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Need help with paint issue


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#1 scalemodelworld

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Posted 16 March 2013 - 09:32 PM

I've started building the Ghostbusters Ectomobile (from the original movie), and something weird has happened to the paint, as you can see below. This has never happened to me before, so I don't know WHY it happened, or how to fix it. I'm assuming I can just sand it back and repaint, but I want to make sure the problem doesn't re-occur. Any advice on the cause and/or corrective action would be greatly appreciated.

 

To help with the diagnosis, the body was primed with Tamiya grey primer, and then coated with TWO mist coats of Tamiya Pure White (acrylic) which went on perfectly. It was when I applied a wet coat that the issue happened. I painted outside using a rattle can, where the weather was warm (not hot) but maybe a bit humid.

 

Please ignore the fact that I put white paint on grey primer.

 

The issue is just above the wheel skirt:            Here the problem is on the top right of the hood and in the panel line:

Attached File  Paint 1.JPG   107.41KB   84 downloads                      Attached File  Paint 2.JPG   91.57KB   83 downloads

 

 

 



#2 moparmagiclives

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Posted 17 March 2013 - 01:24 AM

I would have to guess there was something on the body or in the seams. Water or oil of some kind. The fender looks like moisture trapped under the paint but the hood looks like fish eye.

Edited by moparmagiclives, 17 March 2013 - 05:51 AM.


#3 trogdor

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Posted 17 March 2013 - 01:40 AM

Did you wash and completely dry the body first, before the primer ?



#4 Blown03SVT

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Posted 17 March 2013 - 04:01 AM

Did you recoat in the proper window of time? If it is not fish eyes it actually looks like solvent popping to me.



#5 DPNM

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Posted 17 March 2013 - 07:56 AM

I am not familiar with the specific paint you used but it looks like some type of a contamination issue. Did you sand the body first? If yes, did you sand the hood seam? If you washed it then dried it with a rag or towel, the rag or towel may have had something on it.



#6 Skip

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Posted 17 March 2013 - 10:46 AM

Looks like solvent pop.



#7 MAGNUM4342

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Posted 17 March 2013 - 11:10 AM

As far as white over grey primer. I think it gives it a better "ghostly" look to the paint job. If it was overly humid I would say that caused the wet coat to solvent pop like that. You can purple pond it, or if the problem is located in just these areas you can wet sand it down and feather it in then re-coat. I've found when it gets humid around here that i'm better off with several mist coats and a good wet sand and buff than trying to lay that final glassy wet coat. For some reason the moisture in the air causes the paint to go anywhere from badly fisheyed to what you have there. Anyway that's been my experience. Sadly during the summer here I get very few days that aren't humid.



#8 scalemodelworld

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Posted 17 March 2013 - 01:43 PM

Thanks for the help everyone. To answer the questions:

 

The primer was applied almost a week before the colour, so it shouldn't be an issue there. I applied two mist coats, waiting until the paint was a little bit beyond touch-dry between coats. Not sure if that's the perfect timing, but it's my usual process and I've never had trouble before.

 

The body was wet-sanded between the first colour coat and full wet coat. It was then rinsed, shaken dry and then air dried. I'm thinking that the body maybe wasn't 100% dry when I applied more colour.

 

I'm thinking that my best solution is to sand it all back and recoat the whole body, rather than just try to fix the small areas. Can anyone suggest a better option?



#9 scalemodelworld

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Posted 18 March 2013 - 12:36 PM

Geez, I feel like a newb after reading all those posts. Maybe I'm just lucky, never having had any real problems with paint before. I've never heard of "purple pond" or fish eye, although after some quick research, I've now learned.

 

I'm going to try sanding the body and re-spraying, rather than purple ponding. I've used brake fluid to remove paint before and it works a treat, but as I keep saying, everything in Australia costs a fortune. Paints are $15 each, primer is $17 (for the bigger can), so if I purple pond it, I'm looking at another $47-ish just to repaint. This is actually the main reason I'm looking at getting an airbrush. I think I'll be saving money in the long run.



#10 MAGNUM4342

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Posted 18 March 2013 - 12:44 PM

An airbrush and good compressor will save you a lot in the long run. Just make sure to keep that airbrush clean and it will serve you well for some time.



#11 Modelbuilder Mark

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Posted 18 March 2013 - 04:49 PM

"Purple Pond" simlpy refers to soaking the body/parts in "Purple Power" or Castrol Supoer Clean to strip the paint. Great stuff.

 

Fisheye is where the paint "pulls away" or refuses to settle down in an area due to contaminants such as sillicon, oil, etc. The resulting spot from the paint not adhering looks a little like a fishes eye.