This is a common problem encountered by many cosmetics brands and buyers. Many people think that paint peeling is due to cutting corners by spray painting factories, but in fact, more than 80% of glass bottle paint peeling problems are caused by surface treatment and process control before spraying, rather than the paint itself. There are several reasons for this:

1.The glass surface is not thoroughly cleaned

During the production and spraying process of glass bottles, there may be residues such as dust, grease, fingerprints, and mold release agents. These pollutants will form an isolation layer. When spraying, the paint actually adheres to the oil stains, not to the glass. When subjected to friction or temperature changes, the entire paint film will peel off together.

The solution is to perform ultrasonic cleaning, alcohol cleaning, acetone degreasing, and ion air dust removal before spraying; Ensure that the cleanliness of the glass surface meets the spraying requirements.

2. Insufficient surface energy of glass

Although glass itself belongs to high surface energy materials, after long-term storage, its surface will adsorb pollutants from the air. This result will lead to insufficient wetting of the paint, uneven spreading of the paint film, and decreased adhesion.

The solution is to perform activation treatment before spraying: flame treatment, plasma treatment, corona treatment. Improve the surface activity of glass.

3. The glass surface has not been coated with primer or coupling agent

High end cosmetic glass bottles are usually not directly painted, and many manufacturers will first add a layer of "bridge", which is silane coupling agent and primer. The purpose is to grasp the silicon oxide structure on the glass surface at one end and the paint resin at the other end. Thus forming a stable chemical bond.

The solution is: for perfume bottles, essence liquid bottles, high-end skin care bottles; It is recommended to use a three-layer structure of silane treatment, primer, and topcoat to form a stable chemical bond.

4. Incorrect selection of paint system for glass bottles

Many customers require: matte effect, gradient spray coating, metallic texture, pearl effect; But different effects correspond to different paint systems. Common spraying systems include UV paint, PU paint, epoxy paint, and water-based paint. The most commonly used cosmetic glass packaging methods are UV spraying and PU spraying.

5. Insufficient solidification of glass bottles

Many paint films on glass bottles have dried on the surface, but the internal resin has not yet fully crosslinked; This is the most easily overlooked issue in the spray painting industry. The result is that the initial test was normal, but after one month, the paint began to peel off, the skin peeled off in a high temperature environment, and peeled off after wiping with alcohol. These issues become more pronounced during high temperature transportation, sea freight containers, and storage environments in summer.

The solution is to strictly control the UV irradiation energy, baking temperature, and curing time to ensure complete curing of the paint film.

6. Subsequent processes damage the paint film

Many glass bottles undergo screen printing, hot stamping, heat transfer printing, and assembly after spraying. If the process sequence is not reasonable, it is easy to damage the paint film. For example, if the screen printing baking temperature is too high, it will cause the bottom spray paint to soften. Final appearance: paint peeling, wrinkling, and delamination.

Glass bottles are prone to paint peeling after spraying, not simply due to paint quality issues, but rather determined by surface cleanliness, surface activation treatment, primer process, paint system selection, curing process, and post-processing flow. For high-end glass cosmetic bottles, a stable and durable spray coating effect often involves dozens of process controls and quality inspections. What truly determines the lifespan of spraying is not the final color, but the surface treatment technology that is invisible before spraying.