The two part catalyzed paints dry by a chemical reaction and not just by evaporation. The end result is a very hard and durable finish. I did my steering wheel by first roughing up the surface with a fine grade sandpaper and then filling the cracks with an epoxy putty which was then sanded smooth. The whole wheel was then painted with two part epoxy primers and then a two part PPG primer surfacer and then sanded smooth. A few coats of uncatalyzed PPG basecoat were then covered with 2-3 coats of a PPG catalyzed clear. You need to be very careful with the catalyzed clear since it contains polyisocaynates which are highly toxic especially in a confined environment. The epoxy primer has no isocyanates but you should still be careful where you spray it and still wear a respirator when using it. I have a high volume-low pressure spray system that I used to do most of the work on my restoration, but for this small project, I actually used one of the disposable Preval spray systems and it worked out just fine.
George
