Sorry if this long. I wanted to list all the details.

I painted the 72 on Thursday. I tacked the car before I painted. The paint was PPG omni line green. I used a finish line II with a 1.4 tip with 45 psi going to the gun and 10 psi at the gun. The paint looked like water and it was worse when I reduced it. I sprayed it on the car and it ran like water. I adjusted the gun and it sprayed a little better. It took a few hours to spray the two coats on it. The paint looks like crap. I sent the wife to get more paint (I went through the whole gallon, two if you count the reducer)and the paint supplier said to use a 1 to 75% ratio(tech sheet said 1 to 1). That helped some but still looks like junk. It is different shades of green. My wife said it was the lights so I said okay. I then sprayed two coats of PPG DCU 2021 clear. The clear went on good in some areas. The rest of the car feels smooth but looks rough. I talked to the paint supplier and he said to compound/glaze it. I did this and it looks worse. I have cloudiness in a lot of areas and it still looks rough. I also have some orange peel.

I tried different lights at different angles and I still see different shades of green.

I followed the tech sheets to the letter and kept mixing it. I sprayed PPG primer two weeks earlier using a cheap gun and it came out great. I block sanded it and it came out nice and smooth.


The paint supplier says to use the next grade of paint. The cost for that is $240 a gallon. I paid $64 for the omni.

If I decide to repaint what grit sand paper do I use and how do I know when I have sanded enough?

Someone please tell what went wrong and what I can do to fix this mess.

I sprayed Omni once and it sucked.I ran it bad like you did. iT is like water.I would wetsand the whole car with 600 and reshoot it. If you don't want to spend the $240, try to find a suppplier who sell U-Tech.Its made by Azko Nobel,who also makes Sikkens. I bought a gallon of red pearl Metallic for a 2000 Durango.Dupont Chromabase was$260 for a Gallon of bascoat.The U-tech was $75! It is thicker,and its mixed 4:1:1 and it covers great. Its all i use anymore for overall paintjobs at my shop. Whatever you use just wetsand it flat respray the color then clear it.

I have only done 2 jobs with bc/cc but from my experience if you were having that much trouble with the base coat I would say step up to a higher quality paint and maybe a better gun or at least make sure the one you got is working right.
I sprayed 2 cars this winter with ppg dbc, one of them being my first experience with bc/cc and I found the base coat very easy to spray in fact it was almost like you could not mess it up no matter how you sprayed it. and I was spraying a dark blue mettalic. The clear was much harder for me to get right as I had trouble getting to lay out smooth without alot of peel but I think that was do to using a compressor that was marginal for the gun I have. For me it was definetly worth buying the good stuff. Although alot of guys have had great results with the omni and such. I just figured I needed all the help I could get so I spent the money for the DBC.

Thanks for the replies so far. Please keep them coming.

Throw in some lifting problems and you just described my first BC/CC experience. Oh the sags, color bleed thru, etc. Been there, the cheapo paint is not as forgiving.
I spray base colors with a 1.4mm hvlp gravity feed. I found thinner paint to spray best and still have descent flowout characteristics at about 28-30 psi. Try lowering the press and see what happens. Avoid under reducing anymore to "thicken" it up.
The white or cloudy look is water in vapor form in the paint film(BLUSHING)The way to avoid blushing is to spray at warmer temperatures (70-75 is ideal) and good air movement is a must!
Avoid spraying outside when its foggy.

I painted the car in a A/C garage. The temp out side was above 80 and sunny. I used an hvlp gun with a 1.4 tip. That is why I was surprised to see the cloudinees. It did not appear until I compounded it.

I talked to the paint supplier and he said get the good paint. He also said to wet sand with 600 until the car looks flat.

Keep the repiles coming.

Hi Steve, I sprayed my interior using the PPG DBC bc/cc. I also used the same gun as you. Is 45 psi that you used, was that with or without the trigger pulled. Please read the directions on that gun. You should have at least 60-70 psi coming to the adjustable regulator on the gun, then you should pull the trigger, the psi will drop on the regulator, then adjust the regulator to 23 psi with the trigger pulled. That will give you 10 psi at the tip of the gun. I followed that procedure and my paint came out perfect, it was my first time. Also on the clear coat the 2021 you used is fine, thats good stuff. I would step up to the DBC line and try that. I dont think I could of screwed up the base when I sprayed because the DBC was so simple to use. Also the DBC is kind of thin also. Good luck.

I will re-read the instructions. But I thought it said 45-50 psi to the gun and 10 psi at the tip.
The reg that controls the air flow to the gun was at 45 psi. The reg that I had on the gun was reading about 40 without depressing the trigger and 10 when the trigger was depressed.

Those who used the hvlp gun, Did you use the cup liner?

I did and every once in a while the paint would leak out into the cup. I would empty it back into the mixing can. It did not leak out of the cup but it was a little messy.

I agree with the above comments. I just sprayed a car using the Omni line you used. I ending up with a mixing ratio of 1:1/2 to get it to work. Another extremely good tip is to spray your 1st coat oh so thin. I sprayed my first coat the thickness of a guide coat and let it tack up for 30 minutes. My next coat was a bit thicker and let that tack, and finally my 3rd coat was what I would consider the 1st true coat. That Omni is very thin and if you try to lay it out like DBC it will run for the hills. Once you work the kinks out it actually lays out pretty nice. I had to repaint a few things, sanding them down with 500 grit.

Thanks again for the help. I will use the DBC. I will wet sand the car down using 600 grit until the finish is dull and reshoot the paint.

Steve, below is my "Basics of Basics" on paint atomization. Read it and fully understand it and you will be miles ahead.
To those of you who have read it before, I added some more info about the air pressure and and measuring it so it might be worth a re-read.

It sounds like atomization was you whole problem. The hazy look after buffing is proof, trapped solvents. The runs and modeling (the different light and dark shades) is proof, too much solvent "left" in the film because of poor atomization.
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Atomization basics
Being HVLP and low VOC products are the way the industry’s going I will be referring to them in this discussion on painting and paint guns. Most all basic issues dealing with HVLP can be applied to conventional guns, atomization is atomization. The HVLP just arrives at it differently.

The object of the spray gun is to break up the primer/sealer/paint/clear (I will call this “PSPC” from here out) into small particles and lay them in neat little rows on the panel being PSPRed. So the whole outcome rests on how well the gun is doing this. Picture the droplets of PSPC coming out of the fluid tip of the gun and then the air “slapping” them into smaller droplets.

You have two things that help you with this process, air and solvent. Solvent can mean something that is already in the PSPR from the manufacture or something the manufacture has told you to add to it. By the way, you should always mix in proper ratios as instructed in the tech sheet. The thinner (less viscosity) you get the PSPR or the more air you have at the fluid tip of the gun the more it will break up the PSPR. The target for you is getting the perfect balance needed. Too much solvent and the PSPR will have no body, fill, durability, etc. Too much air and you blow the PSPR everywhere but the car, poor adhesion, excessive texture, etc.

So, the answer is proper air supply and gun (and fluid tip) choice and how you adjust it.

With today’s high solids-low VOC (Volatile Organic Compound, you know the bad stuff that goes up into the air we breathe) products there is less solvent. And with HVLP guns there is less air at the cap to break up the PSPC, proper air supply and gun setup is more important than ever.

FIRST THINGS FIRST, your compressor and air supply.

An HVLP gun requires more VOLUME of air to operate (the V in HVLP, High Volume Low Pressure). Now you may notice that your HVLP gun is adjusted at maybe the same PSI as an old conventional gun, around 50 lbs at the gun (many HVLP guns are set at much lower though) so where is the “Low” in PSI they are talking about? It is at the actual air cap where the air and paint come out. An HVLP gun has only 10 lbs at the cap while a conventional has upwards of 50! This 10 lbs at the cap is something you have no way to measure. “AT THE CAP” means at the fluid/air cap where the paint sprays out. It takes a special air cap with a gauge on it. This “test cap” is used by paint reps, air quality control agents but only a few painters. I have never seen on in a body shop. I say this because the instructions that come with many HVLP guns tell you to “adjust to 10 lbs at the cap” all the while they give you no way of measuring the cap pressure. There is usually a “MAX PRESSURE” stamped on the gun or in the instructions. This “max pressure” is the maximum pressure you can set the gun pressure and still keep the cap pressure at the 10 lbs max at the cap the law allows (in most VOC regulated areas where HVLP is required). So the VOLUME of air (CFM, Cubic Feet per Minute) is the key to proper atomization with an HVLP.

If you have a gun that requires 15 CFM you will need a compressor and plumbing that will produce that at a very minimum. There are HVLP guns that need as little as 7.5 CFM so you can get good results even from a smaller compressor. Air supply is a complete subject by it’s self so lets assume that you have the air supply needed and move on to gun set up.

So atomization is the key, but why? Why can’t you just lay it out wet and let it “flow”, as an old painter will say. Picture a jar full of bb’s, they will represent well small, atomized droplets of PSPC. The gaps in between the bb’s is solvent. Now picture a jar filled with marbles, they will represent large, poorly atomized droplets of PSPC. The gaps in between are, you guessed it, solvent.

If you apply your PSPC in large poorly atomized droplets, what you will have is a film full of solvent. This can and will cause slow curing, shrinkage and dieback (the loss of gloss in the hours and days after application).

So, now that we have learned the need for gun set up, how do we do it? Lets start with the fluid tip choice. The newer high solids low VOC PSPC products need to be broken up more, so a smaller fluid tip is needed.
Basically you want the smallest fluid tip that will still allow you to PSPC the particular part you are PSPCing keeping the entire thing wet and in a fair amount of time. In other words a 1.0 tip would be beautiful for clearing one fender, but would be lousy to paint a complete. The application would be way to slow and the first panel would be way to flashed by the time you got around back to it. So you need to compromise, a 1.3 is a great all around tip, while a 1.5 though getting a little big, can get you by. If you read the tech sheet on the particular product you are shooting, it will have a recommendation for fluid tip size.
There are needs for other tips, for instance when shooting polyester primer you may need as big as a 2.3, but for urethanes and epoxies, the 1.3 or 1.4 will work great. If you plan on using a pressure pot or paint a bus, all bets are off and we would need to study a little bit more.

As an example of the use of a 1.3 tip I did a test once that proved the point well. I shot two panels of metal with a med solids urethane primer. One was shot with a 1.3 super high atomizing top of the line topcoat gun. The other was shot with a 1.5 (or a 1.7 I can’t remember) “hoser” primer gun. Three coats were applied and after a full cure (the one shot with the larger gun took MUCH longer to flash and cure by the way) the film thickness was measured. The one shot with the 1.3 tip was 2 tenths of a MIL thicker! The larger gun laid out the marble sized droplets full of solvent and when the solvent flashed the film shrank.

Air supply is a subject that could fill many pages by it’s self. So we are going to assume you have that covered and move on to gun set up.

You need to “tune” your gun EVERY TIME you use it just as you would tune a guitar before you perform. This is done with a very basic spray out pattern test. This very basic test tells you how your gun is atomizing and you adjust it to achieve the best atomization you can.

Lets do a spray pattern test:

Set the fan width as need (you don’t want to change it after you have “tuned” the gun). Turn out the material knob about 2 ½ turns. This is the “mixture” adjustment, kind of like the idle screw on a carburetor. The farther in it is screwed the lower the fluid to air ratio is and the smaller the droplets will be. The farther out it is, the higher the fluid to air ratio is and the larger the droplets.
Set the air pressure at the inlet to the gun to the manufactures specs. On an HVLP gun this spec is usually found on the gun and is the maximum PSI it can have while still maintaining the maximum 10 lb at the cap for legal HVLP transfer efficiency (68 %). You are now ready to do a test spray out.

Tape a piece of masking paper on the wall for the test. Hold the gun at a right angle to the wall, just as if you were going the wall. Hold the gun at a spread out hands distance (about 8” or 22cm). Pull the trigger to completely open for a split second and then close it. You want an ON-OFF wide open-completely closed in ONE movement. You should have a cigar shaped pattern with complete coverage in the center with fading coverage going away from the full coverage cigar shape in the center. The center should be fully covered without any runs. If you have runs, either you are holding the trigger too long, you are too close or the gun is simply applying too much material. In which case you need to screw in the material knob or turn the air pressure down. But most likely if you have turned the material knob out the 2 ½ turns and the air is set at the factory specs, you are just too close or holding the trigger open too long.

The droplets you see trailing off the center are what you will use to “tune” your gun.

Turn in the material knob to make the droplets smaller (and or raise the air pressure). The balance you need to attain is the smallest droplet size possible before you loose the coverage desired. In other words if you turn in the material knob too far, not enough material will be coming out to cover the panel! That balance of atomization and enough material coming out is what you are after.

Now, you’ll notice that I said, “raise the pressure to the gun”, while earlier I said to set it to manufactures specs. This can be anywhere from 25 lbs to 50 lbs. This gun manufactures “recommended pressure” is AT THE GUN. This means at the INLET of the gun, NOT at the cap and NOT at the other end of the hose, but AT THE GUN. If your gun doesn’t have a regulator on it, then install one. This regulator will tell you at all times what the pressure is AT THE GUN, which is what you need to know. Be sure to buy a quality regulator from a paint gun manufacture. Some cheapie regulators are going to rob air volume from your gun because of restrictions within them. This is something most home hobbyist CAN NOT afford do to small compressors. If you don’t have the air volume to atomize your paint, you are NOT going to get satisfactory results.

We are talking a very small adjustment. It is a fine balance in material to air ratio and a little more air than specified is okay. Even if it is an HVLP gun the inlet pressure recommended is to maintain the 10 lb limit at the cap. Well, about three quarters of the country has no regulations for HVLP use so if you go over the 10 lbs all it will do is atomize the material a little better. You may loose a little of the benefits of HVLP though. But remember you have a lot of control with the material adjustment knob.

After you are happy with the droplet size, DON’T TOUCH THE FAN CONTROL. It will change the PSI at the cap and will change the atomization you worked hard to get.
Do this spray out every time you spray as material change, temp, and humidity will necessitate a spray out droplet pattern test. Good luck!

http://members.aol.com/icantunderstand/hvlpdropletpatterns.jpg

Hi Steve, dont forget to read the instructions on the gun, you will see what I was talking about. At the pressure you were spraying the paint wasnt atomizing. Dont bother with the cup liner unless you need to spray upside down, the liner works great for those applications.

Thanks again. I will check the gun setting again.

Forgot about MARTINSR basics. Thanks.