Seriously, you want to know why body work costs so much? It takes hours upon hours to get the car prepped for the paint. And if you are spraying multiple colors? Do the math.
This picture really reminds me of my dad. He would spend countless hours painting cars in the garage. You're right, he would complain of the prep time a lot! The end result always turned out well, however, so it was worth the time. http://www.ascentinnov.com/microsoft-dynamics-ax.html
