Copyright ©PBMA - AutogeekOnline.net® All Rights Reserved
In the collector car hobby world, there’s a lot of interest in restoring and preserving original paint on classic and antique cars. Restoring the original paint maintains the overall originality of the complete car and adds to the value as long as the resulting finish is acceptable in appearance and represents how the vehicle would look for its age had the paint been properly maintained over the years.
Hard as it is to believe, people are still finding old cars in barns, storage buildings and garages across this great land and with the right products, techniques and a little knowledge of what to do and what not to do, it’s possible to restore a show room new finish to these time capsule treasures.
What to do
If preserving the original paint is important to you then the first thing you want to do is condition the paint before working on it. Most people just jump right in and start rubbing some type of abrasive compound over old, dry, fragile paint and this will remove a lot of paint quickly and possible remove too much. Instead, take the extra step of conditioning the paint and bring it back to life with product that's been around since cars and thus car paints have been around.
Below I will share the product and actually a technique that may restore your car's paint to your expectations without using any abrasives at all. In the car detailing world we're always talking about the idea of,
"Use the least aggressive product to get the job done"
In this article I'll show you at least one way to put that philosophy into practice.
What not to do
The first thing most people do when trying to restore an old, oxidized finish is reach for some rubbing compound and try to rub the dead, oxidized paint off the car. While this will work, it's the caveman approach because it's too aggressive, it will remove too much paint and because there's a better, safer approach that will provide a better chance at preserving as much of the original paint as possible which is the goal if you're trying to preserve the "originalness" of the car.
So if you're reading this and you have an old car out in the garage that has oxidized single stage paint, let me share with you a way of conditioning the paint in a non-abrasive way that will make your car's old, tired paint come back to life. Then you can either stop at that point if you like the results you're seeing and apply a coat of wax or I'll share with you how to machine polish the paint to squeeze out even a little more depth, shine and gloss.
The problems with restoring antique and original paint
- Single stage paints are prone to oxidation
- Single stage paints are thin
- Single stage paints are fragile
- Single stage paints are soft
Single Stage Paints are Prone to Oxidation
Antique and older, single stage paints are usually some type of lacquer or enamel and these paints are prone to oxidation when exposed to air and moisture over time.
Oxidation in simple terms is when the oxygen molecules in the air act to remove electrons from the paint resin. In other words the paint deteriorates by coming apart or disintegrating.
This usually shows up as a chalky whitish looking color on the surface of the paint even if the paint was originally some other color besides white. Just to note, white paint will oxidize too but because it’s the same color as the chalky white oxidization you have to look carefully to see it. Oxidized white paint can just look dull when it in fact is oxidized.
If the oxidation isn't too extreme it will merely be a topical problem that is easily fixed by simply abrading the surface to remove the oxidized or dead paint off the surface, which will expose a fresh base which you can then polish to a high gloss.
Single Stage Paint = Easy to Restore
Here's an example of mild oxidation on a yellow single stage enamel paint on a 1960 Ford Ranchero, on which I restored the paint a few years ago...
Here's what the paint looks like after the oxidation was removed and the paint was polished to a high gloss.
Single Stage Metallic Paint = Difficult to Restore
Single stage, non-metallic paints like the above paint on the Ranchero are actually very easy to fix because the problem is for the most part just topical, that is the problem is just on the surface. All you have to do is remove the dead paint off the surface and if there's enough paint left then it's just a matter of polishing what's left to a high gloss. The most difficult paints to restore are single stage metallic paints.
The reason single stage metallic paints are the most difficult to restore is because not only does the paint itself oxidize, that is the resin used as the binder, (generally some type of seed oil like Flaxseed oil or Cottonseed oil), but also the aluminum flakes embodied inside the paint oxidize. This is where the problem lies.
It's a problem because the entire exterior surface of each individual aluminum flake oxidizes over time but you and I can only work on the surface of the paint and thus we can only work on the portion of the flake that is exposed at the surface level. Any portion of each aluminum flake that is below the surface and is surrounded by paint cannot be cleaned or polished so there's no way to remove the oxidation on the portions of the flakes inside the paint.
Oxidized Aluminum Turns Black
With metallic single stage paints, oxidation can show up as a darkening effect on medium to light colored paints because the aluminum metal flakes embodied inside the paint will stain or discolor the paint with a grayish black color.
If you’ve ever polished uncoated aluminum then you’ve seen this grayish black color coming off the aluminum and onto your polishing cloth as you work a metal polish over it. This same type of oxidation is taking place to the aluminum flake inside the paint.
Polishing Uncoated Aluminum
Oxidized Aluminum Comes Off Black
Wolfgang MetallWerk™ Aluminum Polishing System
In the same way you see the black residue coming off the aluminum wheel onto the piece of white cotton terry cloth material above, when working on metallic single stage paints you will see black residue coming off the paint and onto you applicator pads, buffing pads and wiping towels.
This darkening effect can take place even at the same time the surface of the paint itself is turning chalky white. This is because you have two different substances oxidizing, both the paint and the aluminum flake, which both are oxidizing at the same time. The paint oxidizes white and the aluminum flake oxidizes black.
Besides the oxidation issue, here are some other problems associated with restoring antique and/or old single stage paints...
Single Stage Paints are Thin
Factory paint is thin to start with, now add to this that over the years other people may have worked on the paint in some fashion and abraded some of the coating off, so not only is old factory paint thin to start with, it can potentially be thinner than when it was first sprayed just due to the fact that other people have worked on the paint before you.
This is another reason you need proceed with caution and always follow the best practice of,
"Use the least aggressive product to get the job done"
(Note I used the word aggressive, not the word abrasive, there's a difference)
The challenge when paint is thin is how to restore the paint by abrading it without destroying it at the same time because there's just not a lot film-build to work with. Words cannot describe the heart sinking feeling an owner must experience when they discover they’ve polished through the topcoat of paint and exposed primer or even worse… shiny metal!
Single Stage Paints are Fragile
Single stage paints are a lot more porous or permeable than today's modern basecoat/clearcoat paints. Liquids can penetrate more easily into them and the oils the paints are made with will more easily leach-out and as a result the paint will dry-out over time.
When the paint dries out, besides having a chalky appearance due to oxidation, it will also become fragile and weak. It will be dramatically more susceptible to attack by any corrosive or destructive liquid introduced to the surface, for example brake fluid.
Modern clear coat paints are non-porous or impermeable, that is the resin structure is more dense and oftentimes harder. Liquids cannot easily penetrate into the resin, nor will the resin, deteriorate as easily or quickly like single stage paint.
Single stage paints are soft
Generally speaking, single stage paints are soft, at least soft when compared to modern basecoat/clearcoat paints.
The exception to this rule, (single stage paints are soft), is when it comes to single stage white paints and this is because the type of pigment used to add color to a single stage paint can and will affect the hardness of the paint. In the case of single stage white paint, the pigment type is Titanium Dioxide Powder. Titanium Dioxide is a very hard substance in and of itself and when mixed with a paint resin it modifies the workability of the paint making it a harder coating than the resin would have been with no Titanium Dioxide added to it. Conversely, single stage black paint is the softest paint there is to work on because the pigment used to make black paint is Carbon Black, which is basically similar to the soot that builds up inside the lid of an outdoor barbecue or inside your fireplace chimney. Next time you’re around either a barbecue or a chiming, rub your finger against the lid or inner brick wall and you’ll remove a very soft, powdery substance; this is a type of Carbon Black.
Suffice to say, most single stage lacquers and enamels are soft to start with because of the raw materials used to make them, (seed oils), except if they are white. Over time as they dry out, they become softer and it’s important to know this because using anything sharp or abrasive like an archaic rubbing compound will remove a lot of paint quickly.
Restoring Single Stage Paint: Part 1
The secret to removing oxidation and restoring a show car finish to antique single stage paints.
Restoring Single Stage Paint: Part 2
Choosing the right polish.
Restoring Single Stage Paint: Part 3
Cleaning your paint.
Restoring Single Stage Paint: Part 4
Removing oxidation without abrasives.
Restoring Single Stage Paint: Part 5
Sealing the paint.
Restoring Single Stage Paint: Part 6
The first polishing steps.
Restoring Single Stage Paint: Part 7
The final polishing steps.