The sponge-like Mr. Clean Magic Eraser doesn't contain any type of cleaning solution or chemical. The cleaning sponge is made from melamine foam, a hard polymer. Although it appears smooth on the surface, the foam actually has a very porous texture that removes dirt by scraping it away in much the same way as fine-grit sandpaper. The holes in the foam also grab loosened dirt, holding onto it rather than spreading it across the surface being cleaned. Because of their texture and composition, melamine sponges should not be used on your skin or glossy surfaces such as your car's paint.
The Magic Formula
The original Mr. Clean Magic Eraser contains no cleaning chemicals and uses the foam alone to remove dirt. Some versions of the product do, however, contain cleaners. The bath scrubber eraser contains a soap scum remover that works in conjunction with the foam's texture to remove the soapy film from tubs, showers and sinks. A kitchen form of the product is also available and is infused with Dawn brand dish detergent for grease removal. Other versions of the product include one with an attachable handle for more leverage when cleaning large areas, and a "select-a-size" option that allows you to break the melamine foam into smaller pieces based on the size of the area you have to clean.