White mask with letters, how to distinguish the front and back?

White mask with letters, how to distinguish the front and back?
1. Distinguish according to thread ends

The way to distinguish the front and back of a white flat mask is that, in general, the side with white thread on the white flat mask is the outside, otherwise, the side without the thread is the opposite.

2. Distinguish according to color

In order to make it easier for clinical use to distinguish between manufacturers, the color of the front and back of the mask is mostly different, the outer surface is mostly light blue or dark; the inner layer is mostly white or light.

3. Distinguish according to smoothness

Distinguish the front and back of the white plane mask can also be distinguished according to the degree of smoothness. The outer surface of the mask is mostly smooth due to its water blocking function; the inner layer is mostly made of materials with good breathability, close to the skin, which is conducive to breathing and is more delicate , Comfortable veneer.