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  #1  
Old 01-28-2012, 11:19 AM
tomcostanza tomcostanza is offline
 
Join Date: Jul 2005
Posts: 292
Default Paint 1 : Mind 0

I'm sending this before I go completely mad.

The photo shows one example (there are many more) of what I can only describe as fish-eye contamination while trying to paint my instrument panel. This is Eastwood epoxy primer, but I have seen it with Akzo also. I have tried different paint, different guns, different compressors different metal. The only thing that is common is the location (my garage), and the season(temp = mid 40s outside high 50s inside). I etched the metal and alodined it. Later scrubbed the bejesus out of it with Scotchbrite after stripping the paint for about the 3rd time. I'm sure any alodine conversion went out with the scrubbing. Then washed it with Dawn dish detergent and rinsed with enough water to flood Texas.

If this were a woodworking project, I would assume silicone contamination and coat with shellac before varnishing. So I used some rattle can of self-etching primer, and, surprise, no fish-eye. Great. Then I sprayed the epoxy primer over the rattle can primer and took this picture.



I'm in the 6th year of a 3 year project, have primed the entire interior, and have never seen this before. I have moisture traps at the compressor and at the gun. I have never used an oiler, and as I said, I have used 2 different compressors with 2 different hoses.

If anyone can help me solve this problem, I will be forever in your debt.

Thanks and regards.
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  #2  
Old 01-28-2012, 11:27 AM
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Mike S Mike S is offline
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 16,095
Default Looks like water or oil in the air line??

Do you have a water separator in your air line??

Are you using the same air line you use for air tools?? Does it have a tool oiler?

Have you drained the air tank lately?

You can buy small desiccant units that screw into the paint gun, and the hose hooks up to them, might help. Automotive paint supply houses have them.

Here are a couple of them.

http://www.paintsprayersplus.com/pro...-W-Refill.html

http://www.ecompressedair.com/air-dr...nt-of-use.aspx
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Last edited by Mike S : 01-28-2012 at 11:32 AM.
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  #3  
Old 01-28-2012, 11:46 AM
Bob Axsom Bob Axsom is offline
 
Join Date: Mar 2005
Posts: 5,685
Default No painter claim here but I have experienced the problem

I'm sure there are technical solutions but when it happened to me I made a point of not holding my gun directly over the part being painted and spraying more horizontally to the part. That fixed my problem.

Bob Axsom
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  #4  
Old 01-28-2012, 11:52 AM
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9GT 9GT is offline
 
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Location: Southern Michigan
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Default

Another trick is to coil up a 50' air hose, attach it to your compressor outlet. Place the rest of the hose in a 50 qt. cooler and then fill it with ice on top of the coiled hose and attach your airgun hose to the coiled hose, out to your gun fitted with a desiccant filter. The humidity in the compressor air will cool and condense in the coiled hose and the filter will catch anything that might make it out. A poor mans air drier. Is it possible that your primer is not contaminated?
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  #5  
Old 01-28-2012, 12:18 PM
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frankh frankh is offline
 
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Location: Corvallis Oregon
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Default

I'm betting oil.

Its amazing the slightest contamination of oil will do this. I did use an oiler on an old hose about 10 years ago..but did most of my build without an oiler..Surely after passing all that air through the hose it can't possibly have any oil contamination..WRONG!.. Changed for brand new hoses and problem dissappeared.

Now, do you have an oil free air compressor? If not I bet you have a little bit of cylinder wear and getting some carry over.

As long as you are sure there is no water in the lines thats all it can be.

You did degrease the panel before spraying I assume?
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  #6  
Old 01-28-2012, 12:23 PM
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rocketbob rocketbob is offline
 
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Location: 8I3
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Default

What did you wipe it down with before painting?
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  #7  
Old 01-28-2012, 12:35 PM
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John Clark John Clark is offline
 
Join Date: May 2005
Location: Santa Barbara, CA
Posts: 1,324
Default Silicone

Silicone lubricants are a big problem around paint. This can be in the form of a "spray lube" being used almost anywhere in your shop. Trust me, the stuff will float around. The other silicone contamination problem is dryer sheets, yup, the tissue sheets put in the dryer to make the fabrics "soft". If you dry some shop towels in the same dryer, even without adding a new "sheet', and you use the rag to to wipe the area to be painted you will get the results in the photo. There are a couple of things that help. Automotive paint stores have anti-fisheye additives that can be added to the paint if you are using a spray gun. There are also cleaning agents to remove the contamination, but I have had marginal success with them.

John Clark ATP, CFI
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  #8  
Old 01-28-2012, 01:41 PM
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videobobk videobobk is offline
 
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Location: Near Scipio, in Southern Indiana
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Default

I hate to say it for fear of sounding anti-DIY, but painting is one area I leave to the pros. Not that it can't be done, but sanding off $100/qt paint just isn't fun. If problems persist, this might be an avenue to consider...

Bob
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  #9  
Old 01-28-2012, 02:12 PM
tomcostanza tomcostanza is offline
 
Join Date: Jul 2005
Posts: 292
Default

Quote:
Do you have a water separator in your air line??
One at the compressor. One at the gun.

Quote:
Are you using the same air line you use for air tools??
Yes

Quote:
Does it have a tool oiler?
No, I have never had a tool oiler, so the hose has only had air in it.

Quote:
Have you drained the air tank lately?
After each use

Quote:
Now, do you have an oil free air compressor? If not I bet you have a little bit of cylinder wear and getting some carry over.
Tried 2 different compressors. One oil-free, one not.

Quote:
As long as you are sure there is no water in the lines thats all it can be.

You did degrease the panel before spraying I assume?
First with acetone, finally with soap (Dawn dish detergent) & water

Quote:
What did you wipe it down with before painting?
First with acetone, finally with soap (Dawn dish detergent) & water. Dried with new paper towel, blew off with compressed air, and let sit for 30 minutes.

Quote:
Automotive paint stores have anti-fisheye additives that can be added to the paint if you are using a spray gun.
This sounds like it might work. Yes I am using a spray gun. Are there compatibility issues? Do I need to get the additive from the same manufacturer that makes the paint, or will any additive work?

Quote:
I'm sure there are technical solutions but when it happened to me I made a point of not holding my gun directly over the part being painted and spraying more horizontally to the part. That fixed my problem.
Sometimes the simplest solutions are the best. The panel was horizontal when I sprayed it, and I did have the gun directly over it. I'll try this fix first.

Thanks to all. If anyone else has any ideas, I'm all ears.
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  #10  
Old 01-28-2012, 02:13 PM
jrs14855 jrs14855 is offline
 
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Location: Lake Havasu City AZ
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Default paint

I scuff the bare metal with fine scotchbrite, no other treatment until primer. I wipe down bare metal with Dupont 3939s. PPG self etching primer, top coat it with high build primer if necessary. No rags, no soap. fresh paper towel for all wipe down, there are also specialty wipers available from auto paint stores.
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