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It's summer, and if your family is anything like mine, your days are spent outside. Whether it's work, play, or just lounging in the pleasant weather, we are in the sun, shade, or water pretty much constantly.
So needless to say, our skin gets a lot of sun exposure and of course, sunscreen always feels like a contentious issue: how do we balance protecting our children's skin from long-term effects of sun damage without blocking out Vitamin D and without slathering products laden with toxic chemicals on their skin?
I wrote last week about my recommendations for sunscreens to purchase, but today I want to share my recipe for DIY homemade sunscreen.
This is a homemade roll-on sunscreen stick, and I choose to make our homemade sunscreen this way because it's easier to slather on, it's not as messy (or greasy) as the homemade sunscreen lotions I used to make, and it's easier to toss in a bag when you're headed out.
But before we get to the very simple recipe, let's talk about two very important aspects of sunscreen: SPF and zinc oxide.
And of course I must pause here to remind you all: I am not a dermatologist, I have not had this sunscreen tested for SPF in a lab, and my favorite food to eat in the sun is watermelon. All cool? Fabulous.
First up: Sun Protection Factor (SPF)
Everyone's skin has a particular amount of natural protection against the sun and its rays. That's why lighter-colored bodies tan as the body's natural pigment, melanin, tries to protect the skin against sun damage. Of particular note is that everyone's skin is different. You've likely noticed that some fair-skinned people tan easily while others turn pink and burn before a tan even appears, while very dark-skinned people can, in fact, burn as well.
Thus, SPF (Sun Protection Factor) is a measurement of how much a certain chemical or mineral increases your natural sun tolerance. Many believe this determines how long they can stay in the sun according to how high an SPF they use.
For example, if I don't wear any sunscreen, I typically start to burn in the sun after about 20 minutes. So, 20 is my natural tolerance to ultraviolet light. If I apply a sunscreen with a SPF of 25, by that measure that sunscreen will give me approximately 20 x 25 minutes, or 500 minutes, of protection – that is, my natural tolerance multiplied by a factor of 25.
Yet we all know that I'll never get 500 minutes of protection from one application of an SPF 25 sunscreen. This is because it's not just a simple mathematical equation. Despite the calculation I just showed, SPF is not meant to help you determine duration of exposure, because the previous calculation doesn't factor in (ha, no pun intended):
- skin type
- the intensity of the different types of sun's rays (UVA and UVB, for example),
- atmospheric protection (e.g. altitude, air quality),
- the different ways we can wear sunscreen off (sweating, swimming, etc),
- our individual body's interaction with the chemicals added to provide SPF – some chemicals may degrade more quickly in one person's body than in another's.
So instead of helping you determine how long you can stay in the sun with sunscreen, SPF actually helps you determine how much UVB to which you will be exposed with sunscreen, regardless of length of exposure. An SPF of 100 blocks about 99% of UVB rays, while SPF 50 blocks 98 percent. SPF 30 blocks 96.7 percent, SPF 15 blocks 93%. Many dermatologists say that a 15 or 30 SPF sunscreen is sufficient in most cases for most individuals, since you can see that an SPF 100 sunscreen protects only about 6% more than an SPF 15.
(In my opinion, the only time the extra protection would be needed is when you are dealing with prolonged exposure at high altitudes when you have no other protection available – say, you're going to be hiking in the mountains above timberline over a reflective snow-pack and will be wearing a thin shirt).
The Two Types of SPF & Important Facts about Zinc Oxide
Manufacturers create SPF in two different ways: by adding chemicals or by adding minerals.
Chemical-based sunscreens work by adding chemical compounds to the sunscreen base which absorb ultraviolet light, such as oxybenzone, oxtinoxate, and octisalate. These chemicals must be absorbed into the skin in order to be effective, which is why many sunscreens instruct you to apply them at least 20 minutes before sun exposure.
Mineral-based sunscreens work by adding inorganic material that reflects, scatters, and absorbs UV light, such as zinc oxide and titanium oxide. These types of sunscreens sit on top of the skin, so can be applied at the time of sun exposure.
Some sunscreens have both chemical and minerals, so read your labels carefully to know exactly what you're getting.
Now, the important thing to note is that mineral-based sunscreens automatically sound like a better way to go for naturally-minded families, and they often are, but you do need to be aware that not all minerals are created equal. (Why, oh why aren't these decisions ever just simple and straight-forward???)
The one thing of which you need to be aware when it comes to minerals is particle size. If the particles are small enough to fit into your pores, they will be absorbed – and zinc oxide has been linked to organ damage if inhaled, ingested, or absorbed into the bloodstream. These nanoparticles are created by a micronization process (merely “the process of making something tiny”), and many brands will label their products with “nano” or “micro” in the ingredient list.
The upside side, however, is that sunscreens that use nanoparticles don't leave the same white sheen behind and thus it's more attractive to some consumers. (There are a few exceptions to this as technology advances, but by and large this simplification stands.)
So, it's your choice – you can either have a whiter, more obvious sunscreen or a less obvious sunscreen that may be absorbed into your system.
But that brings us very conveniently to this homemade version, as one way I deal with the white sheen of non-nano zinc oxide is by tinting the sunscreen. It tames the white glare and provides a natural, sun-kissed glow all at the same time. It also works well on darker skin to help offset the purple tint that can happen with white powders on very dark skin. 🙂
So, with all that, what are we waiting for? Let's make homemade sunscreen – roll-on style!
Homemade Roll-on Sunscreen Stick
- 25 grams beeswax, about 1 ½ tablespoons beeswax pastilles
- 40 grams shea or mango butter, about 3 tablespoons
- 50 grams coconut oil, about 3 ¾ tablespoons
- 20 grams cocoa butter, about 1 ½ tablespoons
- 30 grams zinc oxide, about 1 ½ tablespoons (see where to buy non-nano zinc oxide)
- cocoa powder, 1-7 tablespoons (optional) - the tinted sunscreen in the picture above used 5 tablespoons
- Melt all ingredients except zinc oxide and cocoa powder together in a double-boiler (or in a small saucepan set inside a slightly larger saucepan with simmering water). If you must heat the ingredients on direct heat, be sure to use the absolute lowest setting your stove will allow.
- When all ingredients are melted, remove from the heat and stir in the zinc oxide and cocoa powder, if using. Be careful not to breathe in the zinc oxide powder.
- Make sure the mixture is well mixed, especially if you're using large amounts of cocoa powder, then pour the mixture into your deodorant tubes.
- Let stand until completely cool and very firm, 6-12 hours.
- Store in the refrigerator for 6-12 months. Carry in any bag, but word to the wise: if you will be in a warm location, keep the sunscreen in your cooler or store in a zipper-top plastic bag out of the sun, as the sunscreen will soften as it warms.
- Apply liberally and reapply anytime water no longer beads on top.
- For SPF 2-5: Use 5% zinc oxide
- SPF 6-11: Use 10% zinc oxide
- For SPF 12-19: Use 15% zinc oxide
- SPF 20+: Use 20% zinc oxide