Can I mix my own sunscreen? Episode 132

How do I find a sunscreen that doesn’t cause acne?


Allison asks…What’s the difference between a sunscreen and a sunblock? Also, what ingredients should I look for in a product that will not contribute to acne? And, when’s the best time to apply sunscreen in my morning skin care routine?

Sunscreens use UV absorbers to protect your skin while sunblocks use minerals like zinc and titanium compounds to scatter the sunlight and prevent it from reaching your skin. (Actually, the regulations in the US have changed recently and companies are not allowed to call their products sunblocks anymore.)
Both types of sun protection products are classified as drugs by the FDA which has determined that they are safe and effective. That doesn’t mean, however, that they’re without controversy. Some people find the so called “chemical” sunscreens to be irritating and there is concern that some of these ingredients may be endocrine disruptors. On the other hand, some of the physical sunscreens (which have long thought to be very inert) may interact with sunlight in such a way to damage skin.

Should you worry about which type of sunscreen ingredient to use? For now, I’d continue to go with the FDA’s recommendation on what’s safe and effective and not pay too much attention to all the rumors you might hear about these ingredients.

When it comes to acne, it’s impossible to tell you for sure which sunscreen ingredients to look for and which ones to avoid. I say that for a couple of reasons. First, in addition to the sun protection ingredient there are many other ingredients used in the formula. Sometimes a carrier oil a product can make another ingredient more likely to cause acne. (A classic example is red dye. As a powder it doesn’t cause acne but when combined with certain oils it does.

You might have luck looking for a sunscreen that’s labeled “noncomedogenic.” But, that brings me to the second reason which is that comedogencity testing is not an exact science. That kind of test has historically been done on rabbit ears and it just doesn’t extrapolate very well to people.
Finally, in terms of when to apply sunscreen in your morning routine – typically sunscreens should be applied first so they can soak into the skin and form a protective film. You should do this about 30 minutes before being exposed to strong sunlight.

Can I mix my own sunscreen?

Mindy asks…So the sunscreens in moisturizers that I use has only small amount of ZO, 3%. I usually use it first thing in the morning. I would like to put some sunscreen on before driving home in the afternoon.

I don’t want to put on moisturizer over my makeup, and I don’t like the off the shelve sprays because they feel oily. I was thinking if I put 5% ZO and 5% TiO each (or 10% if 5% is not enough) in witchhazel as a spray, would it work as a sunscreen? I use Thayers Witch Hazel Alcohol-Free Rose w/Aloe Vera. I know it would not be water proof. I just need something to top off my sunscreen in the afternoon.

I hate to tell you this Mindy, but this NOT a good idea for several reasons. First, the physical sunscreens you asked about are not soluble water or even water-alcohol solutions. That means whatever you put in which just settle to the bottom of the bottle.

Now, I know what you’re thinking…can I just shake it up really good before I spray it? NO! These materials, especially TiO2, tend to aggregate if they’re not properly dispersed. That means the little particles come together to form larger particles. Not only would this make it hard to spray but it reduces coverage on your skin and impacts the product’s efficacy.

And don’t even THINK about trying to mix them into a different product form like a cream or lotion. You can make a stable dispersion in a cream but to get them to mix properly you have to sheer these things like a mother f*c&@r! Finally, even if you could get the particle size small enough, I don’t think these materials are safe to inhale. Not used in spray sunscreens to my knowledge.

The bottom line is don’t screw around with making your own sunscreen.


Are mineral sunscreens more stable?

Eva asks…Do I really have to reapply physical sunblock (zinc based) every 2 hours? (Assuming my skin don’t perspire or sunscreen doesn’t get physically rubbed off.) Also, for zinc based sunblock, does the 3 year expiration date really apply?

First, the so called “chemical sunscreens” or the UV absorbers (as opposed to the UV blockers) actually get used up over time. It works like this: a molecule of sunscreen absorbs a photon of UV light and then remits the light at a different frequency that doesn’t damage your skin. But every time it goes through this “absorption/re-emission” cycle, it fatigues the molecule a little bit and eventually it will break down and stop working. That means you need to reapply more.

That’s NOT the case with the mineral sunscreens because they reflect the UV light instead of absorbing it. So it is reasonable to ask if physical sunscreens can be applied less frequently.
But the problem is these mineral sunblocks WILL be physically removed from your skin – either by sweating or from rubbing against your clothes or from jumping in the pool. You CAN’T make the assumption that you don’t perspire or that it won’t get rubbed off because it will. Even just touching your face unconsciously a few times will remove some of the lotion. So if you want to make sure your skin is protected, yes, you have to reapply.

You also asked if expiration dates apply to zinc based sunscreens and the answer is yes because the emulsion in which the zinc/Tio2 is suspended may not be stable for that long especially if it’s left in the sun, hot trunk of a car, etc. The particles of the physical sunscreen can agglomerate and they wouldn’t be as effective.

Beauty Science News of the Week

Color changes at Kraft


Here’s an interesting announcement by the Kraft company about their mac and cheese product. How does this relate to beauty products? Well, I’ll get to that in a moment.

Kraft just announced that it reformulated it’s classic Mac and Cheese product by removing artificial preservatives, flavors and dyes from it’s products.

To do this they replaced standard food colorings with spices like paprika, annatto and turmeric. For preservation they probably rely on a low level of water and high level of salt. In fact an entire box of the stuff contains 72% of the recommended salt intake.

The interesting part of this story is that they made the change back in December of 2015 and they are just telling people about it now. They’ve sold 50 million boxes and apparently no body noticed the changes.

This kind of thing actually happens a lot in consumer goods industries like food and cosmetics. In fact, your favorite products are being changed right under your noses pretty frequently.

Now, Kraft claims that they made the changes because of requests from parents. I’m a bit more cynical and I think this was a marketing ploy to trick consumers into believing that Mac n Cheese will now be more healthy for people. I should say that there is no evidence the changes they made (removing artificial dyes and flavors) made the product more healthy. Indeed with a 72% of the level of recommend salt intake it still doesn’t seem like much of a health food.

So, marketing reasons is one reason a formula might be changed.

Another big reason is cost savings. We spent a lot of time coming up with formulas that would perform the same but be less expensive. For hair products maybe you change the fragrance level or the detergent level or make other minor tweaks. Consumers are surprisingly bad at noticing differences.

Another reason to change formulas is because of regulatory reasons…

Finally, when a big company buys a small company they often have to change formulas to get economies of scale.

When companies do change formulas they go through consumer testing to do their best to ensure that people don’t notice a difference. This is what Kraft no doubt did before launching their new reformulated macaroni and cheese. Mostly, people didn’t notice. And since the product is eaten mostly by children it doesn’t surprise me much. Even if a kid noticed a subtle difference I doubt they would say anything to their parents.

One thing about these formula changes is that while they aren’t typically noticeable by a population, individuals might notice more. So, if you have a product that you’ve been using forever and it seems to not be working the same, there’s a pretty good chance that the formula has been changed.

Writing about beauty science may enslave rather than empower


You may be familiar with the website “Realize Beauty” which is written by Amanda Foxon-Hill who’s a cosmetic chemist in Australia. She recently published an article that really resonated with me and I wanted to get your thoughts and also see what our listeners think about it. I’ll put a link in the show notes so you can read the entire thing, but I’ll quickly summarize it here. The gist of the article is that she’s asking herself if writing about beauty science actually empowers people.

After some reflection, she says that no, it doesn’t and that that in some cases “the scientific discipline that I am a part of has contributed to a dumbing down of the very thing I was trying to promote.” She explains by saying that “Anyone can blog about cosmetic chemistry and these days anyone does.” She says at first, bloggers who wrote about beauty science were industry experts who wanted to help people better understand how products work and so forth. (That certainly describes us!) But now she says that “people with very little or no experience of how the industry works or what procedures, guidelines or laws are in place in the global marketplace are now happily sharing their pearls of wisdom out onto the general public and passing it off as gospel.”

As that has happened, she feels that people are becoming more paralysed by all this information – they may “FEEL they’re getting the right answers but in reality they “are often completely lost.” In addition, she says when people realize they don’t know whether or not they can trust the answers to these endless questions about what’s true and what really works, they become frustrated and even angry. There’s so much conflicting advice, which on the surface seems reasonable, that people don’t know where to turn. So, it’s gotten to the point where she’s believes that writing about beauty science has the “POTENTIAL” to empower people but sometimes it just ends up enslaving them.

What do you think about that? I say look for real credentials!

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