It depends on what you're trying to do. I have used the product Colin references as a
glaze medium, and extender, and a topcoat all depending on the finish.
For example, if I'm doing wood grain, I'll mix 1 part paint with 4 parts of the water based poly (
flat or
satin) and 4 parts water for the topcoat that sets the grain and board lines back in and then I'll go over the whole floor area with whatever sheen I want the wood to be.
Just note that when you paint over the floor again after the show, if you're limited to HD products, that you'll need to prime the floor and then go back over with black. Even the top
line paint at HD won't hold up to
foot traffic placed directly over a poly top coat.