Sanding down to original paint

[Edwin Ek]

The previous owner of my car told me that his father and he painted it in their driveway. The paint job is of so-so quality (no surprise that) and in so-so condition currently. So I am not risking much with an experiment.

What's visible in some places suggests it is original paint underneath. Surely the driveway painters didn't strip the car to bare metal. They did the job in the early 1980's.

What is involved with sanding down to the underlying paint? How long does it take? Is this a fiasco in the making? I remember that Willhoit did this for an America Roadster he worked on. Is there a good way to confirm that it is original paint before going through the effort?

I would be happy with a result that is pretty far from perfect ...

[Martin Benade]

Usually it is repainted because the original paint was not good. It is not easy to remove only the newer paint, but it may be possible. No harm in trying, if you have a lot of time and patience.

[Greg Scallon]

Edwin,
Do some searches on The Samba. Lots of folks over there are stripping off newer paint jobs to pull back their original paint. There are all kinds of tricks and options to learn about. Good luck!
-Greg

[Mickey Murfee]

Edwin:

I sanded 7-8 coats of paint off our '56 Speedster with a Makita rotary sander. The RPM of the machine was about 1500 and the sandpaper was a 80 grit. It slowly took off the old paint, did not indent the metal or the leaded areas. Overall I was very pleased with the results. It took 6-8 hours total to get to bare metal. As one could imagine there was a lot of dust.

Mickey Murfee

[Drew Ogden]

Chemicals are your friend, sanding is not always the best option.... The type of chemical is dependent on the type of paint that you are removing. Plastic scrapers and wet rags to stop the chemical stripping process are a must.

If it is an important car with decent paint, maybe best to have an experienced person do it. I have always paid people for this type of work, some experience makes for a much better finished product.

Good luck!

[Emil Wojcik]

Edwin's asking about sanding down to the original paint, not down to metal. No experience with it myself.

[Dan Kalinski]

First hand knowledge here as our '59A was painted in the driveway many years ago by the PO. You will need sanding blocks of various shapes and sizes along with wet dry paper from 600 to 1200 or higher.

Unadvisable to use your hands behind the sand paper as using this method will leave ridges, hence the need for sanding blocks. All available at your auto paint supply store.

There are lots of YouTube videos. Watch a few and choose a method.

My sand process is to vary the direction when sanding. That is to say, complete the panel you are working on in a direction (all the same) then vary the angle by 25 or some other random degree. Complete this step then make an assessment and move on to the next finer grit, rinse-repeat. As you go to more finer grits, change out the water/soap mix and make sure there is no cross contamination with the micro fibers used on each successive grit. Same for the polishing process.

Used warm water with dishwashing soap for the lubricant and to flush the paint/paper. If doing this process on untreated concrete floor, the paint runoff may well stain the concrete. Suggest some sort of barrier is placed to catch all the runoff.

3M has a three step process for polishing which is color coordinated with orbital pads. A good friend swears by this process. My process is a 4 step and all the pads and different polishing media was purchased at Griot's Garage. Buy a nice orbital polisher. Don't go cheap here as you will develop a relationship with this instrument so make it a good one.

How long does it take........ Up to you and the quality desired. Patience Makes The Polisher.

Have fun. A rewarding and satisfying project.

[John Brooks]

Dan's coupe looks great. It takes a while.

I started with 400 wet, but went to a Dual action dry 400 grit to start chasing fish eyes in the top coat. Then 400-600 wet with long blocks. Squirt bottle with soap and hot water. Get a good sander, oil free pneumatic motor.

[Martin Benade]

John, that's a new paint job? 400 is too coarse for him to safely uncover an original paint layer. 400 or 600 is what we used to use on fresh lacquer 25 years ago, now most people use 1500 or so on fresh paint.

[John Brooks]

Martin

We are working on a single stage base coat. Right now it's get it smooth.
We will progress through the higher grits and the through the polishes before its complete. I had some kind of contamination, probably water, although had inline descant dryers in the hoses. But what can I say, this one will look like lacquer when we are done.

Dan's 59 coupe is beautiful, including some old plastic repairs. If you go high enough on the grit and polishing compound it will shine.

[Martin Benade]

You are correct that finer grits will eventually get it to shine nicely, but there is a real chance of going through the paint, especially the original paint which is not very thick. I hope your green paint is nice and thick so you have room to get it smooth and beautiful.

[Emil Wojcik]

Choosing the correct grit depends on the surface. If the paint needs to be smoothed, e.g., removing orange peal, it will require a courser grit than if just polishing an already perfectly smooth surface. When used on orange peal, if the paper is too fine, you won't remove the peal, you will only polish it.

So, depending on the surface, both of you are correct.

[Chuck House]

I've done this before. Use chemicals!! The original paint is quite thin compared to re-paints, however it is baked on and is more difficult to remove with stripper than a driveway paint job. Use the generic paint stripper you get from Home Depot or Loews. Don't use the better aircraft stripper as it is more aggressive. Do small sections at a time and scrape off the top paint with a hard plastic putty knife as soon as it bubbles. The guys who last painted it may have sanded through the original paint in areas or made repairs so your end result may or may not be acceptable to you. However you never know, you may get lucky.

[Adam Wright]

I've done this before. Use chemicals!! The original paint is quite thin compared to re-paints, however it is baked on and is more difficult to remove with stripper than a driveway paint job. Use the generic paint stripper you get from Home Depot or Loews. Don't use the better aircraft stripper as it is more aggressive. Do small sections at a time and scrape off the top paint with a hard plastic putty knife as soon as it bubbles. The guys who last painted it may have sanded through the original paint in areas or made repairs so your end result may or may not be acceptable to you. However you never know, you may get lucky.

Chuck is right, the aircraft stripper is faster but can really go deep fast. This works well if you're going for metal, but not for what you're trying to do.

[Harlan Halsey]

I take it that this is motivated by the originality baloney that seems to have gripped a part of the 356 community. A car is original only when the factory ships it. After that it is a deteriorating car. It will never be original again, even if it is returned to the factory for refurbishment. Most 356s were driven a lot. And those very few that were stored deteriorated too. In New England, where I first bought my first Porsche, road salt in the winter and fluctuating humidity all year took a rapid toll. A very well cared for car might look good for 5 years, but the inside of the rocker panels were shot. It was hazardous to use the jack. In California where I now live, cars deteriorate much more slowly. But they still deteriorate, the rubber oxidizes, the chrome dulls and so on.

But an original look car is easy, if expensive, either in time or money. Since that's all you are going to get, why not shoot for that? Strip it to bare metal, you will learn just what the condition of the sheet metal is and maybe something interesting. Such as did Porsche use plastic filler or only lead and where. (My Convertible D, 85519, has 18 a foot high with a lead brush on the tail. Must have been a little confusion at the factory.) Or, if there is enough of the paint still good, sand it down and use it as the base for the new paint. I did that on my 63 SC. That was ten years ago and today I'm not sure which panels were stripped to bare metal and which were not. It all looks pretty "original". Either approach makes more sense to me than what you are proposing.