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Airbrush mottling, or "reverse clumping"

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  • Member since
    September, 2018
Airbrush mottling, or "reverse clumping"
Posted by msaspence on Wednesday, September 05, 2018 1:52 AM

I've just started airbrushing and after a successful practice on a paper pad I got cracking on my Trumpeter Type 23 Frigate. The paint seems to go on great (not spattering on clumping in the air) and then almost instantly a mottled affected is revealed, almost like the paint is doing the oposite to pooling or clumping together. 

I've tried a few different pressures and consistencies of paint, I'm on my third coat and the pattern still emmerges. 

I'm using a dual action side fed airbrush and Vallejo game color paint with Vallejo airbrush thinner.

I've just realise I didn't clean the part, could it be cause by release agent still on the plastic?

 

  • Member since
    August, 2017
Posted by laskdjn on Wednesday, September 05, 2018 9:34 AM

msaspence

I've just started airbrushing and after a successful practice on a paper pad I got cracking on my Trumpeter Type 23 Frigate. The paint seems to go on great (not spattering on clumping in the air) and then almost instantly a mottled affected is revealed, almost like the paint is doing the oposite to pooling or clumping together. 

I've tried a few different pressures and consistencies of paint, I'm on my third coat and the pattern still emmerges. 

I'm using a dual action side fed airbrush and Vallejo game color paint with Vallejo airbrush thinner.

I've just realise I didn't clean the part, could it be cause by release agent still on the plastic?

 

 

 

That could be part of it, also how thin did you make your paint?  The reason I ask is because Game Color is intended for brush painting, while their Game Air line is meant for Airbrushing.  Now Game Color can be used for airbrushing, but you have to thin it way down.

  • Member since
    December, 2002
  • From: NYC, USA
Posted by waikong on Wednesday, September 05, 2018 9:44 AM
that sounds like the problem, there's some chemical on the plastic preventing the paint from adhering properly. Sometimes is the release agent, sometimes it could be as simple as oil from your hands.
  • Member since
    September, 2012
Posted by GMorrison on Wednesday, September 05, 2018 9:53 AM

Problems with release agents is not present in modern kits. I think your issue, which I had recently with Tamiya acrylic and thinner, is a thinner/ paint ratio or compatibilty thing.

Paper and plastic of course have completely different absorbsion and drying characteristics.

Try practice on a trash kit.

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Wednesday, September 05, 2018 10:58 AM

I agree with the last two posts.  Any time I have had mottling, it has been due to contamination of the surface from something that does not allow the paint to wet the surface.

 

Don Stauffer in Minnesota

  • Member since
    May, 2013
  • From: Indiana, USA
Posted by Greg on Wednesday, September 05, 2018 11:34 AM

Learning to airbrush can be frustrating.

Learning to airbrush using 'acrylic' paints not designed to be airbrushed can be really frustrating. Indifferent

I'd suggest trying some Vallejo Model Air, Tamiya, or the new Mission Models folks are raving about first, then figure out how to spray the thicker Vallejo 'meant-to-be-brush-painted' stuff later.

I'm in my 5th year of working with Vallejo, and I spray Model Color or Game Color as an absolute last resort, and curse myself for ever stopping drinking beforehand. Toast

2 cents

-Greg

  • Member since
    January, 2013
Posted by BlackSheepTwoOneFour on Wednesday, September 05, 2018 4:51 PM

Vallejo Game Color is the culprit because it’s not made for airbrushing. Although you can but they’re not the greatest acrylics around. I second Mission Model paints. 

Vallejo tends to be more like vinyl-y based (at least to me).

  • Member since
    May, 2013
  • From: Indiana, USA
Posted by Greg on Wednesday, September 05, 2018 6:36 PM

Hey Sheep,

I know you've told me before, but can you say again where you buy your Mission Models paints please? I feel about to break down this time.....

TIA

-Greg

  • Member since
    January, 2013
Posted by BlackSheepTwoOneFour on Wednesday, September 05, 2018 10:05 PM

www.scalehobbyist.com

Mission Models have added more new colors to their line too.

  • Member since
    September, 2018
Posted by msaspence on Thursday, September 06, 2018 6:50 AM

Thank you everyone for your tips.

Dispite there being some disagreement around whether modern kits suffer from release agent, I'm fairly sure that was to blame at least in part. Of course it could have been some other chemical or oil, but the paint I had put on had not adhered at all really, dispite being on there about a day. It washed off easily just by running water over it. Once I'd striped it back I gave it a good clean with an electric tooth brush and soapy water. 

I gave it another shot with the Game Color, but thicker and with a higher pressure and had much better results. It mottled a bit, but just a couple of small barely noticable spots. 

I ordered the colors I need in Game Air for the rest (just done a first layer on the hull so far). It made sense to stick with Vallejo so I have the same colors to brush if, nay when, I need to touch up. I will give Mission Models a try some time soon though.

 

  • Member since
    May, 2013
  • From: Indiana, USA
Posted by Greg on Thursday, September 06, 2018 12:33 PM

BlackSheepTwoOneFour

www.scalehobbyist.com

Mission Models have added more new colors to their line too.

 

Thank you, Sheep.

OP, sounds like you are making some progress. Progress is good.

-Greg

  • Member since
    January, 2013
Posted by BlackSheepTwoOneFour on Thursday, September 06, 2018 3:19 PM

msaspence

Thank you everyone for your tips.

Dispite there being some disagreement around whether modern kits suffer from release agent, I'm fairly sure that was to blame at least in part. Of course it could have been some other chemical or oil, but the paint I had put on had not adhered at all really, dispite being on there about a day. It washed off easily just by running water over it. Once I'd striped it back I gave it a good clean with an electric tooth brush and soapy water. 

I gave it another shot with the Game Color, but thicker and with a higher pressure and had much better results. It mottled a bit, but just a couple of small barely noticable spots. 

I ordered the colors I need in Game Air for the rest (just done a first layer on the hull so far). It made sense to stick with Vallejo so I have the same colors to brush if, nay when, I need to touch up. I will give Mission Models a try some time soon though.

 

 

 

Soon, you will come to a point that Vallejo isn’t worth buying or airbrushing any more. That’s why I stopped buying their colors. Thank god I only bought  like 4 or 5 colors. I use their Off White exclusively for all my D-Day subjects by handbrushing them instead. The D-Day stripes were never sprayed on but brushed on aircrafts during WWII.

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