color sanding instead of repainting

[hankgaines]

My 89 Carrera 3.2 (Silver) has what appears to be failing paint, at least on the clear coat.. It looks like someone took coarse sand paper to it and there are areas where the paint has minute cracks. Several paint shops I have taken it to say I need to repaint it. I have been told by some mechanics that there is a procedure to restore old paint jobs called color sanding, a very long and tedious procedure. I want to keep the original paint if possible. Has anyone restored an old paint job this way?

[KevinP73]

Your mechanics don't know what they're talking about. Color sanding WON'T do anything to help your failing paint. A refinish is the only thing that will help.

[GorillaFoot]

Metallic paints are typically clear coated in order to keep the metal flecks from rusting. If the clear coat is gone or cracked, there is no bringing it back with color sanding (aka wet sanding). Now, if it was a solid Guards red, black, white, etc, with no clear coat, most Porsche paint is thick enough for color sand and often, one can bring back the paint to a very, very high level. You are effectively removing dead paint and smoothing scratches with fine grit sand paper, then polishing the paint back to a luster.

So no, sadly, your paint is screwed. Needs a repaint.

[962porsche]

clear is not to stop the metallic flakes from rusting .
they are non ferrous metals just for metallic flakes .
for years the US auto maker never cleared there metallic and you did not see them rust .

clear has many purposes .
one reason is to protect the flakes . but not because they rust !

[Bob Kontak]

Originally Posted by KevinP73

Your mechanics don't know what they're talking about. Color sanding WON'T do anything to help your failing paint. A refinish is the only thing that will help.

Now hold on there just a little second. A few cracks in the paint and some heavy scratches per OP's words does not automatically indicate the death knell for an original paint job.

Would be nice to get some clear pics of surfaces so a collective judgement could be made. (er, then we defer to what 962 says )

Also, is it common for original paint to crack?

[962porsche]

thanks but I have not given my opinion simply because there are no photos .
on Kevin's behalf I under stand why he has said repaint and that 's simply because so many others have said the same thing to the owner as he stated .
my guess would be the same if shops were telling him that .
once top coats start to fail they will only keep doing so .
yes you can get more life out of them at times but even wet sanding a SS job to bring it back to life will only last a short time . then the more product (top coat ) you remove the less there is to protect the substrate and the faster the less mils of top coat will last making you have to polish more to get that good shin back . it turns into a dog chasing it's tail .

[KevinP73]

Originally Posted by 962porsche

thanks but I have not given my opinion simply because there are no photos .
on Kevin's behalf I under stand why he has said repaint and that 's simply because so many others have said the same thing to the owner as he stated .
my guess would be the same if shops were telling him that .
once top coats start to fail they will only keep doing so .
yes you can get more life out of them at times but even wet sanding a SS job to bring it back to life will only last a short time . then the more product (top coat ) you remove the less there is to protect the substrate and the faster the less mils of top coat will last making you have to polish more to get that good shin back . it turns into a dog chasing it's tail .

Thank you but I can speak on my own behalf. The only reason I said a refinish was necessary was, in my experience (Porsche focused since 1978, that's 36 years in body man years, plus I saw an episode of Overhaulin with Charley Hutton) once the paint starts to crack it's normally cracked the full depth of the clear. No amount of sanding is going to change that. Cracking is an indication of dried out paint, failed and peeling. There is no making it better no matter how many pictures of it you look at or what the collective judgment may be.
But I'll be objective. let's see some pics of the offending surface and see what the collective thinks.

[hankgaines]

Thanks for the feedback. I once got the advice that you should never ask barber if you need a haircut. I figured the same could be applied to a paint and body shop but it sounds like they are giving me the correct answer.

From a distance the car looks great. Thats the reason I was looking for another solution. Trying to keep the original paint plus save money. I will take some up close pictures and post them.

[962porsche]

hankgaines
once the clear starts to fail and you have what are called checks/checking and cracks in the top coat moisture will leach thru the checking and start to damage the substrate .
primers , sealers, base coats also called undercoats will not and do not hold out moisture .
every time the surface gets moisture on it the moisture is going right thru to the substrate .

once in a blue moon I have seen where a panel is just starting to check and yes you can give it a light sanding with some ultra fine paper and buff it to were it's real hard to see the checking .
it does not remove it all it does is kind of hide it for a short time . as the top coat will continue to fail .

once the top coat cracks , checks you have to remove it from the surface of the panel / panels .
you can not apply more product (primer and paint) over the top of it !

at times saving money means spending it . putting money into a investment like a Porsche will gain you more money in the long run .



Kevin I'm very sorry I in no way men't to step on your toes !

[KevinP73]

Originally Posted by hankgaines

Thanks for the feedback. I once got the advice that you should never ask barber if you need a haircut. I figured the same could be applied to a paint and body shop but it sounds like they are giving me the correct answer.

From a distance the car looks great. Thats the reason I was looking for another solution. Trying to keep the original paint plus save money. I will take some up close pictures and post them.

Funny, I (a bodyman) have always said that mechanics usually sell you more of what they need then what you may actually need. I guess it just goes to demonstrate the disparity between the trades.
Your best way to approach the issue of your failing paint, providing you don't already have a trusted body shop, is just what you did here. Post the question and then sift through the replies. You'll find that guys who are full of bull***** don't last long here. Good luck with paint problem.

[GorillaFoot]

I actually had a silver Honda Prelude professionally repainted with metal body panels that were clear coated and plastic bumpers that were not. I think the color was PPG Sebring Silver, but this was 15+ years ago, so I am not certain of the manufacturer.

Guess what? The paint on the plastic rusted! I'd have to remove it with clay prior to polishing or else I'd scratch to paint up (which I did). Unless you have a better explanation why plastic would rust, let's assume that at least SOME metallic paints are ferrous.

Never seen a metallic Porsche without a clear coat... Just saying.

[bpu699]

Originally Posted by 962porsche

hankgaines
once the clear starts to fail and you have what are called checks/checking and cracks in the top coat moisture will leach thru the checking and start to damage the substrate .
primers , sealers, base coats also called undercoats will not and do not hold out moisture .
every time the surface gets moisture on it the moisture is going right thru to the substrate .

once in a blue moon I have seen where a panel is just starting to check and yes you can give it a light sanding with some ultra fine paper and buff it to were it's real hard to see the checking .
it does not remove it all it does is kind of hide it for a short time . as the top coat will continue to fail .

once the top coat cracks , checks you have to remove it from the surface of the panel / panels .
you can not apply more product (primer and paint) over the top of it !

at times saving money means spending it . putting money into a investment like a Porsche will gain you more money in the long run .



Kevin I'm very sorry I in no way men't to step on your toes !

Can you expand on this? This has always confused me...

I know that high build primer isn't water proof. But I thought epoxy sealer/epoxy primer was?

Are we saying that ONLY the paint and clear are water proof?

Intuitively, anything with the work "epoxy" or"sealer" in it, I always assumed was waterproof...

Bo

[962porsche]

I don't know of any paint CO. that uses or used ferrous metals for flakes .
there are many reasons why they would not and no reason why they would .


epoxy or etch is also not water proof . many do have chromates that help to combat rust but they are in not way designed to hold out water or moisture .
there is also the fact they have nothing in them to fight UV rays and the primers will break down in no time .
top coats and only top coats is the protection that protects the substrate .