I have decided to take the plunge and try the rustoleum paint job on my old honda. I have put one layer of primer on and I have a slight issue.

My setup consist of a 5hp, 20 gallon air compressor fitted with a water trap and air filter, and a conventional paint gun. I did a test and at no time does the compressor drop below 100psi in the tank (running 75psi to the gun), even in a continues spray application. This is my dad's old paint gun and I have seen the kind of paint jobs it can do...it may be an old conventional, but it can lay out some nice work. Temperature outside was 85 degrees. at around 80% humidity. Car was painted in a makeshift paint booth with plenty of ventilation. I am using rustoleum professional white primer mixed with about 50/50 acetone. I will ultimately be painting the car back the original red using rustoleum professional.

I wet sanded the old paint with 600 grit and scuffed it up real good. This is a shot of 1 coat of paint after it has dried. As you can see, I have very tiny bubbles in the paint and the paint is rough like sandpaper. I kept the file full size so you can see.

http://truckplace.com/od/100_0393.JPG

Today I have sanded it down with 600 grit wet again, and I will soon be going to get 1000, 1500, and 2000 grit paper. However, just sanding with the 600 has gotten rid of almost all of the bubbles. If you look real close at the paint you can see tiny pits, but it isn't nearly as pronounced as it was. The paint is also smooth, but you can still feel a slight roughness to it (I do realize that I have sanded with a pretty rough 600...). I believe that I will be able to sand this perfectly smooth. However, my question is what caused this? I want to be able to solve this now before I get into putting base on it.

Here is a picture after sanding with 600. Can't see much of anything.

http://truckplace.com/od/100_0399.JPG

Overall view

http://truckplace.com/od/100_0392.JPG

Anyone have any ideas? Help is greatly appreciated!

 

I'm just a beginner at painting as well and I'm not all familiar with Rustoleum Professional paint products. Does the rustoleum paint actually call for acetone as a thinner? A couple of ideas as to why your paint turned out this way, was it was not thinned enough or wrong tip size, so it was not properly atomized. Did you filter the paint prior to filling your spray gun. You may want to make sure your paint gun is truly clean, there may be some blocked air passages in the gun and you may want to play with your gun settings and incoming air pressure to see if this helps. As you can see there are many things that can effect your paint job and I have not even mentioned them all. Good luck and let us know what you find out.

 

Put on another coat of primer and a trace coat(mist some black primer or rattle can of paint) then block it down. This will show you all the spots that may need work and you wont miss sanding anything. If needed get some glazing putty to fill in any pits. 600 grit should be more than fine enough to paint over with acrylic enamel. Just remember to seal it before you paint with something like DP40.

 

I thought Rustoleum called for mineral spirits as a reducer.

 

looks like your spraying to dry.

 

I have never used rustoleum, other then to spray bomb my bicycles as a
kid.

But the fact that it was spraying dry and rough, and plus the bubbles could possibly solvent pop, where the top surface skins over and traps solvents before they can escape, leaving bubbles then escape though the dry top surface, and when popped create little pinholes in the surface. Did this occur awhile after application, or was it occuring while you were appling?

Other thoughts would possibly be moisture in the airline (sounds like you have that covered with a water trap, but just to be sure, it does no good if mounted right at the compressor, it should be located at least 25' worth of airline away. Another thing that could cause bubbles is air entrapment, either by a poor quality paint-not proper additives, wrong application or mixing.

My first thought like others was solvent, particuarily one that is possibly too fast, and to try one that is slower. Acetone I believe is a fast solvent. If others say mineral spirits i guess try that, but I don't see why you couldn't use a slow urethane reducer in it, which should allow the paint more flow time, and the surface open longer to allow solvent to escape. General rule is you can use a better grade solvent, but a lower onet can leave you with a curdled mess on your hands or lead to poor application. Found out about the curdled mess when I was still young and tried cleaning my spray gun with a cheap paint thinner from the hardware store.

But hard to say for sure, Rustoleum is not made for refinishing vehicles, nor will it stand up to the elements, or use automotive grade pigments, its normally used for stuff like lawn furniture. If people only realized that there are some cheap urethanes out there, if you have the ability to spray, and can properly protect your body, and have good ventilation while applying, that even though not the best paint in the world, depending on color can be had under $100 and would be a lot longer lasting in the elements and more durable then rustoleum could dream of being. Or you could check your local auto body suppliers shelves, and see if they have any mismixed paint or paint not picked up available at a reduced price. Seems to me if you are putting the time in to prep and paint a vehicle, you should use something meant for automobiles that will hold up to the elements for awhile, and is compatable with automotive paint. Rustoleum will need to be stripped back off if you decide to use an auto paint in the future.

I'd try a slower solvent, and start out with the viscosity, so that when you dip a paint stick into the thinned paint and pull it out, it takes about 3 seconds or so to stop running off the stick and starts to drip.

Did you read through the super long threads on moparts? I've never read through the things, but am sure some have sprayed the stuff and may have some tips on what worked for them.
moparts: New Paint job on a budget thread Part III

 

Here are some sites about using rustoleum for painting your vehicle. They all state you should use mineral spirits for your thinner. The first site has a thread about spraying your car with rustoleum.

Spraying

Home

 

Rustoleum doesn't fade too bad. I brushed an old mud truck gloss black (including the entire undercarriage) about 5 years ago and it still shines like new. 5 years isn't a lot in the paint world, but considering the harsh treatment it gets, that is good enough for me.

Rustoleum calls for acetone, which is why I was using it. I did quite a bit of reading on it before I even started, which is what gave me the idea in the first place, and I got mixed opinions on using acetone. I am using cheap thinner for cleaning the gun, but (realtively) exensive for mixing.

Through some long experimentation, I did learn the cause. I was using too much acetone. I dropped my mixture down to about 70%/30% and now it lays on nice and self levels pretty smooth. I can see reflections and a shine to the paint sanding with 1000, which impresses me for a flat white primer. I think that this should turn out pretty nice as I am ready to start spraying base later in the week.

My plan was to pratice with cheap paint until I get the hang of it before buying expensive car paint, which is working out pretty good. Quite a few people have had very good luck painting with rustoleum and I believe it should work out alright. I have painted many things with rustoleum myself and it turn out very well, just never the outside body panels with an attempt to look nice.

What do you mean by "spraying too dry?"

 

Too much air pressure , moving too fast , too far away ,,single coat instead of double coat ,,,,