FAQs

Q: Do you have physical sunscreens in your shop?

A: We currently don't have physical sunscreen in our shop. However, we plan to bring it into our shop soon. 

 

Q: What is photostability in the context of sunscreen?

A: Photostability is the ability of a sunscreen to retain its integrity upon exposure to light. When you select a sunscreen, you will want to ensure that it doesn't degrade when the first UV ray hits your skin. That's why photostability is an essential quality for any sunscreen.

For example, avobenzone (most commonly used in Sunscreens in Canada and the United States) is photo-unstable and degrades even faster when exposed to light in combination with physical sunscreens like zinc oxide and titanium dioxide. It can lose up to 50-90% of its efficacy in the first hour of sun exposure. For this reason, avobenzone is now often formulated with photostabilizing chemicals such as bemotrizinole or octocrylene.

 

Q: What are the new generation UV filters?

A: They are second generation UV filters developed and widely used in Europe, Asia, and other regions except the United State. These new generation UV filters are remarkably photostable and some of them can help stabilize Oxtinoxate (old school UVB filter) and Avobenzone (old school UVA filter that is terrific but quite photo-unstable. 1 hour of sunlight exposure reduces avobenzone absorbance by 36%).

The following is examples of the new generation UV filters:

  • Tinosorb S or Bemotrizinol, INCI: Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine
  • Tinosorb M or Bisoctrizole, INCI: Methylene Bis-Benzotriazolyl Tetramethylbutylphenol
  • Tinosorb A2B, INCI: Tris-Biphenyl Triazine
  • Uvinal A Plus, INCI: Diethylamino Hydroxybenzoyl Hexyl Benzoate
  • Uvinal T150 or Octyl Triazone, INCI: Ethylhexyl Triazone
  • Ensulizole, INCI: Phenylbenzimidazole Sulfonic Acid
  • Mexoryl XL,  INCI: Drometrizole Trisiloxane
  • Mexoryl SX or Ecamsule, INCI: Terephthalylidene Dicamphor Sulfonic Acid

 

Q: How much sunscreen do you need for your face?

A: Two milligrams of sunscreen per square centimeter of skin.

As a rule of thumb, the right amount of sunscreen for your face is about 1/4 teaspoon, or 1/2 teaspoon for your face and neck, to achieve the SPF and PA rating on the sunscreen label. Therefore, a tube of 60 ml sunscreen should last 48 days or around a month and a half if you apply only on your face (not on your neck and body) once a day every day. However, if you reapply during the day as well, it will be used up sooner.

Tips: If you want to know whether you use it at an appropriate amount, you could write the date you start using it on a sticker and attach it to the bottle of your sunscreen. Then see how long it takes you to finish it up.

 

Q: How much is 1/4 teaspoon of sunscreen?

A: It is approximately the amount of sunscreen that you squeeze out onto your index finger, from the middle creases to the fingertip.

 

Q: Is the above method the same as the two-finger approach?

A: It's pretty much the same idea. The two-finger method is for head, face and neck combined. This can be done by dispensing a strip of sunscreen along the length of your index finger and middle finger (one strip on each finger). https://www.health.harvard.edu/skin-and-hair/how-to-apply-sunscreen-for-maximum-protection

 

Q: What is the PA rating?

A: PA stands for Protection Grade of UVA.

The PA grading system was established in Japan and is meant to inform users of the level of protection from UVA rays. The higher the PA ratings, the better UVA protection.

The PA rating system was adapted from the Persistent Pigment Darkening (PPD) method. This test uses UVA radiation to cause a persistent darkening—tanning—of the skin. PPD is tested on a variety of people, all exposed to UVA light. Every test subject is analyzed on how long it takes for their skin to tan. Researchers then compare the results between unprotected and protected skin.

PPD

PA

2-4

PA+

4-8

PA++

8-16

PA+++

16 or higher

PA++++