Huge dry overspray problem with Sikkens ColorBuild as Surfacer

[Tom and Vipers]

I have a mess on my hands.

I have another thread that went into problems with my air supply to the gun. Well that is solved.

Now I just laid on 2 coats and here is what happened:

First, I simply could not get a uniform fan pattern (i.e. a constant thickness verical stripe), instead the best I could do was a heavy center ellipse.

Tried all combinations of pressure, air setting, and paint setting.

So I picked about a 9-10" fan and started primering.

The first few passes went on nicely.

But each pass left a field of dry overspay granules where the next pass would be.

So I tried to keep things wet and "melt" the dry spray in.

The only problem was that with each pass I had to lay down more primer to keep it wet which only produced more dry spray which required even more primer on the next pass to keep it wet.

I had started working from the back of the hood and by the time I made it to the center, I shudder to think how thick I had applied it (if someone told me I put .032" on it, it wouldn't surprise me at all.)

So now I sprayed the major portion of my cup on 1/2 the hood and just tried to cover the remaining 1/2.

Since I am on a 3 week "vacation" trying to get results, I said:

SCREW IT, I'm putting another coat on.

I focused on the other 1/2 of the hood whcih contained the louvers and finished the other 1/2 with less of an indicent because I was now aware that it wouldn't be possible to put a nice wet coat on.

What concernes me is that on some places of the hood, I put massive amounts of paint to make the crumbly #80 grit dry crumbs wet.

Ohhhhhhhh, the days of solvents.........

Any ideas? (let me guess, you're NOT supposed to put it on wet, right???)
Tom

PS. I can get fantastic results with that DupliColor High Build Primer out of the gun. No dry overspray. Nice wet application. Nice super high build. HaHa

 

[HP]

You're charting new territory with 'latex' - the only thing that comes to mind is that you might need to back off the amount of paint coming from the gun, and/or keep the gun closer to the work. Nothing more stressful as trying to decide 'go/no-go', when you have a bunch of paint mixed and it's not going down right.

 

[Tom and Vipers]

Some pics.

Do not click on them, they are hideous and may lead to years of sleepless nights!

dry spray 1

dry spray 2

Looks like I sprayed ceilings in FL homes 30 years ago, eh?

Fit to be Tied,
Tom

 

[Tom and Vipers]

"Problem" "Solved" (!)

Showed paint shop the photos and said there was NO WAY it could be anything other than a bad gun, so I returned the gun and they gave me an IWATA primer gun.

Now we enter the Twilight Zone:

1) TRY OUT THE NEW GUN.

I get the gun home, get ready to paint, hook it up, and.... ...and I decide just to put the 3M bag cup on it just to see it collapse the bag.

The gun makes a random noise - two different turbulent "hisses" - and the bag does not collapse. In fact, you can see the bag pulsate in sync with the changing between the 2 audible states.

This gun is spec'd to produce 10psi @ cap w/20psi @ inlet. If you turned pressure up to 30-40psi at the gun, the sound of one of the states simply went away and only then would the bag collapse.

So I figure I have a bad gun.

2) TAKE THE GUN BACK:

I take the gun back to the paint shop and it workes perfectly with his setup. Nice uniform sound, ***** the bag down.

We figure that maybe I had too high a line pressure leading up to the bleeder valve at the gun. So I figure all I have to do is set the line pressure to the proper level at the filter/regulator and I will get the gun to behave properly.

3) TRY THE NEW GUN AGAIN:

I hook up the gun, reduce the pressure and it MAKES THE RANDOM NOISE AGAIN !!!!!

4) WHAT WAS DIFFERENT BETWEEN THE STORE AND MY SETUP:

At the store, he rotated my needle valve 180 degrees. Since this valve has the inlet offset from the outleg, perhaps there was a different swirl. I put the needle valve back 180 deg and still makes the noise.

At the store, he used the "auto body coupling" rather than the "industrial coupling" that is everywhere to be found - especially in cheap, Chinese form. I figured maybe it was the coupling so I connnected the gun directly to the hose with a 1/4" pipe T in which I put a pressure gauge.

I set the line pressure low so I don't overpressure the gun, hook it up and pull the trigger....

Immediately I heard the sound again (ugh) and also immediately noticed I was at very low inlet pressure - around 10 psi. Just a few seconds at the most after I pulled the trigger for the first time, I adjusted the regulator up to get 20psi at the gun. Now either just before I did this, or as I did this, it was as if some particle blew out of the gun and the noise went completely away.

Perfect sound, perfect siphoning.

While I suspected it was the coupling, I had to realize that for a few seconds it still make the bad noise when plumbed directly.

So I put the old industrial coupling back to my origianl rigging which gave me the trouble in the first place and guess what? NO NOISE! The problem was now completely gone and I have no idea what caused it and how it was corrected.

I put 3 coats on the hood without incident - the IWATA gun could make a nice, uniform 14" pattern if you were that crazy - at 12psi! I was putting the primer on with very low supply pressure and I was making so little spray "noise" that my friend didn't even realize I was primering.

So I am back on track with the project.

However, I am wondering if there was anything ever wrong with my setup. I suspect not because this IWATA did the noise at a completely different area in the shop - different coupler, plumging etc. I still can't explain why the gun worked OK at the store (his compressor was the crapiest thing you could imagine - it literlaly sounded like the pulleys were going to fall off. It was something like a 3/4hp with NO SHUTOFF CONROLLER!)

Of course, was any of this contributing to the poor performance of the Sharpe I originally returned? Who can say.

I would sure hate to be responsible for the fuel pump on the Space Shuttle main engine and have some nonsense like this occur. It would be real tough to say everything is OK and good to go.

Onward,
Tom