Coloured sheet magnets adhere well to ferromagnetic surfaces, such as iron, steel or certain other metals. However, their effectiveness can vary depending on the type of surface and its condition. They adhere best to clean, smooth, and flat metal surfaces like steel shelves, filing cabinets, whiteboards, refrigerators, and metal doors. The magnetic force is strong on these surfaces, ensuring a secure hold. They also work well on painted or coated metal surfaces, as long as the paint or coating is not too thick, and the surface is clean and smooth. Some coatings might slightly reduce the magnetic strength, but they still adhere effectively. They can adhere to slightly curved or uneven metal surfaces, but the magnetic hold might be weaker compared to flat surfaces. Ensuring full contact between the magnet and the surface helps improve adhesion.
Coloured magnetic sheets do not adhere to non-metal surfaces such as wood, plastic, glass or concrete. For these surfaces, alternative attachment methods like adhesive backings would be needed. On rusty, dirty or greasy metal surfaces, the adhesion might be compromised. Cleaning the surface before attaching the magnet can help improve the magnetic hold.
Overall, coloured sheet magnets are versatile and work well on various metal surfaces, but their effectiveness depends on the cleanliness, smoothness and type of the surface they are applied to.