For cleaning kitchen sinks we recommend using an abrasive Scotch-Brite sponge and a limescale remover such as Viakal (or simple white wine vinegar) to remove calcium build-up on the sink bottom. When a Corian® sink shows signs of staining it is not the material that is stained, but the encrustation of limescale that is stained by different foods (tea, coffee, carrots, wine, etc.). This is easy to verify: if you apply bleach diluted with water you will see the bottom of the sink turn white in only a few minutes; this means that the limescale has been bleached of the substance that had stained it. The problem is best resolved at the root cause by dissolving the limescale to eliminate any stains. Be careful: an abrasive sponge can ruin the chrome parts of taps and faucets or the drain cover so we suggest working far from the taps and removing the drain cover.