Neutral Soap and Water
For surface dirt and a quick clean up, use a neutral pH soap, water and a scrub brush. Since slate is a natural stone, it can be damaged by harsh cleansers that contain acids or alkaline products. Neutral soaps can include Ivory liquid, Dawn dishwashing soap and gentle hand soaps with no citrus extracts. The scrub brush will ensure that dirt or soap scum in the crevices of the stone is moved up and out.
Stone cleaners are available to handle any stone product, as well as stone cleaners specifically designed to clean slate tiles. A stone cleanser is designed to be neutral, and contains no soaps which could be problematic at attacking built up soap scum. Use a stone cleaner straight from the bottle with a scrub brush and rinse with fresh water.
Slate tiles do a fairly good job of disguising stains, but if an obvious stain has occurred due to hair color or other chemicals, a poultice can be used to remove it. Poultices are liquids designed to penetrate the pores of the stone and pull the stain to the surface where a stone cleaner or neutral cleanser can wash it away. For best results, cover a poultice with plastic wrap to seal in the chemical reaction.