Sunscreen: Chemical vs Physical & What’s the Difference?

Daily sunscreen application is one of the most important things you can do for not aging your skin. You are preventing any future damage of wrinkles, discoloration and brown spots. The damage from past non sunscreen use won’t show up on your face for years, so you may think it’s not affecting your skin now, but in ten years all those issues will pop up in your face. We all know it helps prevent skin cancer and sunburns, but preventing oxidative stress and free radical damage is also a benefit. The formulas are so much better than they used to be and it only takes seconds to apply it everyday so there’s no excuse not to use it. Don’t forget around your eyes. And no not going outside doesn’t mean you get to skip it, UV light comes in through the windows as well and ages your skin everyday. Wear it, everyday.
This last summer I had some things happen that made me search for a new sunscreen and change from my regular La Roche-Posay Anthelios 60 Ultra Light Sunscreen Fluid that I had been using for two years. My dad had been diagnosed with lymphoma in June and I started going through ingredients looking at them on a different level than I ever have before. I realized the sunscreen I had been using for years was a chemical sun block and that Oxybenzone was one of the major ingredients. So I’ll talk about chemical blocks first and why I now hate Oxybenzone.
Chemical sunscreens work by binding to the skin and absorbing the UVA/UVB rays. Certain types of chemical sunscreens work well for UVA others for UVB, so they usually combine them to make the outcome most effective. Most people like chemical blocks for their usually thinner texture and don’t make your face have a white cast. You may not be aware that chemical blocks need to activate with your skin to be effective and that’s why you need to put it on 30 minutes before you go into sunlight. 
Technically chemical blocks really only work properly if you apply them first below your moisturizer. From what I have read, cleanse, tone, then apply your vitamin C serum, other serums, then your chemical block. I let this sink in for about 5 minutes and do other stuff. Then you can add your moisturizer over without pilling. If you add layers over the sunscreen too soon it tends to pill. Chemical blocks tend to last longer as far as being more sweat proof, but you still need to re apply every 2 hours because the chemicals absorb the UVA/UVB rays and then breakdown, making them ineffective to protect you past 2 hours well. There’s a lot of debate about the order to apply sunscreen in relation to other products. You know the thinnest goes on first like serums, then thicker products like moisturizer. Chemical blocks need to be as close as possible to your clean skin to activate and work in the FDA approved manner. So part of it becomes personal choice. 
The EWG(see my link on home page) lists sunscreen ingredients based on their safety. Oxybenzone is a popular chemical block but may have hormone like effects once absorbed. It has the lowest safety rating by the EWG of all chemical blocks. I have cut it out of everything I use. There are some others that are medium on the scale and low on the scale. Their risks are listed on the site. The risk of chemical blocks is too much for some people so they prefer physical blocks.
Physical blocks consist of Zinc Oxide and Titanium Dioxide. Physical blocks work by blocking the UVA/UVB rays. They work immediately after application, you don’t need 30 minutes. They are less water resistant and need more frequent re application if in the water. Physical blocks are less loved in general because they are thicker and have a white cast in general. I do feel physical blocks have made huge leaps and bounds in improving their textures and white cast effect. Physical blocks work when you apply them after your serums and moisturizer as the last step. I also feel this is one you have to let soak in for a good 5 minutes at least after applying before you move onto primer and foundation to avoid pilling.
So now I’ll discuss what I switched to as my favorites in the above picture. They are all chemical blocks, and I will explain why I use these particular chemical blocks. La Roche-Posay is a great manufacturer or sunscreens. The ones all sold in the USA however, are only physical or chemical with Oxybenzone. The Anthelios XL types with Mexoryl are amazing. They have the properties of chemical sunscreen we all love such as no white cast and thin texture. Mexoryl is the only chemical sunscreen to be rated as low risk by the EWG. It is sadly only available in Canada or Europe(with the exception of one product). You can get it shipped here easy, but can’t find it at Ulta. Ulta does sell one Mexoryl product(it’s center in the bottom photo). It’s the only one available in the US currently. I tried it, it’s thick, takes long to absorb and has a white cast so I can see it not being popular. Plus it was around $38 for a 1.7 oz tube. I got my non US versions from Essentual which ships from the UK. I’ve ordered from them many times with no issues. 
I have the La Roche-Posay Anthelios XL Lait Veloute and Ultra Light Fluid. Both are SPF 50+. The ultra light fluid replaces my old US one with Oxybenzone. It has a similar feel except it’s a tad thicker. If you put it over moisturizer it pills, if you put it on after vitamin C under moisturizer and let it absorb for a few minutes, it doesn’t pill. It’s a 50mL bottle. It’s light, and I use it for my face. It’s liquid and you have to shake it before using every time. It contains some alcohol which I don’t like, but so far hasn’t been drying or irritating to my face. I do use this around my eyes and it doesn’t sting like some other types. The other Lait Veloute is a 100mL tube that’s a thicker style lotion. I use this for my neck and body. It absorbs quick and no white cast.
The other sunscreen I alternate with is the Zelens Daily Defense, which is fairly new. Zelens is a chemical block, but it’s different in the fact that the chemicals are micro encapsulated to allow them to sit on the top of the skin vs being absorbed or binding with your skin. They still work by absorbing the UV rays but you don’t get the bad effects of chemical blocks being absorbed. It’s a 50mL tube and is more pricey than the others, but it’s great if you forgot your sunscreen below your moisturizer then you can add it last. This is a chemical block but you add it after moisturizer like a physical block because it sits on top of the skin. It also has vitamin C and other antioxidants to give you that day protection. The texture is a thicker lotion, it feels greasy at first but does absorb after 5 minutes. It leaves no white cast. I feel OK with these two choices as my main sunscreens even though they are chemical because they are in the safe range and perform well I highly recommend them all.
I have tried a few physical blocks as well to see if there was one above the chemical blocks. I tried MyChelle Sun Shield, MD Solar Sciences Mineral Tinted Creme 30 and CeraVe Face Lotion 30. I still want to try John Masters Organics and Drunk Elephants physical blocks. The MD Solar Sciences was nice as is was tinted and had no white cast. It was thin, but it was greasy feeling though so that was the main reason I didn’t like it. MyChelle was OK, it isn’t really thick or greasy and didn’t cause a big white cast. It just wasn’t better than the chemical ones I like, but it was a decent choice for a physical only block. It did pill if you added your foundation right after, it needed at least 5 minutes to sink in then this was avoided.
CeraVe Face Lotion SPF 30 with invisible zinc seemed great, it was thinner for a physical block, wasn’t that white on and wasn’t greasy at all. It however contains retinyl palmitate, a vitamin A derivative, that gives them the claim of having an anti aging sunscreen. Vitamin A helps with wrinkles. I know everyone has been claiming that Retinol and it’s derivatives can be used in the day now, but there was a study done showing that there’s the possibility that retinyl palmitate with exposure to sunlight causes a reaction which releases free radicals that can lead to cancer. Reducing free radicals is the goal of antioxidants and sunscreen to begin with, reduce oxidative stress on the skin. Free radicals and oxidative stress cause aging and the possibility of cancer. It was only in one study and the results have been debated about, it’s like parabens and sulfates, you have one study with a possibility of cancer so do you use it? Choice would be up to you. Personally, retinyl palmitate is such a weak version of vitamin A that it’s benefits don’t outweigh the risk to me. Why you would put it in a sunscreen is beyond me, a cream you put on only in day for use in sunlight… Same goes with any retinol type product in the day for me. At night retinol is great, it’s the number one anti aging product that does tackle all skin care issues, wrinkles, discoloration, acne, the list goes on. They have made great advances as well with retinol products to try to make it easier for all to use with less irritation. Make sure you use sunscreen every day especially if you use retinol at night or AHA.
I also used to use Shiseido Eye Sun Protection for the last 2 years, but when I switched to their new SPF 34 version I looked up the ingredients and it has more bad SD Alcohol 40 than it used to in it and it really dried and irritated my eyes. 

Check out the EWG summer 2014 sunscreen guide here.

Edit to add on 11/13: Check out this article which reviews the controversial sunscreen ingredients here. It’s an interesting read if you want to know more.

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