contamination?

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contamination?

Post  Kevster on Sat 05 May 2012, 8:10 am

Hi everyone,

I seem to be getting comtamination of some sort on the parts im painting, i spray the paint on and I keep getting small spots( about 2 mm in diameter) where the wet paint just pulls away in
a little circle and you can see the previous coat.
What do you use for wiping over the part you are about to paint?
I have used meths also white spirit but still seem to be getting these annoying little circles.
there are only one or two of them appearing but its spoiling the job.
Any ideas anyone?

thanks

Kev

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Re: contamination?

Post  lynnr on Sat 05 May 2012, 8:37 am

Use paint prewipe as white spirit is petroleum based

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Re: contamination?

Post  Kevster on Sat 05 May 2012, 8:46 am

ah thanks Lynn maybe thats where im going wrong then?

I have tried with and without white spirit but still get them



I will get some pre wipe and give that a try.

Thanks

Kev

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Re: contamination?

Post  Robfishman on Sat 05 May 2012, 11:48 am

Are you able to post a picture of the problem, sounds like the same problem I had which was down to water in the lines. I had the same effect, and took a while to find the cause.

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Re: contamination?

Post  lynnr on Sat 05 May 2012, 12:30 pm

To test. Clean an area with your usuall method. Then pore clean boiled and cooled water on an see if you get a film or beading. You want film as that demonstrates paint compatable clean. I.e no surface tension reducers present The thinners and white spirits are not evaporators so will leave a residue.

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Re: contamination?

Post  Kevster on Sat 05 May 2012, 1:26 pm

I thought it might be oil or water in the line as my little compressor was quite old so I replaced it with a new oil free one
and upgraded the water trap and filters in the line but it still seems to be there .

im using all craftmaster paint and thinners,it only seems to show up with the top coat,primer and undercoat seem to go on fine.

its just like there is a little spot of contamination and the paint runs away from it and leaves a little circle unpainted as it flows out.

Hopefully the panel wipe wil do the trick.

thanks

Kev

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Re: contamination?

Post  Weston on Mon 07 May 2012, 11:16 pm

Hi Kev,

This problem is known as fish eyeing, or fish eyes.

It can be a common occurrence in painting, it really does depend on what solvents or silicones the material has been near before painting. Ie have you been in the workshop near your parts spraying any silicone based sprays? the smallest amount on the surface will have a dramatic effect. In worst case you are going to have to go back to bare metal and start again to remove the contaminant.

Click Here, scroll halfway down

Hope this helps

Ryan

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Re: contamination?

Post  Adam Brown on Tue 08 May 2012, 5:05 am

A belated reply to the original post. We don't really recommend the use of panel wipes as they can (as you may be experiencing) cause all sorts of problems if the solvent in them isn't compatible with our own

Bare steel should always be degreased and cleaned, in my experience synthetic thinners do the job. After that a rub down between coats and a wipe over with a tack cloth. As the name suggests its a tacky piece of cloth and it picks up all the dust and residue on the surface without leaving any nasty solvents or other contaminets behind

I'd avoid pouring water on it if possible

Hope this helps, feel free to call me at the office if you have any other questions I can help with

Adam
Craftmaster

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Re: contamination?

Post  Kevster on Tue 08 May 2012, 7:31 am

Got myself some proper panel wipe and it does seem to have cured the problem on the couple of bits I have tested with.

fingers crossed my problem is cured !

thanks for all your replies

Kev

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cleaning silicone off paint

Post  Mclarenman on Tue 17 Jul 2012, 2:22 pm

I have had reasonable results washing down with white vinegar and then manista hand cleaner to remove silicone contamination from full size engines. Many engines have had years of being sprayed with all manner of polishes and silicone almost always shows its self.
I rub back the paint with 240 grit wet n dry then wash with the above. Id say it gives a 95% reduction in fish eyes. I never use panel wipes after watching the sign writing on a road locos canopy start to wrinkle, and that was after the lettering had been on for a week.

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Re: contamination?

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