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What Should a Mist Coat Look Like?

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  • Member since
    March, 2016
What Should a Mist Coat Look Like?
Posted by Haptesthai on Tuesday, January 31, 2017 8:55 AM

Hello;

 

I am trying to shoot some Gunze H309 Paint thinned with my mixture of thinner (1/3 IPA, 2/3 distilled water, drops of flow improver&retarder). However, I am not happy with what I am getting. 

 

I cannot get a "mist" coat. If I try to get a thin, translucent coat, my airbrush gives me tiny drops/spots, instead of a uniform layer. So, I do a heavy coat, but this time, when the paint dries, I find some large "holes" in the paint. It looks like as if it did not get any paint.

 

Any ideas?

  • Member since
    April, 2006
  • From: ON, Canada
Posted by jgeratic on Tuesday, January 31, 2017 1:56 PM

Mist coat, you should still see the underlying colour.   You are correct to thin the paint so you can slowly build up the paint layer.

Assuming all the ingredients are compatable and not separating your paint in the airbrush, I'd suggest to practice on a scrap surface, even paper will do.  Other things to try is decrease the psi,  remove the needle protection crown to avoid build up of paint inside - that can spit out in clumps.  Make sure the needle point isn't damaged, as that too can cause spitting.  Also be certain the moisture trap is working, and no water is entering the airbrush proper.

regards,

Jack

  • Member since
    March, 2016
Posted by Haptesthai on Tuesday, January 31, 2017 2:18 PM

jgeratic

Mist coat, you should still see the underlying colour.   You are correct to thin the paint so you can slowly build up the paint layer.

Assuming all the ingredients are compatable and not separating your paint in the airbrush, I'd suggest to practice on a scrap surface, even paper will do.  Other things to try is decrease the psi,  remove the needle protection crown to avoid build up of paint inside - that can spit out in clumps.  Make sure the needle point isn't damaged, as that too can cause spitting.  Also be certain the moisture trap is working, and no water is entering the airbrush proper.

regards,

Jack

 

 

Thanks for the reply. Am I supposed to be able to see hundreds of very little spots with a light coat? Because it is what I get, a translucent coat with hundreds of dots. (does not look like spitting)

 

 

  • Member since
    April, 2006
  • From: ON, Canada
Posted by jgeratic on Tuesday, January 31, 2017 3:13 PM

It depends a lot on the two colours - at extremes such as going white on black, then yes you could very well see dots.   You might have to introduce the original base colour into the airbrush mix to alleviate that problem.  Also, use a wide coverage spray - but I have a feeling maybe the water is causing the droplets to form. 

Might help to post a pic of what you are ending up with.

regards,

Jack

  • Member since
    January, 2009
  • From: hamburg michigan
Posted by fermis on Tuesday, January 31, 2017 3:37 PM

Another thought...rather than thinning so much, you could mix the paint with clear flat (if it's the same sort..ei, acrylic...I'm assuming you're using acrylic paint???). This allows you to spray at a normal "thin-ness". May be worth a shot on a testbed. I have zero experience with acrylics, so I can't promise anything! I do mix enamel paint with clear flat lacquer all the time. Mainly, I pretty much just "tint" the clear to spray over decals to tone em down/weather em a bit. I works great, and the results are better than trying to do the same thing with very thin paint(which give me the tiny dots you describe).

  • Member since
    April, 2006
  • From: ON, Canada
Posted by jgeratic on Tuesday, January 31, 2017 4:26 PM

fermis has a good idea too.

Acrylics by nature do dry quick, and though you have added retardner, the water likely negates a lot of that. 

regards,

Jack

  • Member since
    August, 2005
  • From: Sydney, Australia
Posted by Phil_H on Tuesday, January 31, 2017 6:20 PM

Personally, I wouldn't use water as a thinner, even though the Gunze label says you can.

Water will increase the surface tension causing (1) lesser atomisation of the paint, which results in larger droplets in the spray pattern, and (2) a tendency for the paint on the surface to bead and "pull" into pools, which may be exacerbated by surface contamination from handling.

If you want really super-thin "glaze" coats, thin with Tamiya lacquer thinner or Mr Color (lacquer) thinner, either of which will allow you to thin >75% thinner easily.

  • Member since
    July, 2013
Posted by modelmaker66 on Tuesday, January 31, 2017 6:38 PM

Phil h is absolutely right. Lacquer thinner will allow the fines spray possible allowing super slow and smooth buildup. Use low air pressure - psi.

  • Member since
    March, 2016
Posted by Haptesthai on Wednesday, February 01, 2017 1:03 PM

Hard to believe that my Fine tip was dead on arrival. I just replaced it with another 'new' one and it works like a charm now. I was very unsuspicious of it. Thank you very much everybody trying to help me here.

 

  • Member since
    March, 2010
  • From: MN
Posted by Nathan T on Wednesday, February 01, 2017 3:28 PM

Another helpful hint: You are using Gunze H series acrylic paint. They love 90% ISO, don't use water or any flow retarder. You can also use their MR. Hobby thinner with the blue label. It has a citris/alcohol smell to it, similar to Tamiya X-20A.

 

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