This post seeks to answer a question that is frequently asked – “Why do your testing results differ from other sunscreen testing sites such as Consumer Reports?”
The answer is essentially, the tests done on the sunscreen are very different. I use a different testing set up compared to Consumer Reports and different sunscreen behave differently when exposed to differing external conditions (I used too many “differents” in that last sentence).
Sunscreen effectiveness is affected by many variables which determine the final protective properties a sunscreen formula will exhibit. % concentration of active ingredient, type of active ingredient, inclusion of inactive ingredients, and % concentration of inactive ingredients, all contribute to the overall product effectiveness (or lack thereof). This is influenced further by external variables such as method and quantity of applied sunscreen, substrate characteristics upon which the sunscreen is applied, exposure to moisture, oils, and overall temperature. When those external variables are introduced into the testing process, results will inevitably differ.
I have seen high % concentration mineral and chemical formulations perform worse than small % concentration formulations, and I’ve seen mineral formulations yield test results higher than chemical formulations (and vice versa). The inactive ingredients cocktail, the way the formula is mixed and dispensed, and to what segment of the market the product is intended, play a huge role in determining the look, feel, and ultimately, the sunscreens unique formulation.
In general, thicker more viscous sunscreen will yield higher protective results because the active ingredients tend to be less disturbed by heat, sweat, moisture, friction, and the resulting layer will tend to be thicker than a less viscous formula. This is why active sunscreen are typically thicker and greasier. For daily facial sunscreen, the formulations typically feel like liquids or very light non-greasy creams. However, they may not hold up as well when exposed to a harsher environment.
That said, it is the specific combination of active and inactive ingredients which plays a major role in how a sunscreen behaves, yet when the same sunscreen formula is tested using different procedures and methodologies, results may differ.
Consumer Reports testing methodology
Consumer reports tests sunscreen on the skin of an individual after soaking the sunscreen under water (you can see their testing method near the bottom of this page (How CR tests sunscreens): https://www.consumerreports.org/health/sunscreens/best-sunscreens-of-the-year-a7763432372/#how-cr-tests-sunscreens)
This water resistance test alone will very likely affect the inactive ingredient composition of the sunscreen formula to a great extent (as per the explanation between active vs. face sunscreen above). Differences in testing results could also be due to the uncontrolled variables introduced, such as the uneven application of sunscreen on the individuals skin, a persons skin type, temperature, mistakes in dispensing, heat, light, humidity etc. So in my very quick assumption of why the results differ so much, I would have to say that the CR water test drastically reduced the protective behavior of the lotion.
My testing methodology
I also believe my results may differ from those of Consumer Reports for certain sunscreen because my tests are conducted in a very different manner. I test in a highly controlled environment, taking care not to introduce any external variables (such as water, skin, or oils) into the equation. I apply the sunscreen to a microscope slide and use different test equipment and testing method compared to CR. Keep in mind that just testing using different methodologies alone will likely produce different results (as even differences in application layer thickness will change the final result even while keeping all else equal). It would be interesting to see if Consumer Reports tends to rate higher-viscosity, greasier lotions as more protective than thinner, less viscous formulas.
You can read my exact testing procedure here.
Its all about … MOARRR data
It is easy to get caught up in a X is better than Y mindset when choosing a skincare product, as we humans tend to believe what we choose is the best and most rightest choice in existence. But with such variety, and breadth of sunscreen products available to us, I find that the more data the better in helping us select a product that best fits our needs.
I consider the Sunscreentester website data the first step in selecting a sunscreen. Would I want to use a sunscreen product that tests poorly in a lab environment? No. I wouldn’t even consider it, and then find another which does. But, what if I had found a highly performing sunscreen? I would then take the next steps and consider the other characteristics of the product – intended usage, cost, feel, and safety (not necessarily in that order). Once I found a product which matched those criteria, I would then make a purchase and try it out.
I already have this X sunscreen and your results said it was bad, should I get rid of it?
Sometimes I receive a question about whether to throw away a subpar daily facial sunscreen, and my answer is almost always, if it has at least SPF 30-ish protection (and your goal is general sun protection during the day), and you enjoy using it – then just reapply often and apply lots of it. Even the worst sunscreen should be somewhat protective if reapplied often and in greater quantities. However, there may be tradeoffs to that suggestion. But making that choice is not in my domain.
