are you using a machine or hand glaze? I use 3M imperial #05992 with a
foam pad and it works good on Black for me. There is an old product
called liqued Ebony thats still avalabel at the Dupont store here in my town.
Its black so it does't show in the cracks as much. It's made be cleanbrite co.
Another easy one is Ultra Care Products Super Finish.
good luck, Ron