ok, cool. If you have flaking/peeling paint, I would recommend going to the metal. When you paint a car you usually use a sealer first, then your base coat, then you clear it. Clear is what makes it shiny and protects the finish from the elements. Base coat has no UV protection. So if you clear has peeled or "died" and started coming off, then your base coat is shot. Ill try to step out what I would do
Getting ready to prime:
-Work one panel at a time. Unless you live somewhere that has little to no humidity and you know you can finish large portions at once. The more bare metal you have, the more chance you have of flash rusting. Even the oils from your hands can create a film that primer/paint will not stick to. Wear rubber gloves
1) strip all paint off using at least 80 grit on a DA sander. I will sometimes use 36-40 grit on a high speed sander to cut threw the first few layers faster, then finish it up with 80 to the metal.
2) clean panel with a grease and wax remover.
3) use a direct to metal primer. Not all primers are designed to adhere to bare metal. What I usually do is hit it with a DTM epoxy primer and then 3 coats of 2k high build. Giving about 15 mins of flash time in between coats, depends on you temp. The colder it is, the more flash time needed.
-there are two types of body filler I use. One is a body filler, z-grip, rage, rage gold, etc) that is used for filling the larger dents. It is stronger and designed to fill. The other is called a polester putty. I use it after I have worked the body filler to the shape I want(easysand, dolphin glaze, icing, metal glaze, etc etc). Its more for finishing off your repair. Filling heavier sanding scratches from the bondo work.
1) pull out or dolly out as much of dent as you can. Try and get the panel as straight as possible before you grind off the paint, while you can still see it. You dont want any high spots, would rather it be a tad low. You can use a straight edge to show you how its shaped. If it teeters over a high spot, work you metal some more.
2) Grind off the paint or primer to the bare metal. Body fillers are not designed to stick to paint (Polyester putties can be applied over sanded paints/primers). Then I would feather out the paint edges before applying body filler.
use your bondo spreader to apply the filler. Make straight pulls applying. Tight wiping it will help get rid of pin holes.
3) I use 36-40 grit air board paper torn in sections to fit my sanding block. This will cut the filler down fast and straight.
4) when I get it almost to the shape I am happy with, I will finish it off with 80 grit paper on my block
5) Once your finish making it look and feel right, I would 80 grit all the area that has been repaired on. Making sure I caught any heavy sanding scratches that I made earlier with the 36-40 grit. Then I would tight wipe a coat of the polyester filler over the entire repair area. This is going to make a nice finish to the repair getting it ready for primer.
6) I cut this wipe down with 80 grit the finish it off with 180.
7) I prep the entire area with 220-320 grit before I prime. I sand 3-4 inches past all sanding scratches made while repairing.
-you can dust some black spray paint, misting it really, over all primered areas. This helps show low and high spots while sanding. Also, tape off anything that you do not want sanded that the sand paper will come close to while sanding. Run a piece or two over any moldings or trim to protect them.
1) block sand all areas that have had bondo repairs performed with 320
2) I would 320-400 the entire vehicle with a DA sander
3) If I am doing it to be really nice I will 600 the entire vehicle after that to get rid of the 320 scratches. You usually dont have to do this unless you are painting it black or are going to cut and buff the car to a more mirror finish afterwards.
4) Blow it off really good, everywhere, inside and out
5) after all sanding is done, every nook and cranny has been sanded, I would pull the car out and hose it off. They sell a paste called scuff stuff, scuff it, etc. These are a paste that helps not only scuff the panel some more in places that are harder to get to with sand papers, but they clean the panels also. So, I would get some red scotch pads, and tear them in half, put some scuff stuff on the pad then panel by panel, I would scrub every square inch of each panel. When you think you have it good enough, Id do it again. Rinsing off each panel as I go because it leaves a film if you let it dry that takes more scrubbing to get off.
6) after that I would mix up some regular Dawn in a clean bucket and wash the entire car. I would spray out any area that might be holding dirt or dust. Again, do one panel at a time. If you let dawn dry on the panel, it will leave a film that you will have to re-wash to get off.
7) once the car has dried completely, I would blow it off really good. Never can blow it off enough. everywhere dust can hide.
8) Tape off everything you dont want paint on. use a wax backed paper for areas right next to where you will paint. These papers will not allow the paints to saturate thru and get onto things that you dont want paint on. Imagine getting news paper wet, it bleeds thru. You can use regular masking paper when you are just covering from light over spray. You are not only keeping paint from getting places but also keeping anything, DUST and DIRT, from blowing out onto your wet paint.
9) Get it into position where you plan to paint it.
10) blow it off again
11) wipe it down with grease and wax remover. Use lint free paper towels. I use Bounty, they tend to have very low lent and are as expensive as dedicated paint towels. I usually tear off 2-3 sections and fold it in half. I spray the g&w remover on the panel, just enough to cover, dont flood it. Then I wipe if off really good, then flip it over to do a final wipe. Move to the next panel. If you have cleaned it properly to this point, you are basically finalizing it and getting rid of finger and hand prints.
12) blow it off again, making sure you rub your hand across the panel, rubber gloves, as you blow it off. this helps knock any lint off as the air blows it away.
13) ready to apply paint