A black glass cook top is very beautiful but very difficult to clean because you will see the smallest traces of dirt and grease by the mirror effect. After much experimentation I found a good method. 1: First we remove the thickest grease stains with slightly damp kitchen paper. A paper dish cloth also works well as it has very spattered because they can wash and use it for the second or third time. Then the glass plate rub well with a non-abrasive scouring pad that is wet with a weak solution. Note that this is indeed weak because too much detergent leaves much soap residue behind which again provide a haze on the glass. After brushing decrease the wet sheet with a well squeezed viscose sponge (this takes a lot of water). You will see that the glass is already clean (almost). Any slight haze can be easily removed with a paper towel, a clean and dry kitchen cloth or microfibre cloth.