s separate fields for the oil and water phases of each ingredient. Inorganic UV filters tend to always be coated, relegating them to the oil phase. There are exceptions, but that’s the general case.
For our scenario today, we’ll be using the oil phase to calculate the amount of sun protection you would be getting.
- Protection of SUN3 in the oil phase AND using the Real-Life rather than Clinical Calculations: SPF = 15.9, UVA-PF = 6.1.
Note that the amount applied should be about 2.0 mg/cm^2, the international standard.
I hope that helped everyone and if you guys have any questions, as always, I’m here to answer them!
The Triple Helixian 
Hello,
Thanks for the post! I was just wondering about applying makeup over sunscreen. I use La Roche Posay anthelios (Dry touch gel) which contains mexoryl and avobenzone and I have recently read that avobenzone is degraded by titanium dioxide. Does this mean that if I wear my Bobbi brown liquid skin foundation (1% Titanium dioxide) I am degrading my sunscreen.?
Thanks,
Emma
Posted by Emma | August 18, 2014, 12:15 pmNo you don’t have to worry about when layering items, since the amount of interaction between the avobenzone and titanium dioxide is negligible.
Posted by John | September 17, 2014, 4:05 pmI’m only twenty, but a lifetime of California sunshine is starting to take its toll.
For years, I used to run track. In high school, I ended up in the marching band. Oftentimes, I’d neglect to put on sunscreen. In moments when I would apply sunscreen, I now know that I drastically under-applied. I’ve lucky in that I tan easily and rarely burn, but I think that might have hidden the problems that are now evident. I have hyperpigmentation, wrinkles… a slew of problems that I know has been expedited by all that UV exposure.
I’m working to change that. Your site has been invaluable in learning what ingredients to look for, how much to apply, and more.
Here’s the thing. As a college student, I’m on a strict budget and I’ve been looking for an affordable sunscreen that meets the criteria that I’m looking for (a mineral sunscreen that is fragrance-free and noncomedogenic).
On another site, I’ve read testimonials that baby diaper rash cream containing zinc oxide could function as a sunscreen .I’ve found four products that I think hold potential:
1. Aveeno: http://bit.ly/SP4tpi
Ingredients: (Zinc Oxide: 13%) Avena Sativa (Oat) Kernel Extract, Beeswax (Apis Mellifera), Benzoic Acid, Dimethicone, Epilobium Angustifolium (Canadian Willowherb) Extract, Glycerin, Methylparaben, Microcrystalline Wax, Mineral Oil (Paraffinum Liquidum), Oenothera Biennis (Evening Primrose) Seed Extract, Potassium Hydroxide, Propylparaben, Sorbitan Sesquioleate, Synthetic Beeswax, Water
Price: 3.7 oz for $5.99
2. Susan Brown: http://amzn.to/1n7bQ3C
Ingredients: (Zinc Oxide: 12.5%) Water (aqua purificata) purified,Zinc oxide,Jojoba esters ,Ethyl macadamiate,Ethylhexyl palmitate,Glycerin,Polyglyceryl-4 -isostearate ,Extracts of anthemis nobilis (chamomile),Avena sativa (oat kernel) ,Calendula officinalis (marigold) ,Theobroma cacao (cocoa) butter,Butyrospermum parkii (shea) butter,Moringa oleifera butter,Benzyl alcohol ,Methylisothiazolinone,Tocopheryl (vitamin E) acetate,Bisabolol,
Price: 3 oz. for $8.99
3. Triple Paste: http://amzn.to/1lu3Z4S
Ingredients: (Zinc Oxide: 12.8%) White Petrolatum, Cornstarch, Anhydrous Lanolin, Stearyl Alcohol, Beeswax (Apis Mellifera), Bisabolol (L-Alpha), Cholesterol, Water, Glycerine, Oat Kernel Extract (Avena Sativa), Polysorbate 80
Price: 2 oz. for $6.79
This means I would be paying roughly between $2-3 per oz, rather than the $5/oz for a mineral sunscreen by Blue Lizard or Badger.
4. I’ve also found a product that is simply zinc ointment, a 20% zinc oxide suspension in white petroleum and mineral oil. From what I’ve read, I don’t believe this would be comedogenic.This would only cost $10.45 for 1 lb. (http://amzn.to/1lA4YyP)
I would use these “sunscreens” as a primer, and then cover the result with a loose mineral foundation powder that is predominantly mica and titanium dioxide.
I know it’s unconventional, but if the ingredients in these alternatives are kosher, I’d be down to try it out.
What do you think? Would this work?
Posted by Danielle | June 16, 2014, 8:17 pmHi Danielle!
I’m so glad that you found this website! I do hope that I’m not responding too late.
Despite your budget limitations, I’d actually recommend none of these products primarily because they have not been tested by the FDA as a sunscreen, hence no SPF rating. Depending on how zinc oxide is used in a formula, the SPF rating could fluctuate a lot. Furthermore, I don’t think you’d like the texture of the diaper creams; you’ll probably end up hating the sunscreens.
I would however recommend the Cerave Body Lotion SPF 30, which is around $4 per oz. It provides significantly more UVB and UVA protection, comparatively; and the price is only slightly higher. As a high-mineral content sunscreen, you will notice a drying and whitening effect when you apply this at the recommended ~1/4 teaspoon amount.
But anyways, let me know how things work out!
Posted by John | July 11, 2014, 10:24 pmHi John, how are you?
Beetwen a SPF30 20% Zinc Oxide Sunscreen and a SPF30 with Tinosorb M+S, Tio2 and Octinoxate, what would you use?
What do you think about reapply a Tinosorb sunscreens? (since M is an hibrid – physical and chemical- sunscreen).
Consider that Phloretin CF would be applied under the sunscreen.
And do you know the name of the sunscreen that is very similar to Elta MD Uv Clear, without niacinamide?
Posted by Mat | October 1, 2013, 8:46 pmIt’s hard to know which product provides more protection since the concentration of UV filters is not available for the second product. I’d be more able to give a recommendation if you had the full ingredient list. Oh, and the product that’s similar to the UV Clear is from the PCA Skin line. I believe it’s the SPF 45 one.
Posted by John | April 21, 2014, 3:50 pmhey john! just got myself a sample of bioderma sunscreen. While i cannot say for sure whether it is drying out my skin or not ( not used enough), reading the ingredients i did read octocrylene was high on the list. Then looking further into this , i read that this octocrylene is a photosensitizer , and induces free radicals when exposed to sunlight.Whats ur opinion?Also what about the claim that melasma is further triggered by chemical sunscreens, as melasma reacts not only to sunlight but also heat? All in all can i use this bioderma without having to worry about my melasma and free radicals?
Posted by charu alwani | July 6, 2013, 5:41 amIn essence, no you don’t have to worry. Please read this post for more information: http://www.futurederm.com/2012/09/03/are-inorganic-sunscreens-better-than-organic-ones-part-iii-toxicity/
As long as you’re applying enough sunscreen that has high photostability, and reapplying if and when necessary, you will be fine. And you can always go the inorganic sunscreen route.
Posted by John | July 7, 2013, 7:14 pmThanks John!:-)
Posted by charu alwani | July 8, 2013, 5:41 pmWelcome! Good questions.
Posted by John | July 8, 2013, 6:41 pmDear John,
What about tinosorb m and tinosorb s? from wht i know these are chemical filters as well? However i never feel chemical uv filters give me enough protection(i am prone to sun induced pigmentation), so I was thinking applying this with my elta md uv clear spf 46 or any other high % zinc oxide sunscreen. In essence first applying bioderma , then elta md. what do you think ? would this work?however even if i do this , there is still no titanium dixode in my sunscreen , which i believe reading your article on organic vs. inorganic sunscreens is also important . please suggest something? also i am worried about the alcohol in bioderma max fluid as i fell any alcohol or fragrance pigments my skin even more when in sun. what do you think?
lastly i have also heard that antioxidants such as mulberry, vitamin c , grape seed extract,citric acid are phototoxic , hence increasing photosensitivity of skin when exposed to sunlight. what do you think? please let me know 🙂
Posted by chaaru alwani | June 30, 2013, 7:12 amHi Chaaru,
You’ve asked a lot of questions that aren’t really related to one another. But I’ll try and answer them as succinctly and clearly as I can.
Does that make sense?
Posted by John | June 30, 2013, 6:44 pmHey john,
Thanks for the amazingly detailed +organized (contrary 2 mine ..lol)answer! So i think for now will stick to bioderma for now.Just One question: regarding a product with coverage containing inorganic UV Fillers… I was thinking dermalogica agesmart Skin Perfect ,however it is to pricey for me + scared the capryl triglyceride will break my acne Prone combo Skin out.whts Ur opinion,wht wud u suggest otherwise providing similar % of ZnO and TiO?
Lastly what do you think of la Roche Posay as Sun protection? I was using la Roche Posay extreme Fluid SPF 50 for a Long time, only to find it drying Out my Skin and Increasing the patchiness and pigmentation Even more,which i uptil now had Thought was because of the alcohol whch was making my Skin dry and sunsensitive, hence have avoided any chemical sunscreens from then on.but now that u say alcohol is not the culprit y do u think lrp did Not work?
PS: Sorry for the doubleposting…..unsurity and confusion makes me restate things!Skin care can be such a complicated thing sometimes , especially with my supersensitive skin i read each and every Ingredient on the label trying to avoid most of them just in case they cause irritation my skin,however I do realize how annoying this can get for the other person and will try not to repeat the same again + vl try to be more structured and organizd in my next post…hehe!
Posted by Charu Alwani | July 1, 2013, 2:24 pmHaha you’re welcome! But I wish I had MORE time to be even MORE detailed.
But yeah, the SkinPerfect is a good sunscreen too, though still not as good as the BioDerma in terms of absolute initial sun protection. And that coconut fatty acid, and several other ingredients present in relatively high concentrations, can certainly contribute to blocked pores. So you may want to look elsewhere or at least get a sample. Besides, the Dermalogica product is quite expensive at ~$64.00/oz. And since you have to apply so much sunscreen in order to get the labeled amount of protection, it’s just not worth it.
As for the LRP sunscreen, keep in mind that concentration, not just identity is also important. The alcohol content is probably ~15%, which is significantly higher than that present in the other product. Not to mention that several of the main vehicular ingredients of the other product are already drying themselves; they compound the effects of the alcohol content. Hence, the super drying you experienced with the LRP sunscreen.
Does that make sense?
And as I said in my response to your other comment earlier today: Relax! I’m always going to be here, so just ask questions on this blog and I’ll eventually get around to answering them.
Posted by John | July 2, 2013, 9:21 pmhey! that makes super sense! things seem much clearer all thanks to you! and vl sure ask u any more questions i have and try 2 relax…hehe! THANKS:-)
Posted by charu alwani | July 3, 2013, 5:34 amYay! Good to hear.
Posted by John | July 3, 2013, 7:12 amhey just 1 more question how do you know the percentages/concentrations of ingredients in lrp and bioderma sunscreens,as european sunscreens dont list them??where can i find them out??
Posted by charu alwani | July 3, 2013, 7:35 amHaha are you sure it’s just one more question…? Lol!
Anyways, I don’t actually “know” for sure. They’re just accurate guesses based off of several observations and facts. For example:
From there, I can estimate how much of an ingredient, for example alcohol, is present, give or take.
So it’s not really an exact science; it’s more of a confident guess. Take that as you’d like.
Posted by John | July 3, 2013, 8:52 amive not opened the bioderma and vichy one yet, but from my haul that day, the vichy one seemed to be the most “alcoholic” (i left the boxes in my hometown but if im not wrong. alcohol is listed 3rd in the vichy uv pro secure). would you consider the alcohol content in the LRP Anthelios XL Extreme Body Fluid problematic? it’s 5th in the ingredient list after water, dicaprylyl carbonate, octocrylene, and cyclohexasiloxane. isononyl isononanoate follows after alcohol denat. im assuming that the alcohol shouldnt be problematic as it is probably thinning down the emolients right? i personally do not feel that it is drying, at least not like certain shiseido ones, but this does set to a tacky (almost moist) film that is quite water resistant. but after three weeks of continuous usage, i realized dry patches on my cheeks though.
Posted by nelson | August 2, 2013, 1:39 pmWell, you really just have to figure it out through trial and error. Since it’s listed after octocrylene, whose max allowable concentration is 10%, it is present at less than that amount. So it shouldn’t be too much.
Have you experienced any other side effects since you posted this comment?
Posted by John | August 12, 2013, 8:22 amooops! i myself have not been following up on your blog because i know of the stalemates you are experiencing! anyway, the flaky cheeks is no longer prevalent as i moisturized my cheeks with olay regenerist regenerating serum underneath during the day that time. but even so, right now, i am able to apply only the LRP (with nothing underneath) and experience no dryness. oh well skin fluctuations =)
Posted by nelson | September 2, 2013, 4:54 amWell, that’s great to hear. At least you’ve figured what works, and doesn’t work for you.
Posted by John | September 3, 2013, 5:02 pmwhen i mix my sunscreen with 20% zinc oxide only, (SPF 30) together with an equal amount of another sunscreen with 2% zinc oxide only (SPF 8),.does that equal 32% zinc oxide with an SPF of 38 as I’ve been told by a reputable sunscreen manufacturer, as well as, by my aestheciian and per your answer to Theresa above “since you’re using zinc oxide as the sole mineral sunscreen..” Your article was helpful with calculating sunscreen mixes for UVA and UVB components but perhaps the above calculations are unneeded, adding together only the zinc oxide component as I had been told.
Posted by k.miller | April 29, 2013, 4:12 amHm, I’m not quite sure what you’re trying to say here. Can you elaborate a bit further? Thanks!
Posted by John | April 29, 2013, 5:55 pmi would like to mix (non nano) zinc oxide with only water for a sunscreen as i already have oily skin. is this possible? It would be for my own use and I could refrigerate it if necessary.
i read somewhere that antioxidants cause more free radical behaviour with sunscreens rather than enhance. Do you agree with this or is it only citric antioxidants?
I hope you can answer me. Rather than make my own physical blockout, are any of these products physical blockouts and if so would you recommend any of them or recommend one for me please.
Avobenzone (Parsol 1789) can degrade quickly
neutrogena Healthy Skin Compact Makeup SPF 55
Jane Iredale offers PurePressed Base SPF 20,
Avene Water Resistant SPF
johnson & Johnson’s Helioplex® Technology
Posted by emmy | March 16, 2013, 4:42 amNo, I wouldn’t recommend mixing just plain water with zinc oxide as a DIY sunscreen since that’d be ineffective. Once the water dries and evaporates, you’ll be left with just clumpy powder on your face, as the zinc oxide will recrystallize in the absence of water. There are DIY sunscreen recipes out there, but since there’s no way to test efficacy, I wouldn’t recommend making your own sunscreen, unless you really know what you’re doing and have the necessary equipment.
As for the antioxidant issue, that is not true. Where did you hear that from?
Finally, you never have worry about whether or not I will answer a reader’s comment. I read and respond to every genuine comment. 🙂 Also, despite the fact that avobenzone does degrade quickly, there are still several organic sunscreens out there that are quite good. You have to decide whether you prefer inorganic or organic sunscreens. See my series on the differences between the two here: https://thetriplehelixian.com/category/pages-in-detail/sun-protection-in-detail/inorganic-sunscreens-vs-organic-sunscreens/
Now, the Neutrogena product that you mentioned, as well as all sunscreens with Helioplex are organic sunscreens. The Jane Iredale Powder Foundation is a mineral “sunscreen.” But keep in mind that because it’s a powder, you’ll never apply enough to achieve the adequate levels of photoprotection, so you can’t really consider it a sunscreen, which needs to be a liquid. But you can definitely layer this over your dedicated liquid sunscreen. Finally, I’m not sure which Avene sunscreen you’re referring to, so I can’t give you my thoughts on it.
Does that all make sense?
Posted by John | March 16, 2013, 10:36 amyou are the best, John! Thank you!!!
Posted by madeline | November 8, 2012, 8:27 pmYou’re super welcome!!
Posted by John | November 8, 2012, 11:04 pmI am still trying to process this…
🙂
Posted by BooBooNinja | June 22, 2012, 12:22 pmTake your time!
Posted by John | June 23, 2012, 2:49 pmHi John!
Could you please clarify a couple of things about this article for me? In step 1, are you saying that it isn’t okay to mix a makeup primer or serum with your sunscreen? Also, I’m using a moisturizer with sunscreen (zinc oxide and octinoxate), but it’s only an spf of 15, so I’ve been using a separate sunscreen over top of it (it’s only got chemical sunscreens). But is this preventing the sunscreen from working since it’s mixing with my moisturizer with spf?
Posted by Theresa | April 18, 2012, 1:26 pmHi Theresa,
Keep in mind that I define a sunscreen as anything that contains active sunscreen ingredients. It doesn’t matter what it’s labeled as. For example I consider the Hourglass Mineral Veil Primer as a sunscreen because it contains both the titanium dioxide and zinc oxide mineral active sunscreens. So what I mean in Step 1 is to make sure the two products that you’re mixing both contains sunscreen actives for both UVA and UVB rays. And they should also be mineral-based sunscreens.
Therefore, since you’re using just zinc oxide as the sole mineral sunscreen, this article wouldn’t really apply for the MIXING of sunscreens. Just because chemical sunscreen effectiveness is much more susceptible to things like vehicular base, interactions with other chemical sunscreens, and the other ingredients present such as iron oxides.
However, what you’re doing is also acceptable, except that you should flip the order of application. Because chemical sunscreens need to come in contact with your skin in order to work, you should apply the separate chemical sunscreen first, wait for it to dry, then apply the sunscreen that contains both zinc oxide and oxtinoxate.
I hope that made sense, and if you have additional questions, of course I’ll be here! Thanks for commenting!
Posted by John | April 18, 2012, 8:39 pmHi John! I had one more question. I recently started using the Estee Lauder Perfectionist serum because I read that sunscreens work better when they mix with antioxidants. Should I use this over top of my sunscreen since it’s a chemical sunscreen and as you said it’s better if it comes into contact with my skin? Or would it be sufficient if I apply the serum and wait for a bit for it to sink in before I apply the sunscreen? Would the silicones in the serum prevent the sunscreen from working properly if worn over top? Thanks a lot for answering my previous question! (Also, your blog is awesome, please keep the posts coming!!)
Posted by Theresa | April 28, 2012, 3:41 pmHey Theresa!
Antioxidants do enhance the UV protection of sunscreens, some more than others of course. Fortunately the Perfectionist contains a high amount of grape seed extract, which is is great! Of course you can check my product review of that serum for more information.
Anyways, while it is true that the closer a chemical sunscreen is to your skin the better, the cons outweigh the pros if you’re going to apply something over it. Chemical sunscreens are very sensitive to vehicular changes and anything you apply on top could inhibit its ability to function. So I’d definitely recommend applying the serum first and then wait a few minutes. Then go ahead and apply your chemical sunscreen. As with all chemical sunscreens, you’ll have to wait at least 30 minutes before any sun exposure. To avoid all this and other potential issues, go with a mineral-based physical sunscreen instead!
Thank you for your continued support and contribution. And never hesitate to ask more questions! I love them. 🙂
Posted by John | April 29, 2012, 8:51 pm