
It is possible to paint Giani over other painted counters if they are sanded or de-glossed. You do not have to sand down to the original countertop, just rough up any type of top coat or epoxy with a fine grit (600 grit) sand paper. Remember to clean off any sanding dust.
Once this is done you can begin the steps of Giani- 1. Roll primer, 2. Sponge minerals, 3. Roll Top coat... and wallah! You will have a new shiny granite finish!