A good paint job can transform a tired, worn-out piece of furniture into something fantastic. This even works on furniture that you've just grown tired of, or that does not fit your new decor. One step you may want to take if you want to paint furniture is to put a polyurethane finish on it to protect your work, but there are pros and cons to putting a poly finish on your painted furniture.
The Pros of Poly
Polyurethane is a tremendous product in terms of sealing and protecting wood. It's fairly forgiving in terms of application and will look good if you brush it, roll it or spray it. It comes in a variety of lusters, so you can use it to adjust the sheen of your finished piece.
If a polyurethane coat is applied over painted furniture, the paint will be thoroughly protected from scratches, dings and wear. A coat of poly can make your painted furniture look as good as new for a long time.
Another benefit is the ability of polyurethane to be polished. Sometimes painted furniture can look somewhat amateurish However, if you put a thick coat of polyurethane and let it cure, you can wet-sand the coat flat, and polish it with polishing compound to the exact shine you want. This process is what makes professional furniture look so fabulous; but you can accomplish it at home by polishing your poly coat with Ajax or Comet cleaning powder and water.
The Cons of Poly
The main argument against using polyurethane to protect your painted furniture comes into play if you ever plan to repaint the furniture. Polyurethane, especially oil-based polyurethane, does not allow other paint to stick to it very well. To repaint, you may have to rough up the surface, or strip it entirely.
Also, oil-based polyurethane takes a while to dry. In this time, it must be protected from dust that may mar its finish. Water-based poly dries much faster, but you need many more coats to achieve the level of protection oil-based affords.
For most painted furniture, a polyurethane coat is not necessary. Make sure you apply multiple coats of paint, and sand lightly in between coats. Keep the paint color on hand for touch-ups, and your painted furniture should serve you well.