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  #1  
Old 02-01-2016, 10:07 AM
TroyBranch's Avatar
TroyBranch TroyBranch is offline
 
Join Date: Oct 2007
Location: Calgary Alberta Canada
Posts: 457
Default Stewarts Systems Fish Eyes

I know there is a lot of smart people on here and I need some help. I have painted my last airplane with SS and had no trouble. I love the paint. It worked perfectly. Now I am using it again and for some reason my Yellow gets a random fish eye. If I look really close the paint almost falls in places like the beginning of a fish eye. Like something is going wrong as it cures. They start to form around 5 minutes after shooting. I have been trying to solve this with the Stewarts factory for 2 months now.

When it happened I upgraded my filter system by adding a desiccant and a charcoal filter. Basically to eliminate the chance of water contamination. This is the system, as you can see air filtration should be covered.



I also changed my hoses from what I was painting with last time even though there was never an issue then. No change.

I then added a 50ft copper pipe coiled in a barrel of water to cool the air before it goes into the tank. Eliminates the chance of warm air at the gun which could condense at the tip and form water. Cold air filters better as well. Still no change.

This is the example. Around one every square foot.



I decided to shoot the black and got a perfect paint job. I have since painted all my black parts with no issues at all. So I sent the yellow paint to Stewarts. The Canadian distributor got a bit of the issue at a lesser scale when testing and the main branch cannot reproduce it all. They say the paint is fine.

So the last thing I tried was removing the paint filters on the intake side of the booth to see if that was it. (They are the proper sticky back filters) No change.

After keeping this quiet since mid November I really need to reach out to everyone for ideas. The factory cannot figure out what is causing it. I have red coming to me now to test which I shot on the last plane with no issues. I really hope that works. Then I just need to re shoot a few parts changing them to yellow. But why is the yellow doing this?

All testing was done on bar aluminum cleaned with thinner to rule out surface contamination. I live in the country not near a railway and have nothing silicone based in the garage. My gut feel is that maybe there is still some contamination in the air supply but I cannot figure out how. Yellow has the least amount of solids so maybe the slight contamination is only effecting it?

My compressor is a 60gal and at the bottom of the chart for what I should have. 11.5cfm at 90psi. It keeps up fine and worked just fine on the last paint job.

Can you think of something that I may have not tried?
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  #2  
Old 02-01-2016, 10:50 AM
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Bob Martin Bob Martin is offline
 
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Default Fish Eye Eliminator

Not a professional painter here, but I know they make this stuff for a reason.

Thinking it is generic but you might see if SS has it for their product line.
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  #3  
Old 02-01-2016, 11:25 AM
BillL BillL is offline
 
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Location: Central IL
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Default

If you have eliminated the possible surface contamination, then it is in the supply system. I assume you have a final filter at the gun too. I can not read the filter spec on the SATA final system filter, but suggest using as fine as you can get there. 0.1 micron if possible.

The last possibility is coming from something downstream of the final system filter. There are several fittings, regulator and valves there. I don't know the tolerance for such things but the factory should. Hopefully they are concerned about more than if their paint is good. They should be able to tell you the cleanliness specifications for their product, and how it is measured for production operations quality control. Maybe they take the gun and spray it into a sealed container with an absolute filter that is analyzed in a lab.
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  #4  
Old 02-01-2016, 11:29 AM
mbell mbell is offline
 
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If the black comes out fine then there's a problem with Stewart's yellow. Have you tried another batch from them?
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  #5  
Old 02-01-2016, 11:40 AM
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TroyBranch TroyBranch is offline
 
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Location: Calgary Alberta Canada
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Default

Quote:
Originally Posted by BillL View Post
If you have eliminated the possible surface contamination, then it is in the supply system. I assume you have a final filter at the gun too. I can not read the filter spec on the SATA final system filter, but suggest using as fine as you can get there. 0.1 micron if possible.

The last possibility is coming from something downstream of the final system filter. There are several fittings, regulator and valves there. I don't know the tolerance for such things but the factory should. Hopefully they are concerned about more than if their paint is good. They should be able to tell you the cleanliness specifications for their product, and how it is measured for production operations quality control. Maybe they take the gun and spray it into a sealed container with an absolute filter that is analyzed in a lab.
The final Sata Filter is charcoal.
The devilbiss is (Second filter)
Centrifugal Filtering Capacity: 5 micron

Coalescer Filtering Capacity: .01 micron

All fitting are specific to the filters other than the coupler.





Quote:
Originally Posted by mbell View Post
If the black comes out fine then there's a problem with Stewart's yellow. Have you tried another batch from them?
Same issue with two different lots of yellow.
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  #6  
Old 02-01-2016, 12:03 PM
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TroyBranch TroyBranch is offline
 
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Quote:
Originally Posted by BillL View Post
I assume you have a final filter at the gun too.
I tried one at the gun and it did nothing. Everything seems like paint to me, but I have been told different.
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  #7  
Old 02-01-2016, 01:15 PM
BillL BillL is offline
 
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Ahhh - - both charcoal and desiccant can release particles, so, I was thinking the last filter was particle only. The desiccant and charcoal will adsorb gasses and capture aerosols. I would check with the company, but I would have thought the finest filter would be the last one, and it would be a particle filter.

You might want to call these guys and ask, they are experts on filtration.
http://www.driair.com/contact/
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  #8  
Old 02-01-2016, 02:33 PM
Canadian_JOY Canadian_JOY is offline
 
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Location: Ontario, Canada
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Troy - I feel your pain. Not with fisheyes in a topcoat, but with SS epoxy primer. I could not get the stuff to work for me.
A phone call to Dan at Stewart and I learned the challenges I was having were not unheard-of. I didn't have to ask; he immediately offered to replace what he assessed to be defective product.

The new product went on beautifully, but not before I had spent hours and hours sanding off the defective stuff.

Nobody's perfect. Dan certainly did his best to make amends.

Question for you... Which SS paint are you using? How do you like the final gloss of the finish? I may be purchasing our topcoat in the spring in order to have it on hand for application once the weather warms up.
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  #9  
Old 02-01-2016, 03:42 PM
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TroyBranch TroyBranch is offline
 
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Location: Calgary Alberta Canada
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Quote:
Originally Posted by Canadian_JOY View Post

Question for you... Which SS paint are you using? How do you like the final gloss of the finish? I may be purchasing our topcoat in the spring in order to have it on hand for application once the weather warms up.
Ecopoly top Coat. Great shine and almost no smell. It is very forgiving...just don't by yellow.
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  #10  
Old 02-01-2016, 03:48 PM
Mitch757 Mitch757 is offline
 
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Default

I had the same thing happen when painting small parts and, for me, it was in the gun itself. I washed it with acetone, then Dawn, then 91% rubbing alcohol.

Finally, I got a good application on my parts. I don't know where the contamination came form since the gun worked well in the past.
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