It is easy to get over enthusiastic with the pressure washer. All is not lost. If the surface of your furniture is bumpy and rough due to power washing, you will need to sand the furniture’s surface. An inexpensive hand sander is usually sufficient. If the surface is really rough, start with a rougher sandpaper (60 or 100 grit) and then repeat with a finer grit (150 or 220). If it’s not so bad, you can start with the finer grit.