When prepping primer for paint, it is very important to make sure all remaining scratches are caught and sanded out. There is nothing worse than sand scratches showing through paint, or spraying sealer and then finding out there were scratches missed. How to avoid this?
- First, using plenty of guide coat is very important. The guide coat has to be in every scratch in order to see the scratches.
- After sanding, wet the panel down with wax and grease remover. This is very very very important. The black guide coat hides in the left over scratches it is dry. As soon as it gets wet, the guide coat lights up.
- While the panel is wet, circle, with a pencil, all of the remaining scratches.
- Use a blow gun to dry the panel, and finish sanding out the scratches.
- In the picture below, the top picture is dry, the bottom picture is wet with wax and grease remover. You can see how much the scratches show up, which might have been missed otherwise.