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Discussion Starter #1 (Edited)
A question I frequently see is, what sort of paint system should I use? Base/Clear? Base only? Urethane? I will let you in on a little secret, it really doesn't matter, within reason. What makes great paint look great has almost nothing to do with the paint but rather the panel preparation prior to the paint, and the sanding and polishing after its painted.

While the terminology is confusing -- Single Stage, Two Stage, Catalyzed, Urethane, Acrylic, Enamel, Lacquer, POR15, etc... the choices are quite simple. In modern paint there really is only a couple choices you need to make. I will explain, perhaps with too much detail.

I will not be offended if you jump to the end to read the bottom line.

The Nitty Gritty

Paint comes in four main flavors: Nitrocellulose Lacquer, Urethanes, Acrylic, and Epoxy. Most paints are available either as single or dual stage and catalyzed or not. Note, frequently the word enamel will follow the paint type (ie Acrylic Enamel), this is almost meaningless. Enamel is defined as a paint that dries to a hard glossy finish, hardly helpfull!

Base/Clear Confusion
Some paints are available as either single or dual(double) stage paint. A single stage paint is a paint where the top coat is tinted. Dual stage paint has its pigment in the base coat, and is covered with a clear coat of paint. Not surpizingly, dual stage paint is also referred to as base/clear. In most circumstances, people are referring to Urethanes paints when talking about base/clear.

In dual stage urethane paint systems, a basecoat is applied, This coat is generally not shiny, and may or may not contain metallic or pearl flakes. It is applied extremely thin (1-3mils) and topcoated (6-12 mils) before it has dried with a high-gloss, clear urethane. One looks through the clear and sees the color in the basecoat. When done properly, it is has a high luster and is very durable. If you are using metallics or pearls, it is the only system.

Single stage urethane is simply dual stage paint where the clearcoat has been tinted and the basecoat has not been applied. Rather than using a clear coat, the clear is tinted with solid pigments. The paint is virtually identical other than being opaque rather than clear. In older systems, the single stage was not as vibrant as the dual stage, but that is no longer the case. Single stage paint is slightly less expensive than dual stage because of the need for less material.

One of the main advantages of dual stage is that it is easily repaired by a body shop. After a body repair, you can spot in a small area with more color, mist the panel with color, and then reclear the area. The reclearing makes it difficult to detect the seem between old paint and new paint, as the seam is clear. Repairing single stage is the same, but it is easier to see the seam between the old paint and the new paint, particularly if the color is even a tiny bit off. For this reason, and this reason alone, I prefer dual stage paint.

Most bodyshops only have dual stage paint mixing systems on site. For this reason and the ease of repair, most bodyshops prefer dual stage paint.

Catalysis
Catalyzed paints use a chemical reaction to cure, Non-Catalyzed paints air dry. Catalyzed paints are more expensive and more durable than non-catalyzed paints. Catalyzed paint need a base paint, a hardner, and a reducer (thinner) and must be mixed just prior to using. Non-Catalyzed paints do not require mixing, and will remain liquid a long time if not exposed to air. All spray paints are Non-Catalyzed. All body shops use catalyzed paints.

Etching or Direct to Metal
Some paints are direct to metal, some are not and require a primer. DTM paints have a small amount of acid in them to etch the metal they are applied to form a chemical bond to the underlying metal. Make sure you know which you have. If you spray a non DTM paint directly on metal, it will flake off, and conversely some DTM paints will blister most primers. Self etching and DTM are the same thing.

Paint Brands and Lines
Every paint brand (Sherwin Williams, PPG, Glasurit, etc) creates excellent paint nowadays. The chemistry is well known, and all major Urethanes are excellent. There are differences in approach, and how easy they are to spray, and mix, and other things the painter needs to worry about. But, the car owner will probably never be able to tell the difference from one paint brand to another.

Inside the brands, there are paint lines. Sherwin has Sherwin Williams line, the Dimension Line, and the Western Refinisher's Line. The chemistry of the paints is pretty much the same, but not all the colors are.

For example: You cannot buy Ferrari Rosso Corso in anything but the most expensive Sherwin Williams line. The Western line only has a few dozen colors in total you can buy. If you don't care whether you have the exact color match, you can save a mint choosing a fleet paint color. Can you tell the difference between Rosso Corso (Sherwin only ~$450/gallon), Miata Red (Sherwin ~$400/gallon, Dimension ~$200/gallon) and fleet red (~$400/gallon, Dimension ~$200/gallon, Western ~$100/gallon)?

Types of paint

Nitrocellulose Lacquer:
The old school finish, frequently referred to as simply "Lacquer". It is a pigmented cellose-base in a disolved in mixture of solvent. In other words, color (pigment) suspended in lacquer thinner. This stuff is gorgeous, super cheap, easy to spray, fast drying, short lasting, labor intensive, and illegal almost everywhere. People would spray on coat after coat of this stuff, hand rubbing between coats, to build up a deep luscious color (this is where the still persistent myth of multiple coats comes from). Unfortunately, this paint did not age well and needed to stay out of the sun and elements to remain colorful. Since you probably can't buy this stuff, my advice is not really relevant, but I would not use this paint in favor of the new paints.

Urethane:
All modern cars are using Urethanes. These are crystalline compounds that are either tinted or clear. They are quite hard and flexible compared to other paints and stand up to the elements exceptionally well. They are wildly expensive ($200 to $500 a gallon) and difficult to apply well, but last a long time. In most places, this is the only type of paint you will be able to get for your car, and really the only one worth considering. They are all catalyzed and available a single stage or dual stage. They are not direct to metal and require a primer.

Acrylic:
Acryclic paint is made out of acrylic resin. It is cheap, easy to apply, and relatively long lasting. It is not as durable as urethane, much more durable than nitrocellulose lacquer, and suitable for many applications. It does not have the luster of urethane, either. It is available in catalyzed and non catalyzed version. They can be either Direct To Metal or not.

Almost all spray paints are Acrylic as well as most of Eastwood's paints.

I use acrylic paint a lot in restoration work. I use it on almost all non exterior surfaces (air cleaners, shocks, pulleys, interior trim) and some exterior ones (wheels for example). It is cheap to get color matched, holds up well, and sprays well out of any spray gun, including Preval Sprayers (little spraycans with jars so you can mix your own paint http://www.prevalspraygun.com/). I almost always use a catalyzed, non-direct-to-metal version since it is more durable. But, occasionally I use SEM's Trim Black spray paints as well. They are direct to metal, inexpensive, and durable.

Epoxy:
Most chassis paints and rust converters (POR15) are an epoxy base. Epoxy paints are extremely strong and durable, low gloss, easy to apply and moderately expensive. They come in Catalzyed and non Catalyzed versions. I use them on chassis components and places that have some surface rust I cannot remove for whatever reason.

A note on Rust Converters
Rust converters chemically bond to iron oxide (rust) making a new compound that is extremely hard, durable, and waterproof and airtight. They rely on the iron oxide for their adhesion. They do not prevent rust, they only bind to rust.

Self-etching primers etch themselves into steel, forming a waterproof airtight barrier, but they do not bite into iron oxide.

What does this mean? If you cannot remove all rust from a piece of metal, use POR15 by all means. But if you have a rust free piece of steel, do not use POR15 on it, use an etching primer, you will get a stronger, more durable finish for less money that way.

The bottom line
If you are taking your car to a shop to have its exterior painted, besides color choice, you really have to worry about the choice between single stage or dual stage (base/clear). Both are excellent choices. Single stage is probably, but not necessarily a little bit cheaper than dual stage, but harder to repair invisibly by a professional or a skilled amateur. When done well, you will not be able to tell the difference in material choice by looking at it.

Generally, I would let the shop pick the materials they want to use. They may have a better deal from one vendor than another or just like the way a paint flows out of their favorite paint gun (don't even get me started on paint guns, they probably have more to do with the final finish then the finish!) and get better results with that. Chose your bodyman carefully and trust them.

Most people confuse the quality of bodywork with the quality of the paint. Look at the shops previous work. Get references. Really. Make sure the paint holds up a year or two after it left the shop. If it didn't it wasn't the paint, it was the painter. There is a tremendous amount of skill in body and paint work. As in most things in life, the people make the difference, not the chemicals.

Good Luck,

Mike
1974 Alfa Spider Daily Driver
1965 Jaguar E-Type
1977 Ferrari 308 GTB
1965 Plymouth Sport Fury with a 426 wedge
 

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Thanks Mike,

This sort of info is pure gold to us amatures.

Just one minor point,

This:
Vantaaj said:
One of the main advantages of dual stage is that it is easily repaired by a body shop. After a body repair, you can spot in a small area with more color, mist the panel with color, and then reclear the area. The reclearing makes it difficult to detect the seem between old paint and new paint, as the seam is clear. Repairing single stage is the same, but it is easier to see the seam between the old paint and the new paint, particularly if the color is even a tiny bit off. For this reason, and this reason alone, I prefer dual stage paint.
Seems to contradict this:
Vantaaj said:
Both are excellent choices. Single stage is probably, but not necessarily a little bit cheaper than dual stage, but easier to repair invisibly by a professional or a skilled amateur.

Now, does anybody have any good tips about base/clear application?
 

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It should be pointed out, that the catalyst used in most catalysed (2 pack) paints is toxic, they are isocyanates, and are ideally sprayed in a booth with the painter wearing full protective clothing ( this stuff can be absorbed by your skin) with external air supply to their mask.

If you were to spray it at home, make sure you are well covered, and use a good mask with filters designed to remove isocyanates. I think you need to cover your eyes as well. From memory these toxins are cumulative, so you can probably get away with using them at home for a one off type use. Not that I am recomending that you do this, as it is probably illegal to spray at home in most western countries.
 

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Discussion Starter #4 (Edited)
Craig said:
Just one minor point,

This:

Seems to contradict this:

Now, does anybody have any good tips about base/clear application?
Thanks for catching my typo. I meant it to say singles stage is cheaper and harder to repair, not cheaper and easier (that would be me). I corrected the original text.

As far as application, I agree with the last post. Don't do it at home. For the amateur, do the prep work yourself, and take it to a shop to have them spray the paint. The quality of the paint gun (the good ones cost hundreds of dollars), operator skill, and the cleanliness of the painting environment all determine the final outcome of the paint. You will get a better finish if you take a prepped car to any shop (even Maaco) and have them spray the base/clear for you. By the time you buy all the equipment (ventillation fans, spray guns, forced air respirator, paint suits, etc) it will be no cheaper than paying someone else. And, if you make a mistake with your $400/gallon paint, it could be more costly to fix.

In the future, I am planning on writing a primer on well, primers (and sanding), and how to prep a car for paint. But, if you really want to paint your own car, check out www.autobodystore.com. Len Stuart runs a first class store and bbs for people who want to do their own bodywork. He sells everything the hobbyist needs but the consumables for paint and bodywork.

Good luck,

Mike
 

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Mike,

A great "Primer" for paint systems. Another example of the wonderfull content available on the BB. Thanks...

Vantaaj said:
A question I frequently see is, what sort of paint system should I use? Base/Clear? Base only? Urethane? I will let you in on a little secret, it really doesn't matter, within reason. What makes great paint look great has almost nothing to do with the paint but rather the panel preparation prior to the paint, and the sanding and polishing after its painted... I will explain, perhaps with too much detail....
 

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Great writeup!
A lot of 80s-90s model cars seem to suffer from spotty clearcoat breakdown. Can they be repaired somewhat satisfactorily at home, or is that futile? What causes clearcoat problems?
 

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Vantaaj: Great post. Thank you!

I recently talked to a car painter who has worked on more than one continent. He swears that results of the same paint systems (sold under the same name by the same manufacturer) differ in North America, Europe and Asia. He said he excluded any environmental stuff (temperature, moisture, elevation, etc.) and believes that different formulas are being used (even for water-based paints) due to environmental constraints.

So, it seems sensible not to buy into any general manufacturer or paint system religion. Run tests to see what looks best. Trust your painter's experience (else you're in the wrong shop to begin with).
 

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Vantaaj -- excellent post!! I've been researching paint and the paint process for a few years and have never seen the paint types explained so clearly and concisely in one place before now. Thanks.

Suggestion: Make this thread a "Sticky".
 

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I agree that this should be made sticky.
 

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Mike / Vantaaj, I am much impressed with your detailed explanation of paints available today and their pros and cons. I've certainly printed out your opus and will carefully file. I'll be the first to admit when someone gives detailed information and makes it available to "the public" it is always open to interpretation and differing opinions. My only minor comment is there being no mention as to how important color sanding and polishing is to either single or two stage paints. Except for painting numerous wheels metallic silver then clear coating, I have little knowledge of the two stage system. I've been introduced to a local fellow who fabricates / restores / paints hotrods and since most all have at least two or more colors (as in flames, etc) he clear coats with up to eight coats with color sanding between every few coats. Most feel it isn't necessary to color sand or polish clear coat, but if one is looking for that deep shine, it is a must. Will add his minimum paint job is $13K.

I use only single stage and spend myriad hours color sanding and polishing the car.

I add this only in that most who are unknowledgeable with the process, don't realize how important this portion of the paint process is. Most inexpensive paint jobs use an inexpensive enamel and just enough paint is applied to get a nice over all shine. To do this and to avoid orange peel, the thinner the paint the better.

Biba
 

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Discussion Starter #13
Biba69 said:
I use only single stage and spend myriad hours color sanding and polishing the car.

I add this only in that most who are unknowledgeable with the process, don't realize how important this portion of the paint process is.
Biba, thanks for your comment. We are in violent agreement.

The quality of the final paint is determined by how well the bodywork is completed (mostly sanding)the prep work prior to paint (all sanding) and after paint is applied the color sanding (more sanding) and polishing (not quite sanding). This applies to all types of paint, single stage or two stage (base/clear).

When I get more time, I was planning on writing a primer on paint prep and sanding in general.

Mike
 

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Is rubbing back layers of base and clear coat before applying new layers called 'flow-coating’? I here this term used a lot with show cars but i never fully understood how it was done?

Thanks again for a fantastic post.
 

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Discussion Starter #15
GoldCloverLeaf said:
Is rubbing back layers of base and clear coat before applying new layers called 'flow-coating’? I here this term used a lot with show cars but i never fully understood how it was done?
I have not heard the term before, but a quick google results in the following definition. "In flow coating, the part is suspended, and the coating is poured over it. The excess material drips off and is collected for reuse." The site has more info on it. It may be an American vs Australian english thing as well.

Sorry I can't be more help.

Mike
 

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GoldCloverLeaf said:
Is rubbing back layers of base and clear coat before applying new layers called 'flow-coating’? I here this term used a lot with show cars but i never fully understood how it was done?

Thanks again for a fantastic post.
Vantaag, yes, it's an Australian term, I've quoted this from another Aussie forum after a quick google search.

At that time then "snick" or sand back clear coat. This can be a little complicated to someone not familiar with this process. Sand back the entire clear coat with a 1500 sandpaper either dry on a 2.5mm orbit sander, or with a rubbing block wet. This process will smooth out any peel in the surface. Then clean and prepare surface for respraying clear. Another 2-3 coats, then bake or dry again. This process is called flow coating and gives the best clarity and depth to a pearl refinish. the extra effort pays off. When dry, the whole car car then be sanded with 2000 followed by 4000 mirkon sanding disks then buffed for the ultimate sparkle.
Whilst he's talking specifically about a pearl paint job, the same process can also be used on a more conventional finish. I think the idea is to get the finish really 'flat' and free of orange peel.

Not sure why it's called 'flow coating' except that perhaps the finish looks like the paint has 'flowed' over the surface.
 

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Thanks Hamish, thats what i meant by 'flow-coating'. There truly is a lot of slang in this industry that varies from country to country!

Might give this a try on my 105 when the time comes, got nothing to loose but time with this application.
 

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Yeah, the slang is quite a bit different. I'm by no means a professional spray painter, but I have painted 4 or 5 cars at home (naughty me :) ) and some of the terminology Vantaag is using is unfamiliar to me.

What Vantaag calls 'lacquer', I think we call 'acrylic lacquer' (in a weird reversal of the Australian habit of contracting the name of everything to an absolute minimum) which is still readily available in australia, and what I have used to paint cars.

It also has a few redeeming features for the home painter,

* it is relatively cheap
* it dries really quickly, so it far less troubled by dust contamination.
* it doesn't contain really toxic isocyanates, so it won't kill you outright :eek:
* it's quite 'soft' so it's easy to wet/colour sand before buffing. It is also easy to sand out runs and other amateur boo-boos. In other words, it is pretty forgiving. (this softness is also it's greatest flaw, it is nowhere near as durable as more modern 2 part finishes)
* done right, you can still get a really good shine out of it.
 

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Hamish said:
What Vantaag calls 'lacquer', I think we call 'acrylic lacquer' ...
Read Vataaj's definition of "Lacquer" and "Acrylic" again. It would appear that his "Acrylic" matches your description of "Acrylic lacquer".
 

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Doesn't really sound like what I call Acrylic Laquer. Unless what he is describing is what we call nitrocellulose ( which nobody uses ) and acrylic laquer is the 1 part acrylic?

Aussies seem to describe automotive paints in 3 basic categories, Acrylic laquer, air dry enamel, and 2 pack ( 2 pack covering pretty much everything that is a 2 part type paint where you add a catalyst type hardener)

But, your post perfectly illustrates the confusion caused by the variations in terminology used to describe exactly the same thing :)

Maybe we should get a chemist to clear up the confusion :)
 
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