Here’s a new video on why DIY sunscreen doesn’t work. It’s a much more detailed version of my post on DIY sunscreen from a while ago. It’s a topic that’s quite important to me, since it’s one of those cases where having the wrong information can cause serious harm!
This video has been a bit delayed due to the rest of my life getting a bit hectic, but I managed to get it out before the Northern Hemisphere summer finished, so go me…
I bought a lapel microphone and some new editing software, so everything is a bit more polished I hope! Here it is:
Extra notes and references
Since I know there are a lot of nerds out there who like references and extra information, here are some of the sources for specific things I mention in the video (I got lazy with my citation style, sorry):
Dangers of UVA: Blog Post: Why You Should Protect Yourself From UVA
More info on sunscreen formulation
- SQ Wang & HL Lim (eds), Principles and Practice of Photoprotection: A very comprehensive book on everything related to sunscreen. Part II has a few chapters on sunscreen formulation.
- Realize Beauty, The Trouble With Making Your Own Sunscreen: Amanda Foxon-Hill, a cosmetic chemist, talks about the difficulties she encountered when trying to formulate a sunscreen. Her other posts are also very interesting!
- Kobo Products, Perspectives on Supplying Attenuation Grades (presentation): Info on zinc oxide photoreactivity and surface coatings, particle size and aggregation vs protection.
- BASF Creations Newsletter, Formulating with Zinc Oxide: Lots of information on how to formulate sunscreens with zinc oxide, including some information on dispersion and pH.
- Silverson, Manufacture of Suntan Creams and Lotions: Tips on dispersion from the manufacturer of some of the best industrial homogenisers used in sunscreen manufacture.
Sunscreens are very unlikely to cause endocrine disruption in practice: Journal of the American Academy of Dermatology (open access – quote: “Mathematic modeling indicated that it would take 277 years using a sunscreen containing 6% oxybenzone used at 2 mg/cm2 (the dose recommended for sun-protection factor [SPF] testing by the FDA) or 1 mg/cm2 (reported real-life use) to achieve the systemic levels of oxybenzone achieved in the study in rats”), Australasian Journal of Dermatology (looks at other filters apart from oxybenzone)
Nanoparticles in sunscreens are safe: TGA Literature Review (very comprehensive)
People stay in the sun for longer when wearing sunscreen: JID paper (open access)
Do oils increase UV penetration?
This is a topic that I thought deserved a longer write-up.
Studies have found mixed effects of oils on UV protection. In psoriasis patients, UV therapy is sometimes more effective after using an oil, and it’s believed that this is because scaly, opaque psoriatic skin can reflect UV, hence acting as its own “sunscreen”. The oil sticks the flaky skin together so the skin looks clearer, and is clearer to UV as well. Whether this happens significantly in normal skin is up for debate, but it’s certainly a possibility, especially if your skin is on the dry and flaky side.
For individual oils, for every source that reports UV protection, there seems to be another source that gives a negligible number or negative effect. For example, this paper has coconut oil with an in vitro SPF of 7, but New Directions found an in vitro SPF of 0.67 (SPF below 1 means worse than nothing). The same paper found an in vitro SPF of 7.5 for olive oil, but this paper found no effect on human volunteers (SPF ~1). I’m guessing it’s to do with the fact that in vitro measurements are pretty worthless for determining SPF, and that oils, like most other natural mixtures, vary in composition depending on the source and how it’s been processed. All this just seems to point to the fact you can’t rely on oils to give sun protection.
The sunscreen I wave around in the video is SunSense Sensitive Invisible, which was sent to me from Ego as a PR sample (this video was not made in conjunction with them or any other sunscreen companies, before anyone calls me a shill!). It still leaves a white cast but it’s more transparent than any other untinted physical/mineral-only sunscreen I’ve tried, although I prefer chemical or combination sunscreens. I’ll be doing a sunscreen review video soon!
SunSense sunscreen was provided for editorial consideration, which did not affect my opinion. This post also contains affiliate links – if you decide to click through and support Lab Muffin financially (at no extra cost to you), thank you! For more information, see Disclosure Policy.