No, but they make a GLAZE that you can paint OVER flat paint to make it glossy. You can't make a matte finish paint glossy--you can only add another coat of a gloss finish (transparent) over top of it.

You can't but what you can do is go to the paint store and buy paints that people have returned. If people buy it and don't like the color, they take it back. You can get these paints for under $2.00.

I'm on a budget and am forced to use paint I already have, which happens to be flat wall paint...I need Simi-gloss. Do they make an additive that I can add to flat paint to make it a gloss finish?