If you use a spray gun then it is important to use a hardener or else the finish will be dull looking.
But the same paint applied with a brush will be shiney and nice.
If you brush it, thin the paint a bit and apply 2 coats for lasting protection and attractive results.
I never had long lasting results from a spray can.
Dulled quickly and faded more.
The old timers who bought these tractors new would have scoffed at the fancy paint jobs we apply on them today.
Brush job was good enough.
Thanks to Ed Gooding for this great photo.