When you use epoxy it forms a barrier around your automobile that keeps out impurities. That is good however if you do not do take the proper steps to prep your automobile it also locks those mistakes in and can cause problems. If you drive down the road and you get a rock chip in the car that goes to the metal and breaks the Epoxy barrier, the point of the chip will start to get rust crepe because the epoxy will hold in the moisture. There is a time and place for epoxy like everything, become familiar with the product you are using.