Spray primer in a can

best out there is dupli color etching primer, bar none, only problem i had with rustoluleum is if you re coat it it will blister on you, you have to wait a week for full cure and then seal it, just give dupli color etching a try not only does it etch it seals and covers great and very sand-able,
 
Things to think about with paints.

I am not great expert, but in the years of poking around and what I know from experience.

A couple of concepts must be kept in mind. Paint attaches to metal through etching. Etching can be mechanical as in sandblast or sandpaper or chemical with an acid. Paints attach to other paints via mechanical or chemical. Mostly the old paints such as lacquer melt the previous layer. Modern paints rely on a "rough' surface. When you paint a over a 2K paint during the recoat window it will attach to microscopic holes in the paint that close up as the paint cures.

Etch primers are used way too much. They can be attributed to more failures then you might expect. Their main purpose in life is to allow one to paint unetched metal without the sanding step. The problem is you must get the correct thickness of paint and epoxies may not cure properly if the acid does not get properly neutralized.

A real 2 part epoxy directly to properly etched metal gives the best adhesion and a moisture barrier.

The oil based paints are always going to shrink as they are forever outgassing. If you cover the oil based paint with something that shrinks at a different rate the paint will crack and peel. My brothers coupe is a wonderful example of this problem.

The modern 2k paints are great as they are very stable, do not shrink, and seal the metal. They are easy to apply and you only need to be careful about the temps you spray at. I have been mixing up very small quantities quite successfully. I have been doing small paint jobs by using stainless steel table and tea spoon measures. For slightly larger jobs I just a Devilbiss bumper demon. I also got a real cheapy bumper gun, but there is a night and day difference with how well the Devilbiss sprays. The resale on the bumper gun is very high so you could buy one and resell it on Ebay at a good price.

Rustoleum has its place for those on a budget and other limitations in being able to paint. I have been using it on small stuff and items with a limited view. I have to balance getting stuff done and done better with a better paint.
 
I know nothing about paints, primer or otherwise. However, I've always heard that metallic primers were the best. That's why so many are colored red like or because of the Iron Oxide (rust). But what about the aluminum paint (silver)? That should be a good primer too. And don't forget the zinc-chromate (green) used throughout the aviation industry. It seems like an excelent primer, altough it's not widely available. Exactly what does a primer do? Protect from rusting? Provide a "sticky" surface for the regular paint to stick to? It seems to me that we want rust protection first on these eighty year old "rustbuckets" What exactly is Primer's job?
Terry
 
Terry said:
I know nothing about paints, primer or otherwise. However, I've always heard that metallic primers were the best. That's why so many are colored red like or because of the Iron Oxide (rust). But what about the aluminum paint (silver)? That should be a good primer too. And don't forget the zinc-chromate (green) used throughout the aviation industry. It seems like an excelent primer, altough it's not widely available. Exactly what does a primer do? Protect from rusting? Provide a "sticky" surface for the regular paint to stick to? It seems to me that we want rust protection first on these eighty year old "rustbuckets" What exactly is Primer's job?
Terry
Click to expand...
To seal the metal Iav found nothing wrong with authmotive Rustoimem.
 
A primers job is what you need it to be.

Metal needs special stuff in the paint to promote adhesion. Ford used a different enamel mix for the first coat.

The extras that do corrosion control vary depending. For aircraft you need the Zinc chromate but that chromate is not a nice chemical these days so it is used less. Epoxies adhere well and create a tough barrier that does not allow moisture through. So if you properly killed the corrosion you will not get more.

Chemicals such as chromate and phosphoric acid that bind the surface atoms so that they do not want to bind with Oxygen (greatly simplified looked it up in detail on the web).

There are products such as PickelX or Ospho that are easy to use. They will kill the very light surface rust. They may not do enough for the small rust nugget in the bottom of pits. These nuggets in the bottoms of pits can even expand enough after a coating with epoxy to break though the epoxy and allow rust to continue to grow.

Products like POR 15 do not stop rust. They chemically bind to the surface of the rust and seal the rust from more moisture. They do not prevent the existing rust from using up the moisture they had when coated. These products are designed to go over rust. Rust does not adhere well to the base metal.

Paints and chemicals are tools.
They each perform a specific job. You need to know and understand their job and use them appropriately. No different then the other tools in your garage.

There is a lot of not so right information about paints and how they work. It is possible I might have mixed up details. As always I invite you to do your own research. I have found SPI paints to be extremely helpful in making good paint choices based on science. I wish I talked to the owner 10 years ago. I have made some poor choices in the past.
 
Though the brand and type is important, what's most important is the PREPARATION. And this subject, though simple, is next to impossible to get through thick heads. You can make a spray can job last 30 years or longer if you get your parts chemically clean end keep them clean throughout the painting process. Clean your bare metal with a grease and wax remover, then DuPont 5717S and CLEAN towelling, don't thereafter touch it, blow on it or expose it to anything dirty or oily. No primer can penetrate a contaminated surface and bond to the substrate. Don't feel scolded, this is for the thick-heads. The best aerosol etch primer that I have discovered for excellent results, fast drying time, coverage and user friendliness is Dupli-Color 1690. I get mine from O'Reilly's. This is not a filler primer. If you want to fill and sand small scratches, use the above preparation and prime with Dupli-Color FP101, then seal with 1690. One thing I have discovered with 1690 is that it is very fast drying and after a couple hours or so of drying time, it is best to lightly scuff it with red Scotch-Brite for assurance of good adhesion of the color coat. Clean the dust off of the parts with a clean rag lightly dampened with grease and wax remover before spraying sealer and before spraying the color coat. A good all-round towel is Scott “Rags in a Box” and they are also handy for about every shop use except for the fact that lacquer thinner and some other thinners will cause them to release fibers, so they are bad luck to clean out a paint cup with. JH www.olympic-speedsters.com
 
Thanks Guys! Especially Kevin! I had never heard of SPI before and I went to several threads (sites?) relating to automotive painting. In one such forum a guy named Chris (who seemed to know what he was talking about) said stay away from anything in a rattle can and to take the trouble to learn about epoxy paints. He said that "Rattle Can" primers lose their adhesion after a while. And that most are Laquer based to maintain shelf life. Makes sense, I guess. The general gist of what he wrote was "Do It Right!". Avoid bodily contact with all of this stuff, wear gloves, goggles, and masks.
Terry
 
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