I really wouldn't worry about 'softness'. Mine's been in paint for about 6 weeks now.

Yesterday, I got a call from my wife, asking if the hood had always had a chip in it....(yeah, of course it has....that's how I painted it... )

Turns out she'd dropped a 2lb stainless steel lamp onto the hood, and according to her 'chipped' the paint.

When I got home, I checked it, and there was indeed, a 1/2 inch scratch.
It was barely noticeable, and right by a pintripe anyway, so I was able to break out the Mack and add a stripe to cover it.

Anyway, point is that the paint had not dented, dinged, or gouged, it had scratched exactly like any other cured auto paint would. I sprayed about 4 coats on that hood, so it wasn't thick, but it sure wasn't a thin coat either.

It's only enamel paint. Most cast iron bath tubs are finished (and re-finished) in enamels, and they are known for their hardness!

My experience - and the experiences of many others here - is that the stuff dries hard and solid.