- Waterproof Substrate: The Core Carrier of Sticker Durability
The substrate is the “skeleton” of a sticker, and its inherent water resistance directly determines the sticker’s basic performance. Common waterproof substrates for cosmetic stickers include:
PET (Polyethylene Terephthalate)
PET is one of the most widely used waterproof substrates in cosmetic stickers. Its molecular structure is stable, resistant to acids and alkalis, and withstands a wide temperature range (-40°C to 120°C). It offers excellent water resistance—remaining intact without warping, wrinkling, or dissolving even after prolonged contact with water or oils in skincare products.
In practical use, PET substrates are ideal for bottles (e.g., toners, serums) and tubes (e.g., mask cream tubes) that are frequently exposed to liquids. For example, many Japanese skincare products use PET for their round brand stickers—ensuring that, even if the bottle is splashed with toner, the sticker stays flat, with text remaining clear and smudge-free.
PET is also eco-friendly, FDA-approved for direct food contact, making it safe for lip and face cosmetics packaging. It offers high print color fidelity, perfectly presenting metallic tones, gradients, and other premium visual effects for brand logos.
PVC (Polyvinyl Chloride)
PVC substrates excel in both water resistance and flexibility, allowing them to adhere smoothly to curved surfaces (e.g., round caps, curved bottles). They are wear-resistant and tear-resistant, making them suitable for items that are frequently handled or displayed outdoors (e.g., cosmetic sample stickers at trade shows).
However, regular PVC may release harmful substances at high temperatures, so it is mostly used for exterior stickers that do not directly touch skin (e.g., perfume box labels, gift set outer labels). Environmentally treated “medical-grade PVC” can be safely used for some skincare packaging, retaining its waterproof properties while meeting safety standards.
Synthetic Paper (PE/PP Synthetic Paper)
Made from polyethylene (PE) or polypropylene (PP), synthetic paper combines the printability of traditional paper with the waterproof properties of plastic—earning it the nickname “eco-friendly waterproof paper.” Its smooth surface allows for fine detail printing, and it resists folding and oil stains. It is perfect for products requiring a paper-like texture while remaining waterproof (e.g., vintage-style stickers for natural skincare).
For example, organic or “natural” cosmetic brands often use ivory-colored synthetic paper for round stickers, preserving the warmth of paper while resisting water stains from bathroom sinks.
- Waterproof Coatings: The “Invisible Shield” for Enhanced Protection
The substrate’s water resistance alone is often not enough. Adding a surface coating can further improve resistance to water, scratches, and chemical corrosion. Common coating techniques include:
Matte/Gloss Film Coating (OPP/PE Film)
A transparent film layer (matte or gloss) is applied to the surface, forming a physical barrier that prevents water penetration. Gloss films (OPP) offer high transparency and enhance shine—ideal for highlighting metallic brand logos—while matte films (PE) create a soft, frosted effect, perfect for understated premium skincare styles.
This technique is widely used on lipstick tubes and foundation bottles. Even when splashed with makeup remover or alcohol, the film protects the underlying print from fading or smudging.
UV-Cured Coating
This process uses ultraviolet light to rapidly cure the coating into a hard, waterproof film with excellent scratch resistance and anti-yellowing properties. UV coatings outperform standard films in water resistance and can enhance texture—for example, spot UV can make logos stand out in relief. Ideal for premium cosmetics requiring long-term preservation (e.g., perfumes, luxury creams).
For example, some luxury perfume bottles feature round stickers with UV coatings that remain smooth and glossy in humid bathrooms, leaving no watermarks.
Nano Waterproof Coating
A newer technology, nano coatings cover the surface with a molecular layer that creates a “super-hydrophobic” effect—water droplets bead up and roll off without penetrating the substrate. This is ideal for extremely humid environments (e.g., body lotion or shower gel bottles) and maintains breathability to prevent detachment caused by trapped moisture.
- Waterproof Adhesives: The “Invisible Bond” for Secure Attachment
A sticker’s water resistance depends not only on its substrate and coating but also on its adhesive. If the adhesive fails upon contact with water, even the most waterproof substrate will peel off. Common waterproof adhesives for cosmetic stickers include:
Solvent-Based Pressure-Sensitive Adhesive
Using an organic solvent carrier, the adhesive dries into a dense molecular structure with excellent water resistance and strong adhesion to PET, PVC, and other plastic substrates. Suitable for long-term applications (e.g., permanent bottle labels), it resists softening or dissolving even after repeated contact with water or skincare products.
Hot-Melt Adhesive
Applied in molten form to the back of the substrate and solidified upon cooling, this adhesive excels in high and low temperature resistance. Solvent-free and eco-friendly, it is ideal for food-grade cosmetics (e.g., lip balms, lip masks). Even in humid conditions, it retains its tackiness without releasing harmful substances.
Acrylic Adhesive
Made primarily from acrylic esters, this adhesive is transparent, aging-resistant, and highly water- and chemical-resistant (withstanding alcohol, fragrance oils, and other skincare ingredients). It is commonly used for stickers that come into direct contact with product contents (e.g., jar seal labels), ensuring the adhesive remains stable and non-contaminating throughout the product’s shelf life.
