Screwed up the Epoxy Primer finish, why?

[srsupertrap]

I sprayed my gas tank this afternoon with Omni MP170 Epoxy primer and I ended up with a textured finish, that would be orange peel right? :o

I used a touch up gum with a mini regulator at the spray gun and I set it to 10 psi since the Paint Spray Gun Technical data states 1) Air Cap Pressure: < 10 psi and 2) Suggested Air Inlet pressure 29 psi. What's the suggested air inlet pressure? Should I have been painting with the mini regulator set to 29 psi? I thought I was set up correctly because the Omni primer data sheet rrecommends HVLP air pressure of 8-10 psi. Well here is pic, what do you think. I was spraying at about 6 - 8 inches

http://i259.photobucket.com/albums/hh296/sreischel/DSCN0003-1.jpg

Here is several more at this link

http://s259.photobucket.com/albums/hh296/sreischel/

Thanks for the help

[Barry]

29 psi with the trigger pulled...your air was way to low.

Barry

[srsupertrap]

29 psi with the trigger pulled...your air was way to low.

Barry

Well my mistake. So why do they (Spray Gun Mfg & Paint Mfg ) specify the air cap pressure <10 psi when there is no means to measure it?

Sorry about back to back question but I hate shooting myself in the foot.

[Bob K]

They are saying that there gun meets the 10 pound at the air cap regulation by applying 29 pounds to the inlet of the gun. I know that is confusing to someone new to the hobby. As you work on more cars and do more reading it will start to clear up in your mind, but they don’t address the problem for someone new to the game very well. Hay, you won’t make that mistake again, and so it goes, everyone does something for the first time once and then they go on to be more proficient.

Bob K

[Barry]

There is a way to measure it if you want to invest in the diagnostic equipment. The simple way is to follow the mfg instructions given to you....push 29 pounds of air thru the gun and it will produce 8 to 10 pounds at the cap. Always read and follow manufactures instructions...void where prohibited by law...if you experience orange peel longer than four hours seek medical attention....or, in other words...shoot a test panel first to see if you got things set right...

Barry

[srsupertrap]

They are saying that there gun meets the 10 pound at the air cap regulation by applying 29 pounds to the inlet of the gun. I know that is confusing to someone new to the hobby. As you work on more cars and do more reading it will start to clear up in your mind, but they don’t address the problem for someone new to the game very well. Hay, you won’t make that mistake again, and so it goes, everyone does something for the first time once and then they go on to be more proficient.

Bob K

That's for sure, agreed. Can I salvage this peebly mess by wet sanding it down with 320 or 400 and then shooting over it or do I have to break out the paint stripper and strip down to bare metal again?

[BradNes1]

so long as it went on wet enough to get good adhesion you can sand it smooth and reapply your epoxy no problem.

[Clarkey]

I'd use 180 or coarser on that, will take you ages with 320 or 400.
What size is your fluid tip, too small and it can cause these problems also with primers.

[srsupertrap]

I'd use 180 or coarser on that, will take you ages with 320 or 400.
What size is your fluid tip, too small and it can cause these problems also with primers.

I was using a Austuro touch up gun and using the recommended 1.5 tip for primer. It comes with .8 & 1.2 tips for base & clear. It did spray on pretty dry so perhaps the best course is strip and start again

[BradNes1]

that's always the safest but personally I think you would probably be ok just sanding and reapplying some more epoxy. Take some sticky packaging tape and press it down real well onto the epoxy, then give it a good quick yank and if any comes off I would strip it down to metal, if it all stays on there you should be good to go and just flatten it and reshoot. P.S. you can add up to 10 percent urethane reducer or acetone to that epoxy if you still can't get it to lay down smooth.

[All Dry]

From what I see it looks like the materal is too thick for the tip you are using.As long as the adhesion is good I would scuff & level the epoxy a bit and go to your surfacer at this point ,I dont see the need for more epoxy.Myself, I wouldnt use a touch up gun to spray epoxy or primer. Mike

[Clarkey]

I was using a Austuro touch up gun and using the recommended 1.5 tip for primer. It comes with .8 & 1.2 tips for base & clear. It did spray on pretty dry so perhaps the best course is strip and start again

Hmm, 1.5 is small for a primer. Lucky for you, I'm dumb enough to have tried spraying a primer that is supposed to go through a 2.0 with a 1.4. It can be done, it will just be a much slower process. I found that if you move the gun in closer (3-4in) and move slow then you can achieve an acceptable finish. My top tip is to make sure you have really REALLY good lighting while you are spraying, that way you will clearly see if your spray is flowing out smoothly or going into a nasty texture.

[srsupertrap]

Hmm, 1.5 is small for a primer. Lucky for you, I'm dumb enough to have tried spraying a primer that is supposed to go through a 2.0 with a 1.4. It can be done, it will just be a much slower process. I found that if you move the gun in closer (3-4in) and move slow then you can achieve an acceptable finish. My top tip is to make sure you have really REALLY good lighting while you are spraying, that way you will clearly see if your spray is flowing out smoothly or going into a nasty texture.

I believe the touch up gun tips are smaller vs. a conventional HVLP spray gun. From what I have been told most touch up/mini guns come with a 1.0 tip and painters use that successful for spot repairs. I started a thread on the topic a couple of days ago and really didn't reach a definitive answer why but a couple of guys acknowledged the had the same experience.

I will do the tape test later this afternoon and let the results be the determing factor on stripping.

Thanks everyone

[BradNes1]

A 1.5 on a touch up gun is plenty big for that epoxy. I shoot MP170 out of a 1.4 tip in my regular base/clear gun and it works out just fine. Normally I don't reduce it at all but if I'm using it as a sealer prior to paint I will reduce it 10 percent to get it to lay down better. As for not shooting another coat of epoxy after sanding it level you may be ok doing that but I would think that your epoxy coat would be pretty thin by that point and secondly if you want the adhesion benefits of the epoxy PPG reccommends to shoot another coat after sanding if you are out of the 3 day recoat window for this primer. I'd follow the product sheets personally and shoot another coat.