Hi, I have an aluminium outdoor table, but some of its surface coating have been pilled off. I would like to use black paint to re-paint the whole table, at the same time, to cover up the pilled off areas. I consider to use Spray Paint. I have two questions: 1) Do I have to do any preparation work before I re-paint it? 2) What kind of Spray Paint that I need for this purpose? Hope some paint/repair pro can give me some advice. I have attached a photo showing the pilled off paint area for your reference. Thank you.