The waterproof performance of a single waterproof self-adhesive sticker mainly depends on its three-layer structure：

1. Face Material: This is the “skin” of a label and the area where text and patterns are printed. Its waterproof performance is mainly determined by this layer of material. It usually adopts non-paper synthetic materials, which are inherently water-impermeable and resistant to water immersion.
2. Adhesive: This is the soul of a “self-adhesive” label. Waterproof labels use special waterproof adhesives (such as latex acrylic or solvent-based acrylic adhesives). Even after prolonged immersion in water, the adhesive will not emulsify or lose its stickiness, and can still maintain strong adhesion after drying.
3. Liner: Refers to the backing paper that is peeled off before application. Although it does not directly contribute to waterproofing, high-quality liners (such as glassine release paper) can ensure smooth die-cutting and peeling even in humid environments.