Painting Plywood? I have a wooden box made of 2 kind of plywood, and...

I have a wooden box made of 2 kind of plywood, and I want to paint the entire box black with spray paint. I don't want to see the wood grain when I am finished. What would I have to do so that it ends up as a solid black coat lacking all the grain in it (seeing through the paint). Would I hold to put primer on it, or is there a special instrument to do this? Thanks for any help.
Burning through concrete beside thermite?
Answers:    Would own been easier to ask this quiz before you built the boxes, that course you could have used MDO plywood and not enjoy any problems, but be that as it may . . . .

Sand, sand, and the sand some more. Then prime with an enamel under-body primer (the primer is latex, but its used for making ultra smooth surfaces for high-ranking gloss enamels)(may necessitate two coats, lightly sand between). Then I would not use spray paint, (it doesn't build enough). Brush (or roll) on several coats of paint (again lightly sand between each).
My shower drain?
Just sand the wood really good.