Black granite detergent stain removal African Black granite worktop used in a utility \ laundry room has been stained by detergents and alkaline used for the washers. The etch was too deep to be cleaned out so I had to polish it back and protect the stone for the future. 1 Stain on the left hand side of the sink is quite obvious. 2 General view as you open the door to the utility room shows the blemishes to the worktop. 3 After the polishing and protection the stone is as good as new. 4 General view shows no marks at all to the worktop. see more repairs