The finish hammer is used to make panels with very slight curvature. It can make a very smooth panel if used with care. In the past I used this method to hammer out some patch panels for a car fender. The finish hammer has a very slight convex curvature on its round head. Like all body work hammers, it should be used for body work, only. Never strike the hammer directly against the anvil or dolly.
The backing can be an anvil, leather, or rubber. It is good to experiment and see which works best for the metal and desired degree of curvature. Leather, an anvil, and hard rubber were experimented with as backing for this panel. This old piece of rubber conveyor belt worked best. It provided the desired curve with hardly any hammer marks.
The first step is to cut the panel out to a size larger than the finished part. It will be trimmed to size later. I rarely anneal a part that is hammered to a slight curvature. Usually I can get the curve I need without it.
Second, carefully hammer the part out. Blows that are too heavy will leave rings. Correct blows will leave small depressions.
Next, use a soft and flat rubber mallet to smooth out any imperfections. The part can be trimmed, welded on and polished, or it can be lightly sanded and riveted on, as I have done with my panel.