The helmet number 3 is the most interesting one for now. It had its original paint removed and repainted with a strange black one very thin, thats why there is bare steel on some spots but hasnt rusted yet since the paint probably had something anti rust in it. You can clearly see the line on bottom right shirt where the edge hasnt been repainted by this paint.
4. This one has nothing under, just a shell with some remains of who knows what.