Contamination in single stage

[Dan Trimbach]

I’m spraying panel by panel and started with the hood. I spayed a seal coat of spi epoxy reduced 1:1:1 It looked really good.

I waited 6 hours and started spraying the hood. Right when I started a huge wind came in. Probably around 15 mph. I was already committed so I finished spraying the first coat is Spi ss black.

I definitely got some trash in it and some bad orange peal. But I had already mixed up enough paint for two more coats so I sprayed them 30 min apart.

It looked ok from about 10 ft.

I started to sand it out with 600 grit and noticed little pin holes that just won’t sand out. I had to go down to 400 grit to get most of them out. I then hit it with some more 600 to take out the scratches.

I’m still seeing some of the defects. But I’m now a little worried that I’ll have to strip the whole panel. These seem like they aren’t trash as much as some sort of contamination.

They don’t seem that deep. If I hit it with a few more coats of single stage will they bury or will they come through like a fish eye?

 

[Barry]

Dont bury the defects sand out with 600 or 800 wet, make it perfect, then let's decide if we seal or start with ss again.

 

[Dan Trimbach]

Thanks Barry.

I got them all out with the 600
How do we deturmine if I need to seal coat again?

 

[Barry]

It looks like ready to paint.
Unless, for some reason, you think it needs to be sealed.

 

[Dan Trimbach]

I guess I’m doing something wrong.
I sprayed it again and I thought everything was going fine. Then I got what I assume is solvent pop.

 

[Barry]

If it was not something that shot of of gun then its water but sure looks funky, this is a strange one.

 

[Jim C]

yeah solvent pop doesnt look like that. solvent pop is much finer and very even across a panel. it can almost look like a cloudy spot or micro fine dust on the paint. that looks like dirt in the air, on the panel or something coming from the gun.

 

[Raymond_B]

I am not a professional by any means, but besides the weird bumps doesn't it look like the paint was put on very very heavy? Could that contribute?

 

[dhutton01]

What compressor and air filtration etc are you using?

Don

 

[crashtech]

Looks like water to me.

 

[elwood]

Dirt from air hose?

 

[crashtech]

The reason I think it's water is that the defects look spherical shapes under the paint. Photos over the Internet is a terrible way to try to diagnose something, though.

 

[Dan Trimbach]

I dont think it was dirt. It appeared to be bubbles.
it happen on the third coat. I sprayed one, waited 30 min, then a second coat followed immediately by a third coat thathad 20%retarder added.

I’m thinking it was water. It is very dry here in Colorado so I didn’t think it would be a problem.
I just have one of the cheap harbor freight air filters.

For my next attempt, I think I’m going to try an in line filter right before the gun. im also going to try to move a little faster and try to spray thinner instead of laying it on as thick.

I’ll also just skip the retarder and go the full 30 min flash time on the last coat.

 

[Dan Trimbach]

Also out of curiosity.
I didn’t run into this while spraying epoxy or 2k primer. Does water show effect single stage more?
just wondering why this is all of the sudden a problem for me.

 

[sprint_9]

it happen on the third coat. I sprayed one, waited 30 min, then a second coat followed immediately by a third coat thathad 20%retarder added.

The answer to at least most of your problems is skipping the 30 min flash time between the 2nd and 3rd coat. You cant add retarder and just skip the flash time between coats, retarder helps it flow out in high heat/humidity, its not a substitute for flash time.

Here is a good thread on retarder and its uses http://www.spiuserforum.com/index.php?threads/explain-retarder-to-me.7418/

 

[dhutton01]

Also out of curiosity.
I didn’t run into this while spraying epoxy or 2k primer. Does water show effect single stage more?
just wondering why this is all of the sudden a problem for me.

How often are you draining your compressor tank? What size is the tank? What horsepower?

Don

 

[BallsOutPerformance]

Which harbor freight filter are you using?

 

[crashtech]

Back to back coats? And 20% retarder? Am I reading that right?

 

[Dan Trimbach]

Well I didn’t just come up with that on my own.

Flow coating. What's your method?

As a preface I have been flow coating all of my personal projects and the ocassional customer project for a while now. Maybe the way I do it is just how it is but just wondering if anyone else out there has any pointers, tricks, time savers on doing it. My method is to spray base then wait...

www.spiuserforum.com

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Barry
Paint Fanatic
Staff member
Jun 12, 2015

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• #5

Here is something interesting, I plan to try.
I have heard from a number of shops (7-10), now and all swear you have never seen anything like it.

They do 3 or 4 normal coats waiting 30 minutes between coats, then as soon as done with 3rd- 4th coat they mix more clear and I have been told from some they add 30% retarder and some they add 50% and right away put a 5th coat on.
Makes sense to me but have not tried it myself yet.

This is why I love the tech line, learn something everyday!

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I wasn’t brave enough to do 30%

 

[Dan Trimbach]

I’m using a 7hp Spl 10.3cfm@90psi 60 gal air compressor and a harbor freight 3/8” air filter. Item 68230

I’m using a 3m accuspray gun with a 1.4 tip

I drain it about once a week and usually there is very little water on there.