You will not be hard pressed to find do it yourself (DIY) articles on the Internet to make your own sunscreen. DIY sunscreen formulation is not for everyone. There are a number of factors involved that requires a cosmetic formulating background in addition to very specific equipment. There are also “natural” products on the market that are claimed to have SPF protection, with only mere anecdotal evidence at best to back up those claims. I hope to clear up these issues and help to show that perhaps sunscreen should be left to the professionals.
Nanoparticles should be avoided in sunscreen. The reason for this is that the nanoparticles in zinc oxide break down in the presence of UVA rays and generate free radicals (1). The latest and greatest in sunscreen is the use of non-nano zinc oxide. These zinc particles sit on the outermost layer of your skin, the stratum corneum, absorb and reflect ultraviolet rays, protects your skin, all without the generation of free radicals.
Non-nano zinc oxide DIY recipes are all over the Internet. Many however are missing a very important key point, the DIY portion of how to properly disperse your dry ingredients fully into the liquid ingredients. To do this effectively and fully, you need what is called a high sheer mixer and a lot of knowledge. Without it you will not be able to accomplish even distribution of the zinc oxide in your sunscreen. What does this mean? Your sunscreen will have “holes”, allowing UVA and UVB rays to penetrate your skin, making it ineffective.
Let’s look at that concept a little bit further.
Measuring the viscosity and looking at particle size will not tell you about how your sunscreen will behave on the skin when it is applied, for this you need to examine the rheology of your product. Rheology is the study of the flow of liquids and crèmes; essentially the consistency and ease of spreadability (2).
If you are not properly and thoroughly mixing your sunscreen with the high sheer mixer, and the rheology or spreadability is not consistent, the thickness will not be consistent, this is where the holes in you sunscreen come into play.
You could send your sunscreen in for testing (mandatory when selling out in the marketplace), anticipating to have an SPF of 30 based on your ingredients, to learn that it only has an SPF of 10, and with holes.
Another thing to keep in mind is that a sunscreen testing labs only rub the products gently into the skin. The more vigorous rubbing that we typically do when applying sunscreen to ourselves and children results in a thinner application and an even more unreliable SPF protection factor .
In addition to the high sheer mixer, there are numerous other pieces of equipment that are needed. When working with zinc oxide, you need to be sure to have a particulate filter respirator. There are dangers to inhaling the particulates of zinc oxide (3). Hot plates, proper thermometers and other miscellaneous safety gear are necessary. The cost of all of this equipment is not for the faint at heart.
To reiterate, it is not enough to use a simple mixer or immersion blender to properly make your own DIY sunscreen using zinc oxide.
Carrot Seed Essential Oil
Often times carrot seed oil and carrot seed essential oil are confused.
Carrot seed essential oil is extracted from the seeds of Daucus Carota through steam distillation, labeled as carrot seed essential oil (volatile oil). Carrot seed oil is produced by pressing the oil from the seeds of the carrot plant, like you would produce other vegetable and seed oils, labeled as cold-pressed carrot seed oil or just carrot seed oil (non-volatile oil).
There is a myth that carrot seed essential oil carries an SPF of 40, but this is not accurate. Volatile essential oils carry an SPF of approximately 1-7, respectively. Non-volatile oils carry an SPF of approximately 2-8, respectively (4).
The product that was analyzed that perpetuated the carrot seed essential oil myth actually contains zinc, therefore the product has an accumulated SPF of 40 (5).
Red Raspberry Seed Oil
A study published in the Journal of Food Chemistry claimed that raspberry seed oil has an SPF of 28-50. The study makes the following bold claim: “The optical transmission of raspberry seed oil, especially in the UV range (290±400 nm) was comparable to that of titanium dioxide preparations with sun protection factor for UVB (SPF) and protection factor for UV–A (PFA) values between 28-50 and 6.75-7.5, respectively (Kobo Products Inc., South Plainfield, NJ)”(6).
The study however, points to no reference of proof of this large range (28-50) of SPF protection. Please do not take this one statement as confirmation that raspberry seed oil has this level of SPF. Remember as I stated above, non-volatile oils carry an SPF of approximately 2-8, respectively. This is likely the accurate SPF protection factor in this case.
Benefit VS Risk
When looking at the challenges that are presented with getting zinc oxide to stay properly and evenly disbursed, you can see that the risk is too great to have an ineffective DIY product. Essential oils as well as carrier oils do not in themselves carry an adequate SPF protection.
Do to all of these issues, we at Plant Therapy do not recommend making your own sunscreen, but rather to purchase a non-nano zinc oxide based sunscreen for yourself and your family.
(1) Nanoparticles, free radicals and oxidative stress. Retrieved from: https://www.researchgate.net/publication/49580656_Nanoparticles_free_radicals_and_oxidative_stress
(2) Houlden, R. (2017) Viscosity Versus Rheology : What’s the difference and why it is important to the formulation chemist. Australian Society of Cosmetic Chemists Conference 2017
(3) Zinc toxicology following particulate inhalation. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796768/
(4) In vitro sun protection factor determination of herbal oils used in cosmetics. Retrieved from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3140123/
(5) Efficacy Study of Sunscreens Containing Various Herbs for Protecting Skin from UVA and UVB Sunrays. Retrieved from: http://www.phcog.com/article.asp?issn=0973-1296;year=2009;volume=5;issue=19;spage=238;epage=248;aulast=Kapoor
(6) Characteristics of raspberry (Rubus idaeus L.) seed oil. Retrieved from: http://www.lotioncrafter.com/reference/oomah.pdf
Leslie Moldenauer, CHNC, HHP, Certified Aromatherapist, has been studying natural living and holistic wellness for over 10 years. Leslie is a trusted resource that covers essential oil safety and encompasses all that natural living has to offer. She is passionate about providing education and tools to help others make decisions regarding safety above all things when utilizing aromatherapy in the home.