Why should we correctly distinguish the front and back of the mask?
Many people may think that the positive and negative sides are the same, as long as Dai Yanshi is done. In fact, this is not the case. The function of the front and back of the mask is different. Many masks use a three-layer design type, in which the filter layer for filtering bacteria is located in the middle, the outer layer is a waterproof layer, and the inside is a water-absorbing layer.
If it is worn backwards, the water-absorbing layer will become a waterproof layer, and the waterproof layer will become a water-absorbing layer, which will cause the saliva to adhere to the surface of the mask, and the more it accumulates, the wet mask may become wet and the mask will lose its filtering function.
How to distinguish the front and back of a mask
How do you distinguish the front and back of the mask?
First of all, let ’s distinguish between the top and the bottom, "the one with the metal bar is the top", because the metal bar can be used to adjust to fit the nose.
After the above is determined, let's judge which side is outside and which side is inside.
I listed the characteristics of several common disposable masks, you can judge the number of seats.
Judge by color
Generally, we see blue medical surgical masks, the blue side is the outside, and the light (white) side is the inside (attached to the face). There are also pink and black, which can also be judged according to this principle.
Judging by printing
If the logo or brand name is printed on the mask, it is easy to judge that the embossment of the logo or brand name is usually printed on the outside, and then you can know which side is outside by looking at whether the word is positive.
Judging by the direction of the fold
What if the mask you bought is pure white and has no printed fonts? It's okay, we have another ultimate judgment method: look at the direction of the fold!
There are two cases of mask wrinkles:
The direction of the folds is outward.
There is also a kind of mask with four folds, which is better to judge. You open it naturally, and the middle one is convex outward, then this side is outside. In fact, it's easy to think about it, so that our nose and mouth have a certain space to breathe.
After being stretched out, the direction of the upper two folds is upward, and the direction of the lower two folds is downward.
Judging by the fabric material
I did n’t say it at the beginning of the article. The design of the front and back of the mask is different. The inside is the water-absorbing layer, so the materials on both sides are also different. We can use this to judge the front and back of the mask.
The obvious grid looks a little tough, this side is the waterproof side
There is a soft fabric sense inside.
You can do a simple experiment: each drop of clean, pure water on the surface, the hydrophilic (water will wet the surface) side is facing inward, and the hydrophobic (water is not wet, spherical) side is facing out.
First, it can be interpreted by color: the dark color is outside, and the light color is inside; secondly, it can be judged by printing.
If you buy a pure white mask without printing, you can judge by the direction of the fold. If it is three-folded, then the direction of the fold is downwards; if it is four-folded, then the middle piece after the expansion is convex, that is, outside. In addition, after the expansion, the direction of the upper two folds is upward, and the direction of the lower two folds is downward.
Finally, we can also distinguish the front and back by materials. There is an obvious lattice, which looks a little tough, and it is a waterproof surface on the outside; a soft fabric feel is the water-absorbing surface inside.