A: If you are, as you say, a faux finisher you no doubt have materials that you favor for your techniques. What you need to know is how to prepare the surface to allow you to use them. Clean the existing finish with mineral spirits or TSP on nylon abrasive pads to remove any dirt, oils or wax, sand lightly and seal with Zinsser BIN white primer. You can go over that with whatever faux painting materials you are used to using, either oil based or waterbased. When you are done, you would be wise to add a coat or two of clear polyurethane. Use oil based polyurethane if you used oil based coloring materials. Either waterbased or oil based polyurethane can go atop waterbased coloring materials.