As summer approaches, the green of the forest becomes even more lush, and the sunlight filtering through the trees becomes dazzling.
Even with a parasol or hat to mitigate the effects, the sunlight still feels like it's touching your skin. So I made this using materials I felt comfortable with.
We've also introduced it on YouTube,
Please be sure to check it out!
A quiet day in early summer | Homemade sunscreen with calendula from the garden | Matcha jelly
Once you've learned the technique, you can easily change the oils and essential oils to suit your mood each year. Simmering "my favorite bottle of the year" in your kitchen is a perfect way to start the summer.
Unlike commercially available creams, this one tends to leave a white residue after application. It's best to apply small amounts frequently.
[Materials and Equipment]
Ingredients (for approximately 30g of finished product)
3g of beeswax
Either white or yellow will work. This time, we'll use white so that the finished product is white.
Calendula oil 20ml
Other plant oils can be used as a substitute.
・Purified water 5ml
Herb water or hydrosol can be used as a substitute.
• Plant-derived propanediol, approximately 1 ml
Natural moisturizing and preservative ingredients derived from corn
・6 drops of blended essential oil
See below. This step can be omitted if you prefer an unscented version.
Titanium dioxide 2g (1.6g is also acceptable)
Reflects UVB
• Zinc oxide 2g (1.6g is also acceptable)
Reflects UVA and UVB rays.
Breakdown of the blended essential oils (approximately 11 TP3T of the total amount)
3 drops of geranium (Egypt) / 1 drop of lemon balm / 1 drop of lavender angustifolia / 1 drop of frankincense.
This fragrance is designed for summer and also acts as an insect repellent. If you don't like it, you can substitute it with lavender, mint, lemongrass, or other scents you have on hand.
[Equipment]
• Heat-resistant beaker or heat-resistant glass container (two containers: one 50ml and one 200ml, the larger one is easier to mix)
• Stirrer (for coffee, glass rod, etc.)
• Small whisk
• Cream container
• Disinfectant alcohol (used for disinfecting equipment)
When handling powdered ingredients, white powder tends to scatter easily,
Using a tray or copy paper as a base makes cleanup easier.
vinegar.
Materials and equipment can be purchased here.
Rakuten Room
The difference between SPF and PA
When choosing a commercially available sunscreen, "SPF" and "PA" are key indicators. Let's first clarify what they represent.
Ultraviolet radiation consists of UVA, UVB, and UVC, and UVC is absorbed by the ozone layer and does not reach the Earth's surface. In other words, what we want to protect ourselves from is UVA.UVA and UVBis.
- SPF = An indicator of protection against UVB rays (expressed as a number).
UVB rays have a short wavelength and do not penetrate deep into the skin, but they are characterized by their strong effects. They can cause severe sunburn (including blistering), irritation, and wrinkles during prolonged outdoor activities such as at the beach or in the mountains.
- PA = UVA protection index (indicated by the number of plus signs)
UVA rays have a long wavelength and penetrate deep into the dermis layer of the skin. They cause age spots, wrinkles, and sagging, so it's important to protect yourself from them on a daily basis.
Tips for memorizing:If you remember that "PA = UVA" as a set, you'll naturally remember that the remaining SPF is UVB.
The difference between zinc oxide and titanium oxide
Two white powders are the main ingredients in homemade sunscreen. Both block ultraviolet rays.A "physical filter (ultraviolet scattering agent)" that reflects light.And since it only stays on the surface of the skin, the reassuring thing is that it can be removed with soap or your usual makeup remover.
- Zinc oxideReflects UVA and UVB rays (especially UVA). It's lightweight and tends to be used in large quantities, and can leave a slight white cast.
- Titanium oxide: Primarily reflects UVB rays. Less likely to cause a white cast than zinc oxide.
Combining both provides balanced coverage of UVA and UVB rays, and moreover,The white cast is reduced.That's a great point. If you're concerned about whitening, you can also make it using only titanium dioxide.
Incidentally, the "UV absorbers" commonly used in commercially available products are chemical filters that convert ultraviolet rays into heat and other substances before releasing them. While they are durable, they are not readily available to individuals, so they are not used in homemade products.
Points to consider when choosing:Larger particles, rutile-type, and coated zinc oxide are recommended as they are less irritating to the skin. While ultrafine particles are less likely to leave a white cast, their safety is a subject of debate, so choose based on your preference. Currently, coated zinc oxide products are not readily available to the general public.
【SPF guidelines
Adding 81 TP3T each of titanium dioxide and zinc oxide results in an SPF of approximately 11. Even adding both together doesn't bring the total to 22, averaging around SPF 15. This recipe aims for this SPF 15. If you want to reduce the white cast, you can reduce each to 1.6g.
Instructions and precautions for making it
Cream is made by emulsifying oil and water,When I have a block of free timePlease try it. It only takes about 15 minutes to make.
1.DisinfectThoroughly disinfect beakers, stirrers, and other utensils, as well as your hands, with disinfectant alcohol.
⒉ Prepare the water bath.: Place 3g of beeswax and 20ml of macadamia nut oil in a large beaker, and 5ml of purified water and approximately 1ml of propanediol in a small beaker (see notes below).
⒊ Melt in a double boilerPlace both simultaneously in a double boiler. Beeswax melts at 60-65°C. This should take approximately 3-5 minutes. If you don't have a hot plate, you can use a pot or frying pan filled with hot water for a double boiler.
⒋ EmulsifyOnce melted, remove from the double boiler and, while continuously stirring, gradually add water to the large beaker containing the oil. This should take about 5 minutes. Using a hand mixer from Daiso will make the process much easier.
⒌ Determine emulsificationOnce it has cooled to about body temperature and a thick consistency and "lines" remain on the surface, the emulsification is complete. It will be runny when hot, but will become creamy when cooled.
⒍ Add the remaining ingredients.Add the ingredients in the following order, mixing well after each addition: propanediol → essential oil → titanium dioxide and zinc oxide (2g each). Place a tray or paper underneath to prevent powder from scattering.
⒎ Pack into a container and it's done.Using a rubber spatula will help you transfer it neatly. It will be soft when freshly made, but after letting it sit overnight, it will become a smooth, spreadable cream.
Points to note
- [Important] In the video, the propanediol is added in step 6, but please add it together with the purified water in step 2. Because it is water-soluble, adding it at the end can cause separation. Since water and oil are less likely to separate when they are at roughly the same temperature, it's best to combine them from the beginning in a double boiler to minimize the risk of failure.
- It can be stored for about a month. It's best to use it up little by little every day rather than letting it sit for a long time.
- It can also be used as a makeup base. If you're concerned about stickiness, blot with a tissue after application before applying foundation.
- This essential oil is safe for children to use,The whole familyYes, you can use it.
For those who want to know more | How to understand SPF values
Now, let's get a little technical. While it's easy to think that a higher SPF number means better protection, it's actually not that simple and can be a bit confusing. Please continue reading only if you're interested.
First of all, SPF is not about "time""magnification"This is a numerical value defined by the Japan Fair Trade Council for Cosmetics. It indicates how much sunburn can be delayed compared to not wearing sunscreen, and is displayed as SPF10 if it delays it 10 times (Source: Japan Fair Trade Council for Cosmetics).
It's often said that "SPF 1 = approximately 20 minutes," but this isn't an officially defined number; it's based on the assumption that "someone's bare skin will turn red in about 20 minutes."guidelineHowever, this can vary greatly depending on your skin type and the intensity of sunlight, so please consider this only as a general guideline.
Another thing you should know is that the SPF value is"Applied quite generously"This means that the measurement is based on the international standard ISO 24444, which uses an amount of 2 mg per 1 cm² of skin to obtain the value (Source: Japan Cosmetic Industry Association). This is much more than the amount we usually apply. One study found that the appropriate amount needed for the face of a Japanese woman is about 1.12 g, while the actual amount used is an average of 0.56 g.About halfIt has been reported that this was the case (Source: Journal of the Japanese Society of Cosmetic Science).
In other words, the effects may not necessarily match the displayed numbers. That's why, rather than choosing based solely on numbers,Choose according to your lifestyleI recommend this.
- For short outings like commuting or lunch breaks, SPF 15-20 is sufficient.
- Spend most of your time indoors → SPF 10 is sufficient (for protection against UV rays coming through windows)
- For extended leisure activities such as at the beach, pool, or mountains, choose SPF50.
Furthermore, it's safer to combine these measures with protection such as wearing a hat or using a parasol.
【Reference Sites】
Journal of the Japanese Society of Cosmetic Scientists, Vol. 44, No. 2 (Research on Application Amount) https://www.jstage.jst.go.jp/browse/koshohin/44/2/_contents/-char/ja
Japan Cosmetic Industry Association "SPF Measurement Method Standards" https://www.jcia.org/user/business/guideline/spf
Cosmetics Fair Trade Council "Cosmetic Q&A (UV Protection Cosmetics)" https://www.cftc.jp/cosmeqa/04ultraviolet.html