Problems with paint gun

I was doing some painting on sheet metal today and had a heck of a time getting the gun to spray well. The paint would float away after making contact with the sheet metal causing overspray. I'm running about 10-20 psi with the Centari Acrylic Enamel paint.
I thinned it 8:2:1, but could my problem be that it was still too thick and hard to spray? I sure used up the whole pot very quick and was disappointed that I probably wasted half of it...
I've painted several tractors but have never really been taught how to troubleshoot problems like this. Any insight would be appreciated.

What type sprayer do you have? You might take the gun apart and thoroughly clean it. Sometimes they get enough paint built up inside of them it prevents the paint from spraying properly especially if you used the same gun to spray primer. Primers have a lot of fillers and easily stick to the inside of the sprayer. I use a old junk gun to spray primers for that reason.

It's a vacuum feed with the hopper on the bottom. I use it for primer also, but that hasn't caused any problems until now. I started using lacquer thinner to clean the gun and I've noticed old pieces of paint shooting out of the gun. I've checked all the passages and they're clear.
Here's something I didn't mention before, when the paint did build up on the sheet metal, it looked powdery and not wet like it should...???why

Where did you find Centari? I wasn't aware it was even made anymore. What hardner did you use?

I had a gun one time that I used only a flat oil based enamel in it. It had a lot of solids in it like primer does. When the job ended I thoroughly cleaned it and used it for wood stains for several years. Then an employee broke my good gun and I needed one for shooting clear finishes. I took this gun apart and thoroughly cleaned it again and started using it for the clear and continued to use that gun to shoot clear lacquers for a couple of years. Then one day I was spraying the finish coat on a mahogany table top and it spit out specks of the oil based flat paint I had used 10 years prior. Ever since then I have guns that only get a clear finish put in them. Sprayers are just impossible to get completely clean and some finishes are just harder to get out than others. The best chance you have of getting the gun clean is to completely take it apart and put it in a container and soak it in lacquer thinner. Then use a small stiff paint brush to clean it. If your gun is spitting out specks of dried paint its a good indication the gun needs more cleaning.

As far as the gun spraying like powder, if there is any obstruction in the sprayer preventing the paint from drawing, it's like you used a nozzle too small for the finish you are using. What happens is it sprays more air than paint and the particles of paint just dry before they reach the surface you are spraying. You have to either fix the sprayer so it sprays more volume of paint or thin the paint more so it doesn't dry before it gets there. Some finishes like lacquers you can add retarder thinners to it to make it flow out and dry slower.

The paint you are using I would suspect the thinner for it is rated for different temperatures. If you use a thinner made for winter in summer it can cause the finish to spray like powder because it is formulated to dry faster.

CARQUEST. They could be using another brand and throwing the centari labels on it.
Overall gloss hardener (centari).

That ole Centari with 793 hardner was one of the easiest to spray so it must be a gun problem.

I bought a new 3 gun set-up and the paint still did the same thing, it splattered out onto the sheet metal and then slowly morphed into a shiny finish. I've used centari paint before and it has never done this. I'm used to it going on with a wet look immediately.

You said below that you were using a siphon gun with the canister on the bottom. If you are only using 10-20 psi with a siphon feed gun it won"t work out too well.

It was HVLP though. And when I used a new gun I bought (HVLP gravity feed) The paint sprayed the same way as well, splattery.

10-20 psi is also too low for HVLP. The pressure should be on the gun or at least on the info that came with the gun. There is a great variation, 30-50 PSI depending on who made the gun. The correct pressure for the gun is etched in stone, you do not need to ever change it, provided you mixed the paint right. With cheap paint you might have a problem and need to adjust. However, the paint coming out of the gun is supposed to be 10 psi -- not the amount going in.

Read the manual that came with your spray gun. It should tell you what your pressure at your regulator should be. On my gun its 35psi. If you buy paint from PPG, Martin Senour or Dupont it will tell you on the paint can how much thinner to use. Hal

This gun says 20 psi max.
The Dupont tech sheet states that HVLP should be at 8-12 PSI. I know the paint was mixed correctly 8:1:2, and I had to add some more thinner because the paint was just to thick.

Set it to what the gun says, the max figure is the one to use, it does not vary with the type of paint -- the pressure is reduced to about 10 psi inside the gun.

Adjust your pressure as explained <a href="http://rodnh.byethost12.com/misc/pressure.htm">here</a>