I just painted my trunk lid and it orange peeled terrible. I did 3 coats so from what I have read I will be able to wetsand/buff it and it will work out but I need some advise on what too do because I have the whole car to paint. I have an ACCUspray HVLP siphon feed that I am using for the first time. I did a lot of reading and Im concerned about air. the book said inlet PSI should be 35-40, is this with or w/o the trigger squeezed. From some other things I read, the most likely culprit for me is the tip size. I have a .7 and a .9(I used this one) and the tech sheet said use 1.1-1.3? for the clear. For the base I used the .7 and it worked fine even though the tech sheet said use 1.0. I did not realize what I had in it until I was done. I did not test shoot a pattern on the wall where you squeeze the trigger fully and let go, because I had not read that before but I will try it when I paint again. My big question is whether or not I can make the .9 tip work by adjusting it or do I just need too get a new tip? I was planning on painting the front clip tommorow but if I need to get a tip I will hold off. So if any of you have any tips or answers for me I would really appreciate it.

I just realized one more thing. when I changed the tip I only changed the screw in part on the outside that has the hole in it. I did not realize that I had a different tip for the needle as well. That means I used a .9mm tip(dont know what it is called) and .7mm needle. I dont know if this would have helped or hurt me. Thanks

Using the .9 tip with the .7 needle KILLED you. It was like putting a 24 inch wide door on you house where a 36 inch door use to be without changing the hole!

Are you sure you are not working with a "pressure pot" gun where the cup gets pressurized? Anything less than 1.0 are never on a "regular" gun of any kind. Either a it is a little touchup gun or "air brush" or it is pressure pot.

Let's figure that out first.

Brian, yes the pot is pressurized. I have painted with a gun just like this before and I really liked it but I was not painting bc/cc and the guy I borrowed it from set it for me. Now I have my own and starting over. At least I know ONE thing that I did wrong so far. Thanks

You should also invest in a set of high flow air fittings for your hose(s) and compressor/filter/regulator, and whatever else you might have inline. I was having problems with orange peel when I first started using my Sharpe SGF98HVLP, but the high flow air fittings and a good Sharpe filter/regulator (read BIG) on the wall took care of the problem.

I painted some more tonight with the same results. The base turned out good and the clear has bad orange peel. I used the right tip this time. I messed with air pressure, amount of paint going through it, more thinner, fan adjustment. Nothing helped, I guess I didnt try the right combo. Any ideas?

Just out of curiosity did you get the correct tip for the needle or the one specified in the tech sheet? It will make a difference. How about following flash off times(tech sheet) between coats? Correct mix ratios? Lastly airflow in the area your painting, also makes a huge difference. Just some ideas.

Click on the link and take your time to read it. I doubt you will find a recommendation for the tip size in the tech sheet, pressure pots are just not that common in collision repair. I looked thru all the tech sheets I have and found that most urethane clears recommend a 1.0-1.3 tip for a pressure pot HVLP gun. As I remember, the pressure pots always had a smaller tip like your -1.0 tips. All I know is if you adjust your gun to the directions in the "Basics" and understand why you are doing it, you will be able to do it.

Another issue is what Darren brought up. If you have poor air supply, you have jack.
If you have a little compressor, OR poor plumbing, like too small of hoses, too long of hoses, poor water traps that rob air VOLUME (the V in HVLP) than you are stuck. The pressure pot HVLP is not as sensitive to these issues as a gravity feed, but it can still be the problem.

If you are running out of air, the gun is just not going to atomize. The HVLP gun relys on a lot of VOLUME of air to break up the particles of paint as they come out of the gun. You may be able to cheat by upping the pressure to the gun (not the pot) past where it recommends to break up the paint. In fact, if your gun has an adjustment to pot pressure, this could be your problem. If you have that pressure too high, it PUSHES paint out the tip and if there isn't enough air VOLUME coming out the tip to bust it up, you have poor atomization. I havn't used an pressure pot HVLP in years so I don't have much to offer you.

I just looked at the SHARPE book and it mentions with the 998HVLP pressure gun that they have two tips, .08 and 1.2 with the .08 being a recommended size for "all automotive colors and clears". It also says that the "cup pressure regulator adjusts fluid delivery speed for perfect atomization". As I remember there is a control for cup pressure on my pressure cup HVLP (hanging in my garage as vintage art smile.gif ) All I do know is that this SHARPE 998 only needs 7.5 CFM (about half as much as a SATA NR2000 for instance) so that is in your favor.

What brand and model is the gun you are using?

"Basics of Basics" Atomization CLICK HERE (http://www.camaros.net/forum/ultimatebb.php?ubb=get_topic;f=3;t=002548)

I have a big air compressor so Im confident that is not a problem at all. Plumbing on the other hand could be a problem. I have enough volume too operate a big 3/4" impact that will do anything so I think I have enough air. I do put one of those disposable orange water separators at the gun. My gun is an Accuspray model 19. I still have a few questions about air. I dont fully understand what everything needs too be. The book says 30-35 PSI at the gun. Does that mean that I can have 150PSI going through the hose and regulate it right at the gun? Thats the way Ive been doing it but I also tried regulating right out of the compressor and that didnt change. The other thing is the air guage on the gun, Do I want it too read 30-35 while it is sitting there or with the trigger squeezed. Finally the book says to use a .7 tip for medium solids clears and a .8 tip for high solids clears. Im using PPG concept 2021 and the hardener says "high solids" on it but I dont have a .8 tip, only a .7 and a .9. Thanks for everyones help and the link was very helpful.

Mark,
Something else that will cause orange peel is a reducer that is to fast. I don't know what temp. you are spraying at, but you might try a slower reducer. Your clear could be going into set before it has time to flow. Remember though a slower reducer can get away from you and sag or run. Be sure you wait 15 minutes between coats, that way the next coat will be pulled into the previous coat. That will also prevent solvent pop.
Fred....