How to distinguish the front and back sides of a disposable mask

There are several methods to distinguish the front and back sides of a disposable mask, including the following: 1. **Color Differentiation**: Typically, the side with the darker color is the front, which should face outward; the lighter-colored side is the back, which should face inward toward the mouth and nose. 2. **Material Differentiation**: The front side (outer layer) is often designed to be water-resistant and dust-resistant, thus feeling relatively rough or textured to the touch; the back side (inner layer) is usually made of soft, breathable material, feeling smoother and finer. 3. **Metal Strip Differentiation**: The side with the metal nose clip is the front. The metal strip is used to mold the mask to fit the bridge of the nose and improve the seal; the back side does not have a metal strip. 4. **Pleat Direction Differentiation**: The pleats of the mask are usually designed to better conform to the facial contour. The side with the downward-facing pleats is the front, facing outward; the side with the upward-facing pleats is the back, facing inward.