I've never sanded down a car before so I was curious what are the do's and dont's. The 86 Camaro I just got was spray painted and it looks like total crap so I wanted to save as much money as I could and sand it down myself.

 

Doesn't really look unusual... its pretty normal for a car to take on a 'camo' look after its been sanded.

Though I will say it looks like a pretty rough sandpaper you are using... what grit is that? It looks pretty coarse. If you are stripping to bare steel, use a 40-80 grit, but if you only want to sand the existing paint/primer to basically paint over it, then use a 180 grit and a sandable primer (which you should sand lightly with 400 grit paper or a red scotch-brite pad before coloring, then don't sand the color at all before clear... just spray the color, then spray the clear as described in the paint's directions).

 

Removing spray paint is difficult. You'll go through lots of sandpaper. Sometimes a chemical strip is easier and faster.

This is what my fiberglass hood looked like after sanding it down.

 

So should I take it down to bare steel or just down enought to where it is smooth; before primer.

 

Depends how bad the spray paint is. There's more to it than just sanding. It depends what kind of finish you want on the car. On my hood, you can see where the high spots were and the low spots were filled with body putty. A good body shop can get the body smooth and straight a lot easier and faster than you can. If you don't know what you're doing, you can easily sand too hard and create a lot of low spots.

You always sand up in stages. 80-100 grit knocks down the heavy stuff but leaves a lot of scratches that need to be taken out. Then you go to around 220 grit. Even though it will feel smooth, it's still very rough. 320 then 400 is usually enough for a smooth body but you could even go to 600 after that.

Body work and paint are always expensive because it's so labor intensive. Trying to cut corners may end up costing you more money if they have to fix mistakes.

 

I'm curious, i'm guessing that you used some screws or rivets to attach it down to the hood while you set it in whatever you used to bond it and then coated that in bondo and sanded it all out...

What did you use to bond it and has it cracked? (I've seen a lot of work like that look good for a while and then suddenly crack, I did some similar work that eventually cracked, but the car was also driven through a split rail fence, so I'm not sure if it cracked because of how it was done or because of what it hit)

 

The trick to getting it to look right is to give the whole area a skim coat of something (filler, primer, filler and primer...) and then start with some fairly course paper (80 grit is fine once you have the general contour), and only go till you _just_ barely start seeing bare metal through the filler/primer, if it needs more sanding either your metal work needs to be better or it needs more primer or filler, if you keep sanding at that point you'll end up with the steel becoming a high spot and the filler a low spot and even if it feels dead smooth and perfect when you paint over it you will be able to see where you painted over steel vs filler.

 

looks like you're trying to do that with a DA... from the appearance of that surface in the pics it looks like it pretty much all needs to be removed, and if that's the case I'd say that you're wasting your time (it will work, but it will take way too long).

Either start with a chemical stripper (I've done it before, not fun, messy and pretty easy to cause a lot of problems by getting the stuff where you shouldn't have), or take a large rotary buffer (7-9" pad, usually variable speed below 3000rpm) and get a stack of 60 or 80 grit disks and matching backing plate. Don't concentrate on one place/keep moving, and don't use too high an rpm (think 1800 or so rpm) or you'll overheat and warp the sheetmetal. Be careful not to gouge the sheet metal either

Once you're basically down to bare metal, do your bodywork and mud/prime... go from there.

 

if it was painted with spray cans, make sure you get it all off or you will have problems. paint wiil seperate and it will look like the surface of the moon

 

Cowl is held down with pop rivets. It was then blended to the hood with bondo. The brown splotches is spot putty to fill pinholes or imperfections. It's been 2 years now and nothing has cracked.

The aeroscoop is simply bolted to the cowl with about 12 machine screws. I can remove it if I want and it would show the toilets poking through the cowl.

 

Stephen, that's good to know, I've seen so many things done like you have that have lived and then a few that seem to fall apart, but there's always been a "maybe it was _____" that really caused the cracking, it's good to get feedback about it. In my case the parts were originally bolted and bonded together with 2 part epoxy, the seams were filled with bondo glass for a little bit of extra structure, and finally cleaned up with bondo, but I wondered if the impact or possibly water infiltration caused the problem.

 

If the paint is properly adhered to the surface then not necessary.

Most stuff out of a spray can is either lacquer or enamel, and the worst thing about it in particular is that if it's an enamel it doesn't have the enamel hardener that was usually used with better automotive enamels, which is what gives them their UV resistance.

Usually if it's pealing or doing just about anything else it's user error, not a problem with the paint, you would have had the problem with the best quality automotive paint of the same type out of a spray gun if done the same.

WRT to cracking, shriveling, allegatoring... when painted over that is usually a solvent problem, either you painted over something that was already cracked or pealing that gave a place for the solvents to gather and cause the problem, or you painted over with an incompatible solvent. If you don't know/are not sure and can't test, your best bet is still completely removing it, or if that's not an option, a quick coat of sealer can save you a lot of frustration.

(yea, pros will tell you a lot of things, and I would argue that a lot of them are motivated by what makes them the most money (every profession has it's things trying to make it a black art to others so others don't think that any old monkey can do it), what's a hassle to them, and finally just not knowing for sure. You'd be surprised what you can do with a rattle can and a little knowledge/patience, OTOH, I wouldn't recommend it for anything but the smallest areas... and even then I've noticed that I've been using a detail HVLP gun more and more for little things)

 

We're scrapping a step van truck at work and I had to remove all the company decals today. In the past, they were using a heat gun. I've used this stuff before so I picked up a couple of cans. I had the whole truck de-decaled in less than an hour. Spray it on, wait about 10 minutes then use a razor blade to peal the paint and decals right off. If I had about a dozen cans, I could have had the whole truck stripped down to bare metal in a few hours without any sanding scratches. We weren't worried about the paint. Where the decals were, I repainted it with a roller

http://www.permatex.com/products/Aut...t_Stripper.htm

 

The first scoop I attached to a fiberglass hood about 9 years ago didn't do too well. There was a bad crack in the gelcoat at the front and it had at least one crack along the side. There was way too much bondo in the entire hood and it was very heavy. I found another factory fiberglass hood a few years later and bolted on a 6" cowl instead. That only lasted a couple of years as it was way too high. I finally went to the current design and I'm very happy the way it turned out. With the short cowl and aeroscoop, it's hard to tell there's a tunnel ram under the hood.

The only screw up I did was when I riveted the cowl on. The tunnel ram prevented me from closing the hood until the cowl was attached so that I could see where to cut the hole. When I bolted on the cowl, the back of the hood is a little bit wider on the passenger side. I never really noticed it until after everything was bondoed. I had to space the fender out so the hood wouldn't bind on the fender. There's now a misaligned gap between the passenger fender and the door.

As I've said in the past, I'm not making a show vehicle. Very few people would notice the excessive gap. I'm not taking the cowl off the hood now to reposition the hood and fender. Maybe when I install my fiberglass doors this winter, I'll correct the misalignment by positioning the door outwards a little more.

 

Hello from central Texas. I'm right down the road from you in Bastrop.

As stated above, the best way to get spray paint off is with chemical stripper and a razor blade. I stripped a fender to metal with that method in about 15 minutes. It had about 6 layers of paint on it.