The masks are made of three layers of non-woven materials, and the front and back sides need to be distinguished, otherwise they cannot be worn correctly, and the protective effect that the masks should have lost.
The front and back of the mask can be distinguished by metal strips, creases, colors and fabrics:
1. The metal bar is distinguished. Generally, the metal bar is on the top, and the side protruding outward is the outside, and the opposite side is inside.
2. The creases are distinguished. The upward side of the crease is the inner surface, and vice versa is the outer surface.
3. Color distinction, the front and back of the mask are mostly different in color, the outer surface layer is mostly light blue or dark color, and the inner layer is mostly white or light color.
4. According to the degree of smoothness, the outer layer of the mask has a waterproof function, mostly smooth surface, and the inner layer chooses materials with good breathability, close to the skin for breathing, more delicate, and the veneer is comfortable.