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Paint 1 : Mind 0

tomcostanza

Well Known Member
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.

107ung2.jpg


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.
 
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/product/ACC-42/Disposable-In-Line-Desiccant-Air-Dryer-W-Refill.html

http://www.ecompressedair.com/air-dryers/point-of-use/ds20-point-of-use.aspx
 
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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
 
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?
 
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?
 
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
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
 
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
 
Do you have a water separator in your air line??
One at the compressor. One at the gun.

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

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

Have you drained the air tank lately?
After each use

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.

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

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.

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?

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.
 
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.
 
You say you used two different compressors..But did you use the same air hose on the oil lubed compressor then used that SAME hose on the oil free compressor?

If you were getting oil carryover in the into the air hose, then that could easily be enough to spoil the paint, even when using the oil free compressor.

Frank
 
I recommend laying down a light tack coat first followed by normal coats. Make sure it is light (it should not be opaque) and wait for it to get very sticky. I had the same issues and this worked for me.
 
First get a new air hose
Next spray 1/4 cup of lacquer thinner through the gun to clean it till only air comes out prior to each use
Then wipe the piece to be painted with prep-sol or a wax and grease remover
Use two cloths one wet and one to dry it quickly,do not let it air dry, acetone is not recommended to clean with.
Last use lint free towels and use only air to blow any dust that may have just settled on the part.
Purchase disposable air filter cartrages that screw on to the gun as a last resort

Try again
This should solve your issues
 
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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.

Was that air passed through an oil/water filter at the spray nozzle? If not, you probably just blew crud all over your nice clean metal.
 
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Syringe rubber?

Hello

I had the same in the beginning of the project. I was using a syringe with a rubbertip to get the paint and hardener out of the can.

These rubber had a lubricant that created "fisheye".

Only use a syringe with a plastic seal/tip.

Good luck,

Dominik
 
Mist tack then coat

When I was working with Stewart Systems paint, I has similar issues. Dust coat, pause, then full coat worked to reduce the issue 99% over bare/etched or alodines alum.

I'm betting air/oil though. I use a dessicant air dryer, dryer at the gun, and an ounce or two of solvent through the gun before loading paint.

I have suffered the dryer sheet nightmare.

Finding root cause would be nice. But sometimes finding what works doesn't require root cause. Painting is like that often.

Rick 90432
 
How are you heating your shop?

There was a post not too long ago that noted contamination from a non-electric heater (can't remember if it was propane or kerosene). The poster heated the space, shut off and removed the heater for safety reasons, then painted. However, the heater left combustion bi-products in the air that affected the paint.
 
more .02 ideas

I'll try not to repeat others comments;

I've done the same looking paint jobs, so don't feel TOO bad.

the fisheyes look like water spits to me, so I'd look at that real close. If it's cool and humid out, then you are potentially condensing a LOT of moisture in the compressor process.

if you are doing trial & error testing, take the Dawn soap out of the equation.....never seen that at a professional paint shop, have you?

also, use a new tack cloth with NO pressure to dust the surface just prior to shooting colour, or a towel moistened with prep-sol.
do NOT blow off with air....thus taking contaminated air/hose out of the equation. ( why would you want that dust airborne anyway?..unless you are in a real hi-flow spray booth)
shoot some colour on another panel right beside the one you are doing, even a scrap of metal from under your bench; with no prep. If there's fish-eye on it, then it's not your prep, it's the gun or air.
good luck, and don't get frustrated, after all, you are an 'EXPERIMENTER'.! :)
 
How are you heating your shop?

There was a post not too long ago that noted contamination from a non-electric heater (can't remember if it was propane or kerosene). The poster heated the space, shut off and removed the heater for safety reasons, then painted. However, the heater left combustion bi-products in the air that affected the paint.

My painter worked in a hangar at Riverside and almost went into panic mode when a tubine or jet taxied by - they rushed to fully close all of the hangar doors. He said the burnt kerosene by-products would ruin a wet paint finish
 
my guess is the surface was dirty before you ever pointed a paint gun at it.

that looks exactly like what happens when you let pre-cleaner set on a part with out wiping it dry.

It will happen to ALL types of paint and/or primer.
Wipe on your cleaner, then with a dry cloth (paper lint free) wipe it completely dry with no delay. Not sure if its clean?? Look at the cloth each time you wipe it, if you see dirt in the shape of your hand, its not clean. You should not see ANY dirt, stain, color, etc etc on the cloth.
 
Don't use dawn

I'm in the middle of painting my RV-6. In my research of the process I found that you should never use liquid detergent. Is the dawn you're using liquid? My process for the exterior of the aircraft is to wash with powder Tide and maroon scotchbrite. Rinse thoroughly and check for a smooth water break (no beading). Spray with epoxy primer, base coat and then clear coat. The only time I got fish eyes is when I've had to sand and re-clear coat. The fix for that was to wipe with mineral spirits followed by a damp clean towl and plain water. Granted I'm doing this in AZ where humitity is low but the temperatures have been from 50 F to 85 F.
 
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I agree with Mike S. on the need for a desiccant type filter immediately before the gun, that solved my similiar issue. After acid etching, I would suggest you simply alodine, rinse with water, let dry, and then paint. The small plastic desiccant dryer/filters can be reused by placing them in a toaster oven, on low, for several hours, as they are kind of expensive in my opinion.
 
alodine wont work unless you acid etch the aluminum first.. other wise all you have done is trap "gunk" under the alodine.. which then becomes dusty **** and falls off
 
Syringe rubber?
Hello

I had the same in the beginning of the project. I was using a syringe with a rubbertip to get the paint and hardener out of the can.

These rubber had a lubricant that created "fisheye".

Only use a syringe with a plastic seal/tip.

Good luck,

Dominik

Dominik, you might have won. I am doing this, and this might be why it has only happened recently. I may have not used a syringe previously. I previously had been mixing much larger batches of paint. Now I'm down to mixing only a few ounces at a time. I'll report back on this thread in the next few days.

Patient: Doctor, it hurts when I do this...
Doctor: Don't do that!
 
Respirator drops?

One more possible cause to consider/eliminate...I recently saw similar on my parts when painting in more humid, cooler temps. It was condensation (from my breath) misting out the exhaust port on the respirator.
 
Dry nitrogen

I have used compressed nitrogen when the available shop air was suspect. Works great for small jobs.
 
In my limited but successful painting projects I found a few things that seem to always work. First, I use an HVLP paint system which virtually eliminates any moisture from the process. My second rule is to never use any prep other than sandpaper followed by blowing any dust off with the HVLP filtered system. If I need to go further in the cleaning process, I use an approved tack cloth. Good Luck.
Woodman
 
Many thanks to all for the good advice. I repainted with the epoxy primer. Eliminated the syringe from the equation, and no fish-eye (special thanks to Dominik). While I'm not ready to claim victory, I'm optimistic.
 
Glad it helped you!

Hello Tom

Hopefully you got it!

I just remembered when I saw your pictures ... I had exactly the same, sorted out all the known stuff, but could not fix it. Then once when i was mixing up an additional "testbatch" ... I was looking at that syringe ... I took a new one and they look even more like some kind of "wet" when I open the plastik ... I had before allready good batches, but from time to time the bad one came back! Always when I was using a new syringe. After a while, you will get less and less fisheye, untill you take an new syringe again.

So I throwed away all the rubbertip syringe and banned them from building place!

Best regards, Dominik
 
Should have read this thread yesterday

Today I shot the 2nd batch of primer and fish eyes everywhere.

Guess what was different?

Yup - I used a big syringe to pull paint.

Sheesh - thanks Dominik I know what I will change first!
 
It doesn't take much to contaminate an otherwise perfect paint job. Some years ago one of the major car manufacturers was having a big problem with their paint line and finally figured out the contaminates were coming from antiperspirant from the workers.
 
Mold release used in molding the rubber part of the syringe is silicone!!!!!
I had the same problem and solved it with using dental cups to measure out the paint and hardner. Of course most every paint system will sell you "fish eye" remover...expensive. Best to keep everything clean and dry.:)
Dave (Swift Driver)
 
Chemicals!

Hi All:

I use DuPont 259S fisheye remover in every batch of primer and paint I mix up. Dunno where the contaminate comes from, but I have seen it too. The 259S fixes that problem! Couple drops in a 24oz mixed batch and I'm good to go.

As a Chemical Engineer friend of mine says: "Better living through modern chemistry!"

Carry on!
Mark
 
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