If you are sourcing packaging for your skincare or cosmetic brand, understanding why ink struggles to adhere to glass will help you vet suppliers and avoid costly quality issues. Here are the three primary reasons why print fails on a glass cosmetic bottle. 1. Characteristics of glass bottles themselves The main component of glass is silicon dioxide (SiO ₂), which has a very smooth surface and no pores, unlike paper, plastic, or wood that allow ink to penetrate and form mechanical bonds. At the same time, when the glass surface is exposed to air for a long time, it will adsorb moisture from the air and form a hydroxyl (OH) hydrophilic layer. This invisible water film will reduce the bonding force between the ink and the glass, making it difficult for the ink to adhere firmly. The glass surface is highly inert. Ordinary soda lime glass has a smooth surface and low molecular polarity, making it difficult for ink to generate chemical bonding forces. With only physical adsorption, it is ea...