Technical What kind of gun to paint a car with a small compressor??

As if there is only 1 way to get a good result....

 

Well sanding it all off will have to wait until Spring. It is -11 right now, and it is a unheated garage..

 

Al if it makes you feel better, after 5o plus years of doing body and paint I can tell you I would much rather strip cheap primer and start over verses laying down a top coat and having it go south! lol
Next time any of you think a spray can is a good idea , prime a piece of bare metal and set it outside for a week and then scratch at it with your finger nail and see how well it stuck! I know it is tempting on small parts and engine blocks. But epoxy primer and urathane top coats are your friend. And yes I learned these lessons the hard way! lol Larry

 

why you need to remove the can primer

 

I'm going to step in here and say there is more then one kind of rattle can primer. Like most other stuff, read the label. The cheap stuff is only good for temporary cover and needs to be removed. The better primer is good for painting a top coat over, but you need to be sure the top coat you are using is compatible with the primer you are spraying. There is a time limit as to how long of time there is between the rattle can primer and the top coat (same with a lot of the spray on primer), and that time window is pretty small. If the primer (and body filler) are exposed to a lot of moisture, you have trouble coming, most of both will absorb moisture and the metal under the filler and primer can start to rust. If you can mark the hardened filler or primer with a finger nail, its junk. Primer that has been on the car since last summer is probably not good anymore (rattle can or spray on, except some epoxy). If its been out of the weather, 3 months is probably the very longest I'd go.

Everything in the painting process has time limits, and most of those limits are based on hours, not weeks, or months, and none of them allow exposure to moisture.

If your willing to take the chance (I wouldn't) you may get by with spraying on a sealer that is compatible with the paint your using, before you paint. The time limit between spraying the sealer and spraying the paint is something like 8 hours max between.

The last time I did my coupe, all the body work was done in about 2 months, in my heated shop. My car was painted with an oil based paint around 5 years ago. Most of the car had body work done, but some of the oil based paint still existed. The oil base paint was certainly dry throughout, was in very stable condition and was surface sanded but nor removed completely. I was willing to take the chance of the sealer doing its job and sealing what ever was under it. We were doing 2 colors. We moved the car to my buddy's paint booth. Did a few sanding touch ups, taped the color separation line and all the edges & glass, then covered the rest of the car with a plastic drop. He sprayed the sealer (2 coats) on the exposed surface. About a 1/2 hour later, he sprayed the 1st color (the lighter color) 3 coats with the needed time between and it sat over night. In the morning we removed the plastic drop and carefully removed the taped separation line. Then we re-tapped the line, and covered the first color with a plastic drop and shot the 2 coats of sealer, then shot 3 coats of the 2nd darker color. The next morning we gently untapped everything.

I used acrylic enamel (a quart of each color) the hardener and thinner, and a gallon of sealer and the hardener (used the same thinner). The paint supplies cost me just under $300 at my buddy's cost (end of March last year). The acrylic enamel has a great shine and is a single stage paint that has been around for a very long time.

I'm not a painter nor am I a body guy, but I have pretended to be both on several occasions during my life. In my early years, I had a buddy paint an off topic car for a case of beer, it probably may have come out better if we had painted before consuming the beer... The 2nd car I had painted I paid a professional paint it, it was great, but costly. Then I had another buddy show me how to paint the 3rd car that one came out really good. I've painted several myself since then, I even painted my coupe the 1st time. This time around with the coupe was the 1st time since 1994 that I had someone else paint one of my cars. Gene

 

It depends what it is. I stripped my car to bare steel with a DA sander one panel at a time and like you I used a rattle can self etching primer to cover it. After that it was sanded and sprayed with various epoxy or urethane primers before I finally painted it with a single stage urethane many years later( after driving it for 7 years) It’s been 20 years since that rattle can self etch was sprayed under not ideal conditions and yet the top coat( which has been on for 7 years) is still hanging on and looks good.
Sometimes ignorance is bliss..

 

All I used was a self etching primer. If I have to sand it all off I will. I was going to spray that high fill epoxy primer on it to cover the scratches from the 36-80 grit sandpaper in areas. Other primer was just to cover bare metal. I will 320 the whole thing, or better yet if I can get it in at the College. They can.

 

If the car is in self etch, and im going to guess youve got 5300 series primer. you can just scotch brite the crap out of the car and spray that high build on. REMEBER, it will need 70 degrees for 12 hours or so. Plan on that part when you spray.
Shooting with your small compressor isnt optimal, but it can be done. Id watch craigslist, if you can find a cheap used compressor, or even a tank you could use multiples, let one charge while you drain one, or manifold them together.

I shot my unibody with a 33 gallon compressor and hvlp gun. I had to give it a few minutes here and there to catch up. Id shoot about a quart of material, and while mixing the next batch, let my fan take out some cloud from the air and compressor catch up.
I had my compressor just outside the door, kept it a little cooler, and let it suck in clean air instead of overspray, so maybe itll live longer.

You can do it. Its not optimal, but its doable.
Id really keep an eye out for a cheap compressor, even if you just use yours to charge it as a reserve tank, or look at renting a gas powered on on a trailer for a day.

The tamco single stage works sooooo nice! way better than the case of rattle cans idea, even if you have to cut and buff.

 

Bottom line is you are taking a chance spraying over what you have on there now. That is your choice that no one can make for you. It may turn out fine, it may fail as soon as you/they start working on it or it may fail down the road there is no way to know for sure. That is why no reputable shop would touch it as is. It's your time and money so you need to decide how much of each you are willing to risk as I am sure none of the "just go for it" guys on here are going to be forking out either of their's if it goes bad.

 

^^^^ well said and good advise. Thanks for joining in on these topics sir. Regards, Randy


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Rattle can primer is intended for rattle can paint.

Why not do it right? Sand off the old primer then reprime and paint. Shortcuts in paint prep can result in a lot of regret.

As far as the original question - I had good results with a Eastwood hvlp gun using a smaller compressor making sure I did not get too low on pressure by letting the system “catch up”.

 

Should I sand it back to this yellow that was on it when I got it??

 

Wow there is other primer on there that you don't know what it is or what it has been exposed to? You need to take it back to bare metal.

 

You're gonna have to wait for warm weather no matter what you do!

 

Youre shooting rustoleum, you can control the flash time if you use real enamel thinner. Or you can slow it down with the general thinner, acetone is fastest, naphtha is medium, mineral spirits is slow - like days slow.

Use valspar enamel hardener, or any enamel hardener

Use a slow thinner. Pause between passes and let your compressor build. Use a heavy overlap pattern. Itll lay down. Rustoleum is very forgiving, consider it levels itself at full strength when brushing it on. The slow reducer will take longer to cure, rustoleum or industrial enamel in general takes months to cure for a good cut and buff.

Ive painted equipment with industrial enamel and too small of a compressor before - behind a barn with a pancake conpressor and 200' extension cord Slow down the paint and pause between passes. Other than speed of spraying its not much different than just brushing it on when it comes to rustoleum. I prefer valspar tractor enamel ( farm store) to rustoleum in that range of paint.

 

He said he was looking at single stage Tamco (which is a urethane), not Rustoleum.

 

If I have to bring it all the way back to bare metal. Can I spray on something like that Dupli-color out of a spray gun to cover it??

 

I want to paint it White. What would you suggest I paint it with?? Doesn't have to be urethane..

 

Maybe I should ask. After I strip it all down to bare metal. What would be a good Primer to spray on that bare metal??

 

What are you trying to achieve? If all you want is some cheap colour on it, get something really cheap like Rustoleum and paint it. If it fails you are out little in time and money. If you are trying to do a half decent job strip it to bare metal spray an epoxy and work it up from there. You should probably do some research on paint and body if you are trying to do a decent job and figure out how things work.

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I don't think the point is getting across. I say at the point you are at, it seems you just want a shiney coat of paint. That primer looks like it may be urethane. I remember the old yellow stuff. If it was sanded properly before it was put on, which by the way you should have been able to tell when you sanded it before, although I am confused between that pic and your avatar. Sand it and continue on with your bodywork, prime it again with some good urethane sand it and shoot it, however you decide. JMO. Lippy

 

I knew I shouldn't have posted on this. LOL

 

Depends on what you find under the primer. If the metal is pitted you'll need to clean out the pits with some kind of rust remover, then clean and prep the metal to neutralize the rust remover. If it's not pitted or once the pits have been dealt with I have used and recommend Eastwood's DTM Primer. It gets a really good bite on the metal and you can apply body filler over it if necessary. The only drawback is that it takes a long time to fully cure so that it can be either sanded or roughed up for body filler. It's an epoxy so cold weather isn't going to help that situation at all.

EDIT: Judging by the color it looks like your body was coated in DP40 which was and still is an excellent product. It has very good short term protective qualities...but it does not prevent rust from forming beneath it if exposed to the weather for extended periods of time.

Primer is formulated and intended to improve the adhesion between the gloss top coat and the metal and/or filler substrate. It is not intended as a top coat. Primer is porous and will allow moisture to penetrate through it and cause rust to form beneath it. It's the hidden rust that is your enemy. If the bond between the primer and the metal is compromised by hidden rust it will eventually lift and ruin your glossy paint job. Those giving advice are not trying to tell you what to do, we're just trying to help you from being disappointed later on.

 

The problem is he really hasn't said what his point is. Once he actually says it might help. Urethane primers do a terrible job of corrosion protection so if it's a urethane and has been sitting outside there is a good chance corrosion has already started under the primer. That's the problem with having no idea what has been done before you purchase a vehicle. Not trying to discourage him but also don't want the guy to put a bunch of work into something and have it start failing a year down the road.

 

Please, be careful of the advice you're getting around here. The truth is thousands of cars have been painted very successfully using rattle can primer. These things depend on what your goals are. There are guys that paint their cars with brushes, or rollers. Holy crap some of these guys would go apoplectic over it! Sometimes threads on the HAMB are over the top. Asking for advice on the HAMB is a crap shoot. A guy can post a thread asking for help with adjusting the throttle linkage and by the time the thread is done he's being convinced he needs a complete overhaul. Somebody repairs an engine by boring 1 cylinder instead of all, and guys here can't believe it's even possible. Here a guy asks for advice on a spray gun to match is compressor and he's being convinced to strip his car to bare metal. WTF???

The other guy was right, it's your time and money, you have to decide what your goals are and what your resources are, and act accordingly. I assume by the nature of your original question you don't have unlimited resources. Well, that guy's not going to pay for your supplies, or your time. At the most you may get a "like" out of him when you're done. Wow! That will surely make it all worth while, right?

I can also tell you that many, many cars over the decades have been painted using rattle can primer, and even rattle can top coat (OH, the horrors!). And one of the most famous hot rods of all time was painted with brushes, by members of the paying public at a hot rod event. Google Jake Jacob's tub. I think he probably did it like that as a response to people telling him he couldn't do it.

 

Okay. When I can start sanding again. I will get a Quart of Epoxy primer..

 

Well I'm glad everything is straightened out now.

 

I'd still like to know what successful means.

 

It means the goal of the builder was met.