How do you deal with cracks, I've heard of JB Weld. Which JB Weld Product should be used. Same goes for Bondo.
I don't know but if you try facebook and type leather fire helmets there is a crap ton of guys who fix and repaint helmets. Plus a ton of guys willing to give advice.
I used JB weld on my Cairns N5A.. applied straight up JB weld, nothing fancy. Smoothed it out, sanded it down and painted it. Good as new