* Oily or greasy: Oil and grease repel nail polish.
* Wet or damp: Water interferes with the bonding process.
* Dirty or dusty: Debris prevents proper adhesion.
* Very smooth and non-porous: Surfaces like glass or some plastics are difficult for polish to grip.
* Residue from nail polish remover: Some removers leave behind residue that can interfere with adhesion.
* Silicone-based products: Silicone can create a barrier.
* Certain lotions or creams: Similar to oils, these can prevent the polish from sticking.
* Nail polish itself (after it's fully dried): That's why you need to file or rough up the surface before applying another coat if the previous coat is already dry.