So been slowly DIY restoring the paint on my 540. Originally when I got the car, it was sitting infront of a machine shop for 2-3 years. Had a green tinged overspray thick on the car, the trunk and spoilers clear coat popped. I first started polishing process but soon perfection got into my head and soon I started painting.
So this was the process
1. Clay bar the entire car (I used the meguires yellow)
2. Chemical guys v32 cutting compound, applied by a Dual action rotary with a yellow cutting pad. (most aggressive possible). Got rid of alot of scartches and most of the swirl scratches. Follow it up with
3. v36 or v38 with a orange cutting pad (to bring out the depth and get rid of lighter swirls)
4. Finish it with a wax. I am almost done and planning on trying chemical guys jet seal and then applying black wax.
For the trunk and spoilers...the clear coat popped so they needed to be repainted. I also repaired and painted my ACS bumper lip since it was cracked. This is where I and most others would get anxiety of attempting to do for the first time. But basically:
1. Sand to basecoat using whatever grit. I used a rotary with 400 mostly. 120 grit by hand for the trunk because that clear coat layer was so hard. Finished with 600 grit. I don't have any pictures of this, but basically the goal is to get down through the clear coat, I found it fine to put primer on old base coat, although inevitably you'll be prime ring on the 2 or 3 old layers of base coat, the original primer, and maybe some bare metal.
2. Put down layers of primer. First 2 layers is very light and you should still be able to see the different layers underneath. layers 3 and 4 that are thicker and have that 'wet' look, until you can't or barely see the original different base coat layers. Primer you can make mistakes because you'll wet sand it with 1000 grit (very important because it reduces your work load later on with dealing with 'orange peel)'
2. Put down your basecoat. Jet black for my car is code 668 and is 25 bucks a can. Used 3 full cans for the spoilers trunk and lip. Put down 2 light coats and a third coat thick so it has a wet look, but not too thick or it'll run and you will have to re sand with 1000 grit and restart this step.
3. Clear coat time. I used about 2 acrylic cans total. 2-3 very light layers, followed by a thick wet look layer and finally a very thick layer. Very as in the you can see murky whiteness. Don't worry when the clear coat hardens that murkiness will be gone.
4. This is the most important step for a perfect paint job. No matter how well you painted the basecoat and clear coat, it will have orange peel. Even factory painted cars get this. So. To get that mirror finish reflection and feel you need to wetsand it. I used 2500 grit paper and sanded everything down until it was all matte looking. All the shiny or high spots you see when you first begin, all that has to sanded down so everything is a dull matte.
Right side is 2500 wet sanded, Left side is final layer of clear.
Notice in the picture the shiny or high spots
5. Number 5 is basically the first steps of polishing minus the claybar. V32 with yellow pad, followed up by v36 or v38 orange pad and wax.
Left side is 2500 grit sanded, right side is polish.
Right side is polished, left side is final layer of clear
Cost -
75 - 3x25 for jet black paint
20 - 2x10 clear coat
20 - sand papers
300 - dual action torqx rotary with cutting pads, v32 v34 v36 v38 polishes, carnauba wax, micro fiber towels.
lots of time.
Tips:
- I used chemical guys because someone here recommended them and I knew no other detailing shop. Its just off of dixie and 401. Im sure there are other cheaper brands that do the job just as well. Their youtube channel and the fact they do alot of work on bmw paint was helpful. You need to learn polishing technique and what pads and polishes to combine with.
-Microfiber towels, lots of clean ones.
-Spray can perpendicular to the surface when painting to minimize runs and orange peel.
-30 minutes between prime coats and basecoats
-10 minutes between light clear coats, 30 minutes between heavy coats
- Dont be afraid to 2500 sand between your prime coats or even your first and 2nd basecoats.
-Let your sandpaper 1000 and 2500 soak for at least 30 minutes
-While wetsanding, if your unsure of the thickness of your clear coat, stop frequently, dry it, and focus only on areas that show high spots.
-Temperature and humidity play a factor so my time estimate is based on 15 Celsius and high humidity.
-When I did the trunk and spoiler, i only painted the top halfs. I masked off the bottom halves, which did create a hard line. Do not worry, wetsand 2500 that away.
-Paint before polishing. As much as masking prevents overspray, unless your masking the entire car you will get over spray somewhere and will need to claybar that off. So paint before polish always.
- Finally what I learned most importantly is that wet sanding is nothing to be afraid of. Clear coats are hard and thick. So if you have any scratches or orange peel you want gone. Take 2500 grit to your paint. You'll think you will be messing it up making the whole area a dull matte, but polish clears everything up to perfection.
- Patience. This takes hours upon hours upon hours upon hours.
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