Re: \"RUNS\"
From the sounds of things I'd sand it all and start over. Sanding flake is never a good idea so you should start from scratch. The gun should have had some sort of manual that says it needs 'X' psi at the handle to give 'y' psi at the air cap. I'd bet it's somewhere around 30psi at the gun handle. If you've got a regulator/guage at the gun handle, leave it wide open and then adjust the regulator on your compressor so you get the required psi.
Here's a post from Rex (I think, coulda been someone else) that I copied from the old forums. I couldn't find it on this new board.Hopefully it's some help.
-Stretch
Your most important issue is air supply.Not only do you need a compressor to keep a constant psi but volume is just as important,especially with HVLPs.The days of 1/4" airline and fittings are pretty much gone,you need the volume that 3/8 line and fittings supply to atomize these hi-solid voc compliant clears properly.You can work around it but it's work and aggrevation you don't need and can cause problems like solvent popping and dieback from hosing it on thicker to achieve flow-and we're not getting into temp reducers or mixing.Also,at-the-gun regulators can throw a kink in your airflow by necking down your 3/8 line to 1/4 negating the extra money spent on the larger hose and fittings.If you run a regulator like I prefer to do buy a good one with large holes and run it wide open,adjusting the pressure at the wall regulator.This way you have full volume working for you but if you need to back down for any tight areas like some of these #@*&$^ bumpers you're not feathering the trigger with full pressure blowing puddles in the clear as you try to layer it up wet.If you don't want a regulator you can do the waterhose trick in these instances,fold it in half and squeeze.I don't do it because it breaks down the inner core prematurely.Speaking of that,getting odd sized black chunks in your paint and the hose is a few years old?That's a good posibility.
To set up your gun takes a few minutes but saves a ton of grief.HVLPs benefit from the use of an aircap guage to dial in the inlet pressure so you have the recommended aircap presure-usually 10psi.The prob is they're expensive so the following setup works,you just need to play more with inlet pressure.Also,don't be surprised if you excede the inlet pressure to achieve results,I've seen HVLPs take 5 or more psi inlet pressure than advertised as max to acheive that 10psi cap pressure with an aircap guage.So,the first thing to do is get a large sheet of paper,chunk of sheetmetal,anything to throw patterns on and lots of them.Now mix up 6 or so ounces of the material the gun is used for.What you're going to do is throw a pattern check on the surface (and verticle so hang the paper etc. on the wall) ,with the pattern adjustment and fluid adjustment wide open ,with a full pull of the trigger and complete release all in one motion,no run the air and then pull the fluid through-off,full trigger,off.Don't look at your pattern,look at the size of the droplets on the edge of the pattern.What you're trying to adjust is the droplet size to be the smallest possible.Initially all you want to do is play with your inlet pressure and fluid flow while basically maintaining your pattern.Once you get a small droplet and your inlet pressure is within range for the product specs and the fluid is a respectable setting you can adjust your pattern knob in a little to even out an hourglass pattern.If you really have to run in your pattern knob alot you're probably choked in too far on the fluid so come out some,don't sacrifice a wet,nice pattern for the ultimete small droplets.HVLPs are going to take a little longer for this process without an aircap guage because you'll be experimenting in unknown ranges and adjustments.For example,a sata Jet90 might be running 10psi over max inlet with the fluid choked down to 40% and be good.
Test #2 is your wetness.Turn your aircap 1/4 turn for a horizontal pattern and with the same trigger stroke blow a pattern for 1 second with full trigger pull and release.Now watch the drips.You should get basically an even paint slide the length of the pattern.If it's faintly heavier in the middle it will fly but go back and tweak it to try to get it even from end to end.An older gun wont always adjust out but a new one should be dripping evenly end to end.
The reason you want small paint drops is coverage and flow.Think of it as trying to cover your floor with oranges or bowling balls.The oranges will cover with less coats,be thinner,and lay flatter than the bowling ballsNow,if you take this from the sealer and add in basecoat and clear you can see why at the end it'll work out nicer,using the bowling balls you're piling it on and exagerating orange peel (no pun intended) from start to finish way in excess of the smaller orange droplets.Hope this helps and feel free to add in everything I missed.
