Everyone has seen it happen; a car gets finished and it looks perfect. A few months later, sanding scratches start to show up, and everything about the paint looks shrunk up and dried out. It’s a terrible feeling to see this after all the hard work and countless hours.
There are a few really basic things that can help you completely avoid this problem, and have the confidence the work will look fantastic for a long time.
- The filler. The majority of the block sanding should be done with 80 grit. 40 grit can and should be used to get the rough shape in the filler while it is drying, but the bulk of the block sanding should be with 80 grit. Do not re filler over anything coarser than 80 grit. Even if there is one stray 40 grit scratch, sand it out with 80 grit. Although filler barely shrinks, it’s still better to play it safe. Be strict about this.
- Scratches. Absolutely do not fill left over scratches before primer, especially with glaze. If they can’t sand out, feather out the area and use regular body filler to tightly fill the spot. Let it dry and block with 80.
- Primer. A high quality polyester primer is extremely important. Finish the filler in 120-150 grit. Don’t abuse the polyester, spray descent medium-wet coats, do not hammer it on. I like the brands Spies Hecker, Glasurit or Standox.
- Sanding steps. Be very thorough with every sanding step. Use plenty of dry guide coat between grits. Don’t cheat, and don’t skip a thing. That is key. The grits I use in polyester are 100, 220, 400.
- No urethane primer. If you wish, the project can be sealed and wet sanded. But there’s no need for a ‘final prime’ with urethane. Do not add the completely unnecessary solvent.
These are just a few guidelines for a lot of reassurance. As always, be thorough and pay attention to every detail.