The chips represent impacts from debris that gets kicked up by cars ahead of you. The idea is that this is a very well used helmet from an era where they weren’t new every few races. Similar to older cars that have a bunch of little chips on in the paint from gravel, etc. The colors below like blue and yellow imply that this helmet has been repainted multiple times. Now it is common to probably use a new helmet for each new design, but back then I imagine drivers kept the helmets a little longer and repainted or changed them instead of buying a new helmet. Likewise, back then the asphalt surface was probably not as ultra smooth and perfect as the circuits today, and gravel chips were probably a lot more prevalent.