防曬霜分為物理防曬和化學防曬兩種：
物理防曬，顧名思義，就是利用物理學原理，這種防曬霜的原子微粒是片狀的，當在臉上塗開的時候，就像鏡子一樣，反射陽光，達到防曬的目的。
二氧化鈦和氧化鋅就都屬於物理性防曬成份。它們可以在皮膚上形成保護膜，使得紫外線無法穿透皮膚表面，兩者皆可提供周全的UVB防護，其中以氧化鋅更能阻絕UVA。典型的物理性防曬成份呈白色、糊狀，且在接觸到水以後變成藍色。
但是這一類產品也有一定局限：對於膚色較深的人來說，其潤色效果可能不太自然；對於膚質較乾的人來說，不夠滋潤；不適合做全身防曬；必須使用卸妝產品幫助卸除乾淨，等等。
Titanium dioxide﹝二氧化鈦﹞：可以阻隔UVB和部分的UVA，但是對長波長部份的UVA無法完全保護。欲達到較高的SPF時擦起來會有些白白的。
Zinc oxide﹝氧化鋅﹞：可以幾乎阻隔掉所有波長的UVA和UVB。但是因為塗起來會白白且粘粘厚厚的一層，所以限制了它的實用性。後來有些廠商發展出粒子較小的氧化鋅分子，即所謂的Z-Cote，使用上塗在皮膚是透明的，改善了上述的缺失，同時還是可以對所有波長的UVA和UVB進行防護。
物理性防曬是利用反射光線的原理來達到阻隔紫外線的作用，這兩種成分能夠均勻的分散於油脂成份中，塗於皮膚後，因為其分子量較大並不會被肌膚吸收，而且經實驗研究指出，物理性防曬劑非常穩定，即使經過120分鐘的紫外線照射後，防曬成分依然穩定不會變質。
這種光穩定性及不被肌膚吸收的特性，使得物理性防曬劑為敏感性肌膚、異位性肌膚及嬰幼童肌膚最佳選擇。
可是物理性防曬劑也並非完美無缺，物理性防曬劑在質地比較厚重、滋潤，對於油性肌膚、混合性肌膚、青春痘肌膚並不適合使用。而且使用物理性防曬劑後，膚色會略帶白色的上粧感覺，因此對於某些不習慣上妝的男性或青少年來說需要一段時間來適應。
物理性防曬-Sunscreen
The sunscreen lotion divides into physics and chemistry. Physical sun protection uses physical principles. The lotion’s atomic particles are like a sheet, When you spreads on the face, it works like a mirror to reflect sunlight for skin protection.
Titanium dioxide and zinc oxide are all the ingredients of physical sunscreen.
A protective film can be formed on the skin. Ultraviolet rays cannot penetrate the skin. Both can provide comprehensive UVB protection. zinc oxide can block UVA especially. The typical physical sunscreen ingredients will appear in white and mushy status. It will turn blue when exposed to water. But such products still have some certain limitations for people with darker and drier skin. They need to use cleansing products to help clear…Etc.
Titanium dioxide can block UTA and some UTB. But it cannot fully protect long wavelength’s UTA. For achieving higher SPF but it will appear white.
Zinc oxide can block all the long wavelength’s UTA and UVB. Because It will appear white and thick when you spread so some company develop smaller zinc oxide molecules. It’s called Z-Cote, when you spread on the skin will appear transparent. It improve the above lack and also have protection for long wavelength’s UTA and UVB.
Physical sun protection is made use of the principle of reflection to block ultraviolet rays. These two ingredients will be dispersed in the oil component. Because of its large molecular so it will not be absorbed by the skin. According to experimental research, it is very stable. After 120minutes’s ultraviolet radiation the ingredients are still stable and will not deteriorate.
Stable and not absorbed by the skin, so physical sunscreen is the best choice for atopic skin and baby skin. But the physical sunscreen’s textures are thick and moisturize so not suitable for oil and combination and acne skin. And also will appear white makeup when you spread. So it need some times for those who are not used to make up to adapt.