painting over old factory paint

General Discussion. Make yourself at home...read, ask and answer!



Non-Lurker
Posts: 5
Joined: Mon Sep 13, 2004 8:22 pm
PostPosted: Wed Sep 22, 2004 3:47 am
Thanks in advance, i have a lot of questions!

I have a 1994 car that has front and rear urethane bumpers. The car's paint and body are in decent shape, however the paint is heavily oxidized. There are a few minor spots where body work will be performed. I have a few questions as to the steps involved leading up to the base coat.

I intend to leave the majority of the factory paint on the car. The paint is adhereing well still. I am going to wetsand with 300-400 grit and feather / fill any holes or dents.


1. Do I need to use a sealer on the old paint after I wet sand but before I prime?

2. What is the correct sequence for this, would it be body work / sand /wetsand/ sealer / prime/ sand .../ prime / sealer?

3. Can I prime over factory paint AT ALL?

4. If priming over factory paint is possible, what grit of sandpaper should I work up to before sealer / primer.

5. For priming, I know I am going to have to use something with flex agent for the urethane bumpers. Would it be okay to felx prime the whole car?

6. I want to go PPG paints, what woudl you guys suggest for a primer and base / clear for a good job?

User avatar

Top Contributor
Posts: 1433
Joined: Mon Mar 29, 2004 2:02 am
Location: Hell
PostPosted: Wed Sep 22, 2004 6:59 pm
1. Nope, unless you went through to the substrate or need to cover something, protect from filler. If you're repainting white you might consider a sealer, sealer is also good idea over filler or repairs.

2. Bodywork, sand up to 220, sealer/surfacer, sand up to 400 wet, sealer if needed, topcoat. Or something like that.

3. Sure, sand it well with 400 first. You're relying on that paint now, remember.

4. Hit it with 400 on a block till no gloss is left.

5. No, that's not a good idea. You may not even need flex on the bumpers, flex is mostly used to allow the peice to be manhandled during installation, not years later when you get hung up on a stump.

6. I don't use PPG, but their omni line is cheap and oft recommended.



Non-Lurker
Posts: 5
Joined: Mon Sep 13, 2004 8:22 pm
PostPosted: Thu Sep 23, 2004 12:30 pm
1. I would like to clarify this question /answer. The majority of the old paint will remain on the car. There are , of course areas that are in need of minor body work.

Did you suggest sealing any area with body work BEFORE primer?? I had to sand down to metal in a few areas before filling. Also, a few areas on the front urethane bumper have been taken down to the bare surface.

Also, I have installed some new fiberglass front fenders. These came unpainted, bare but smooth surface. I already blocked them with 220 grit at this point. Should I seal these or do anything special to them?

I am mostly concerned about sealing the car at this point. I know one needs to seal after priming, but I wonder if there are instances where you should seal both before and after.

Also, what kind of PPG primer would be ideal for this car? Keep in mind I will be trying to fill tiny scratches and pinholes in the factory paint.

Body icing- I have noticed this seems to be a popular item. When and where should it be used?

Kind of off the topic on this next one..... Is there a way to OVER do a paintjob? I realize that prep work is 95% of the job, so I have often thought about the "ultimat" prep job. I know it will cost, but it's my car, i am bored and I have $$$ lol. I was thinking something like this for the ultimate prep job...... (not that I am gonna run right out and do it, just for discussion now)

1. Sand 120 - 220 grit
2. Sand 300- 400 grit
3. Seal
4. High build prime w/flex agent (entire car)
5. Sand 500 grit
6. "regular primer"
7. Wetsand 600 grit
8. regular primer again
9. Wetsand 600+
10 prime again if needed
11. Wetsand 600 again (if step 10 used)
12. Seal


Thanks

User avatar

Top Contributor
Posts: 1433
Joined: Mon Mar 29, 2004 2:02 am
Location: Hell
PostPosted: Thu Sep 23, 2004 3:55 pm
I would always cover any sand throughs with epoxy (seal it). I wouldn't necessarily seal any bodywork before surfacer, although if you have polyester resin or talc on it that sure couldn't hurt. Fiberglass doesn't need a sealer, personally I would hit it all with a single epoxy coat before surfacer, it's not that expensive and you'll have better adhesion plus extra insurance with the sealer even in areas it isn't necessary. You don't necessarily need sealer after primer either. Search the forum for relevant terms, I know I've participated in lots of threads discussing it at length.

I don't use PPG, ask your jobber about a good high build 2k from whatever line you're using. Or someone else might give you a better answer.

I think icing is just slang for mud? Bog? Filler? It should be used as little as possible, to fill minor shallow defects that primer can't take care of but don't need fiberglass or metalwork.

No such thing as too much prep time, the more you spend the better it'll look. I wouldn't use flex on the whole car, that's not smart. I don't know what "regular primer" is or why you need something on top of your high build surfacer. You only need to sand up to 400, go to 500 if you're anal but don't bother with 600. All that sanding and recoating is just a waste of time I think, but your surfacer on extra thick the first time, guide coat and sand down to the sealer if you have to in order to remove it all. THen a final couple coats of surfacer and another guide coat and that's plenty, more coats means the defects you're trying to remove are waaaay too deep and you need some bodywork.

Don't forget a LONG block in an X pattern and don't push down on it. Work smart not hard, reading these forums is WORK that'll give you a better paint job.



Settled In
Posts: 10
Joined: Mon Sep 27, 2004 5:25 pm
PostPosted: Mon Sep 27, 2004 5:30 pm
Hope you don't mind if I jump in here.

By the way, awesome site. I learned a ton in the first 10 minutes of reading.

I have almost the exact same situation as Probin but my car is an '83 and the paint is heavily oxidized. I too have the factory paint still on there and have welded in some patch panels and am on my final stages of the Bondo.

My question is, at what point do you decide that the factory paint is too far gone, and it is time to sand the whole vehicle down to metal, OR, just wet sand it with 400? Thanks for any advice you can give me.

User avatar

Top Contributor
Posts: 1433
Joined: Mon Mar 29, 2004 2:02 am
Location: Hell
PostPosted: Mon Sep 27, 2004 5:47 pm
For me that decision is real easy. I look at the paint, and if not's something I recognize as personally applying within the last 6 months then it gets stripped off. But really, you need to look at stuff like delamination (one layer peels). I'm doing a car right now that the clear pulled off the basecoat on the hood, so I would never trust the clear on any part of the car even through just the hood might be affected. If you see bubbles it indicates that rust has formed under the paint, and it's likely that there are other areas starting that aren't visible through the paint yet. You might be able to see slight cracking caused by old filler (knock or magnet check), in which case it's possible or likely theres more filler waiting to crack in a few years. Any defect in the paint needs to be examined, consider the whole thing and decide how long you'll bet the current paint will last, because the new paint is only going to last that long and no longer if you apply it overtop.



Settled In
Posts: 87
Joined: Sat Apr 17, 2004 3:24 am
Location: Mobile,AL
PostPosted: Tue Sep 28, 2004 8:01 pm
Lets get somthing strait on the Sealer part:

okay.. you DONT HAVE TO SEAL ANYTHING before primer.. sealr is used AFTER primer.. the main reason to use sealer is so that the paint will cover better.. if your painting a green car red.. you will be in the booth alday trying to cover the green with the red and the primer as well.. primer's soak up paint.. sealers DO NOT.. thats why they call them sealers! I seal everything unless its a blend panel,, if it got primered,, its getting sealed everytime..that way,, I can just pas over it with color a few times instead of passing over it one dozen times or more.. plus it helps for color match.. if you replace a door and it is black and the car is white,, use a white sealer,, becuase the black may bleed thru the white and throw the color off enough to make u upset.

User avatar

Top Contributor
Posts: 1433
Joined: Mon Mar 29, 2004 2:02 am
Location: Hell
PostPosted: Tue Sep 28, 2004 9:20 pm
No, lets get this straight: Everyone works differently and does what works for them.

The first coat I put on anything is epoxy primer-sealer. You don't seem to understand why sealing metal is done, it's not done for coverage, it's not done to prevent bleeding of filler. It improves adhesion and seals the substrate. I'd argue with you, but I'm hoping you'll do us both the favour of a little research so I don't have to.

Do you know what DTM means in DTM epoxy sealer? Doesn't seem to fit your theory of sealer only topcoating surfacer and filler does it?



Settled In
Posts: 87
Joined: Sat Apr 17, 2004 3:24 am
Location: Mobile,AL
PostPosted: Tue Sep 28, 2004 9:26 pm
DTM: Direct to metal

and yes.. u have a point on filler.. but I dont care to use it just in an area Im going to apply primer to.. atleast not first,, I prime,,then seal.. but for one..Im a painter.. not a body man, so there ya go...



Settled In
Posts: 87
Joined: Sat Apr 17, 2004 3:24 am
Location: Mobile,AL
PostPosted: Tue Sep 28, 2004 9:45 pm
and ofcourse.. it does provide extra adhesion.. I should have read the post further.. I was thinkin this person was wanting to apply sealer over factory paint then prime, then paint.. that would be kinda backwards..atleast to me.. if there is bare metal showing..thast diffrent.. but if I just use some 400 wet on factory paint.. me personaly..I wouldnt wanna seal it then prime the thing..
Next

Return to Body and Paint

Who is online

Users browsing this forum: Google Adsense [Bot], ScottB and 27 guests