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WCN621 05-08-2012 06:33 AM

Refining poor paint finish areas and touch up '84 911
First post after purchasing an '84 911(also 1st 911 - :D). Bought car as a "driver", but as always, never satisfied with "as is". Even with a number of mini projects to do, the paint condition is bugging me.

Two issues:
1) One of PO's had a partial respray and is ok, but in areas like noted in photo, there is a not a complete coverage on respray and have distinct paint lines showing. How can I "smooth" these to improve transition of paint? I am quite a ways from needing total respray, so this is for now (and my satisfaction on apprearance).

2) There's a couple of areas where there is no paint (roof surface rain channels above doors). What would be be best (and how) to protect this surface? I'm not in financial position to have this repainted at shop (as I have a few more things to do to car), but want it to still look "factory" and protect the finish.

3) OK, so there's another... ;) Car was stored outside under a cover for a few years by a PO. I am sure that's the factor for paint condition. Have read through forums with all kinds of advice, but haven't found answers to above or what's best to bring finish back (also considering issues above). Recommended steps to restore and improve paint and finish? Thanks all!!!

962porsche 05-08-2012 12:12 PM

this is common on repaints when things are not removed and then they don't prep sand up to the edges . as for around the wiper posts i would pull the wipers and rubber gaskets and just respray the cowl panel . as for the roof you could repair that in two ways . you could do a tuch up . of because it's the roof and rain gutters i would opt to just repaint that as well .
the best way would be to remove the front and rear glass but it is not a must . there are ways to use what is called lifting tape or some twine under the gaskets .
the down side is that if that part of the cars is pealing then don't be shocked if you start to see more pealing in other areas down the road .
also because it is pealing from the looks of bad prep work it makes me think how the rest of the panel was prepped as well . if it was just done bad the finish may not feather out and that would lead to sanding off the finish that they sprayed . you would not have to strip it down to bare metal most of the time just the last repaint . but again thats a if ?

strath44 05-08-2012 02:35 PM

it looks like a lack of primer / undercoat at the rain gutter - primers probably been shot from floor height and not covered the lower parts of the gutter properly because of the angle!? Good thing is that you could try masking the gutters off sanding them and painting them, if you don't creep up onto the roofline the gutters will hide the paint line. Opening a total can of worms in a way you are almost better touching up with a small brush a rustoleum till such times that you can do it properly - seriously consider how much time you put in, you could sand the roof and paint it ok then the wings start peeling!

strath44 05-08-2012 02:39 PM

ps sorry that sound really negative congrats on the 911 it will bring you countless joy, best plan just now is give it a good clean and buff then get a project list on the go! A machine polish can breath a bit of life into a poor / tired paint finish!

962porsche 05-09-2012 05:36 AM

primers do nothing to get adhesion . that is not what a primer is for . that looks like it is pealing from lack of proper sanding . the bottom line is if you don't sand it the new finish will not stick .
as for tring to spot in the areas it's not really worth it there just to big and you will spend more time trying to do spot repairs than just to feather every thing out prime and then repaint it .
there is nothing to R and I on the roof it's self and you will have to R and I the wipers any way so at that point it will just be faster and easier to feather the areas back and then just repaint the hole panel .
the thing is because it is paeling it will not stop water and dirt will ceep getting under the edge of were it is pealing and ceep lifting up little areas at a time untill it peals to were they really did do some sanding .
you could tuch it up to just get some color on it and to help with crap from getting under the edge but it's not a cure .

strath44 05-09-2012 08:46 AM

"primers do nothing to get adhesion " hmm yes and no they won't do anything to get adhesion if the metal / base is badly prepped or contaminated, but the one of the main purposes of a primer is to give an adhesion of which a colour coat doesn't contain the same properties!

962porsche 05-10-2012 05:39 AM


Originally Posted by strath44 (Post 6737674)
"primers do nothing to get adhesion " hmm yes and no they won't do anything to get adhesion if the metal / base is badly prepped or contaminated, but the one of the main purposes of a primer is to give an adhesion of which a colour coat doesn't contain the same properties!

primers are not made for gaining addhesion at all it's a surfacer to give you a flat even surface for the top coats to lay over the top of so they will not srink into the substraight . that is all a primer is for . it's in no way a adhesion promoter ! it will not add one bit to getting a top coat to stick any better .
that is why you only have to prime over a repair area and not a hole panel .
say your doing a repair on a door you prime the repair area and then spray your color over the repair area and walk the color out twice as far as the repair area was . then you clear the hole door . you in no way have to prime the hole door to have the top coats to stick to the door it's self .
now to get the top coats to bite into the primer and old substraight all you have to do is sand the hole door and every bit of it with the proper grit sand paper and panel prep scuff product like sem's # 38338 .
if you look at the photos you may see it does look like there is a primer or a sealer that could have been used ? in the rain channel it looks like it has a much darker color under were the top coat is pealing . also if you look around the wiper post you will see what it looks like a very thin gray line that also tell me there could be a primer or sealer that was used when the car was repainted .
the simple fact is if it's not sanded and sanded right with the proper grits of paper and scuff prep then nothing you put over the top will ever stick .

now the black under the top coat on the rain channel could have been a seam sealer that was not primed over that may should have been . and the top coat is just lifting off that because it needed a sealer or primer ?

strath44 05-10-2012 10:05 AM

hi i'm sorry unless there is a transatlantic difference in what a primer is then no, primer 100% adds adhesion as part of its properties the other are some of which you mention.

WCN621 09-21-2012 06:17 AM

More questions, related issue. Unfortunately car is stored currently at distance (temporary), so I haven't been able to address paint issues. Good friend emailed me photos of another 911 same year, same grand prix white ('84) that had original paint and the finish was outstanding. How best to bring back the overall paint?

Recommendation was to overall wet sand starting w/1500 then move up. Not sure if it has Clearcoat, what year did Porsche start applying Clearcoat? If so, what should I do to improve just clear coat. I've done wet sanding when a kid w/my dad on cars, but has been 35+ years, so a little uncomfortable until I have more information to do so on my "girl". Thanks.

Zeke 09-22-2012 01:27 PM

I've had 962 come down on me before. He can be as opinionated as anyone can be on the Net. Just because one guy says it's so doesn't make it so.

Regarding post #7 it sounds like he's talking about sealer in one part and sanding primer in the other part. When he says primer doesn't add more adhesion, he's technically correct. It doesn't make it any worse either. So as a sentence, it's correct. As a thought, it's incomplete.

You would not want to paint a car that was well prepped over part primer and part prepped original finish w/o a coat of sealer over the panel to be sprayed. If blending the base coat out into the middle of a panel, you might want to use a clear sealer over the whole or most of the panel first. Base coat comes next if using a 2 stage system. Then clear coat the whole panel well past the blend line if there are no stopping points (like a rear quarter finish on a 911).

One product to consider is DuPont™ 222S™ Mid-Coat Adhesion Promoter. This works really good in hard to prep areas such as door jambs. So there you have it. There is something that helps adhesion. But it's not really a primer or sealer. Each has its own usage.

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