Some scourers come in a choice of colours and each colour represents how gentle or aggressive a scourer is. Here's the order from the gentlest to most aggressive scourer.... White (the gentlest, our recommendation on glass and sensitive surfaces)... then Red... then Blue... then Green (the famous green scourer, great for heavy cleaning and scrubbing)... then Brown and then Black (best known for stripping or extreme scrubbing). Regardless of what scourer you choose always test first on a surface to ensure suitability. Scourers are not suitable on some surfaces.