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Vallejo model air - what PSI for thin lines?

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  • Member since
    October, 2013
Vallejo model air - what PSI for thin lines?
Posted by redryder on Wednesday, July 22, 2015 9:55 PM

Hi, I tried using Model Air for preshading panel lines. I thinned it with vallejo thinner, and set the PSI to 10. Vallejo's FAQ specified 10-15 bar for model air. 

However, instead of a nice thin line I got dots like the picture above. When I tried airbrushing larger surfaces at 20 PSI I would still get dots. I had to crank up the PSI to 30 before getting a smooth spray. But at that PSI the paint would spray out so much that it looked glossy and wet on the piece and threatened to pool. 

Any guidance on what PSI to use for model air? 

  • Member since
    October, 2007
  • From: Scotland
Posted by Milairjunkie on Thursday, July 23, 2015 4:41 AM

It looks very much like the paint isn't being atomized properly & is just spitting out of the airbrush - droplet size reduces with pressure, but you shouldn't have to go up to 30psi to get decent results. The following may help;

Check your airbrush - have a good look at the needle tip & nozzle for condition & make sure that there isn't any blockage in the air path (gummed up air valve, air channel or nozzle cap/air cap).

Try adding more thinner.

Considering adding a airbrushing flow aid (which will reduce surface tension). 

 

What sort of airbrush are you using?

  • Member since
    October, 2008
  • From: England
Posted by P mitch on Thursday, July 23, 2015 5:45 AM

I agree with Milairjunkie it looks your brush has a problem. You can also add some retarder which will slow the drying time but not effect the spray pattern your getting it will just dry a bit smoother.

Phil

"If anybody ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me: it's all balls." R J Mitchell


  • Member since
    October, 2013
Posted by redryder on Thursday, July 23, 2015 7:12 AM

Thanks guys. I'm using an Iwata Eclipse CS. I've soaked my nozzle in airbrush cleaner, and cleaned it out with a small brush.

I'll try it again tonight with more thinner and retarder and see how it goes.

  • Member since
    October, 2013
Posted by redryder on Thursday, July 23, 2015 8:15 AM

I've taken more photos, with how the paint looks at different PSIs and different distance to the paper. Does this look normal to you?

Same paint was used for all photos - Vallejo model air thinned 1:1 with Vallejo airbrush cleaner

  • Member since
    October, 2008
  • From: England
Posted by P mitch on Thursday, July 23, 2015 10:07 AM

There is something wrong there all right. I've never used a thinner with Model Air just straight from the bottle. As your using a gravity feed brush getting a think line should be fairly easy and at about 1cm thats the distance I would use.

Take the airbrush completely apart and check the needle for problems and check the fluid nozzle for splits, I've had one on my Airbrush and it caused some issues. Get the needle on the tip of your finger and just roll it across to see it there is any bend. Use a maginifying glass to check the needle and the fluid nozzle as well, any split or burr with cause problems. After that you'd need to look at the air passages but my guess at the moment would be that the fluid nozzle has a split.

Is there a small plastic washer in the head? Did you soak it in cleaner when you soaked the head? If you did the washer could have split as well causing air to get in that way. Never soak washers they will perish

Phil

"If anybody ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me: it's all balls." R J Mitchell


  • Member since
    May, 2013
  • From: Indiana, USA
Posted by Greg on Thursday, July 23, 2015 10:21 AM

Oh, that pattern is not right for Vallejo model air thru an Eclipse, any needle/nozzle combo (I use both), or any of the pressures you tried.

1:1 is way too thin for model air, and I'm concerned that you stated you are thinning with Vallejo airbrush cleaner. Vallejo airbrush cleaner is not the same animal as their airbrush thinner, and could possible be a big part of the problem.

(this is just my 2 cents in addition to the good advice you've already gotten from MJ and Phil.)

-Greg

  • Member since
    June, 2015
Posted by Samurai on Thursday, July 23, 2015 11:22 AM

Vallejo seems to work better with either their thinner or a few drops of water. I tried mixing it with Tamiya and it started to spatter like that and got chunky. The Tamiya paint was already thinned with an alcohol/ water mixture.

  • Member since
    January, 2013
Posted by BlackSheepTwoOneFour on Thursday, July 23, 2015 12:18 PM

Damaged tip perhaps?

  • Member since
    December, 2011
Posted by Chrisk-k on Thursday, July 23, 2015 1:02 PM

IME, Vallejo Model Air sprays more poorly than Tamiya and Testors acrylics.  

When I use Model Air, I have to crank up psi to 30 to get smooth results.  This is a reason why I hardly use MA although I have 15 bottles of MA.

Iwata HP-CS | Iwata HP-CR | Iwata HP-M2 | H&S Evolution | Iwata Smart Jet + Sparmax Tank

  • Member since
    May, 2013
  • From: Indiana, USA
Posted by Greg on Thursday, July 23, 2015 5:12 PM

In defense of Chris' position, I've not a whole lot of luck with fine lines and VMA.

I wonder, Red, do you realise how quickly VMA will go dry tip on you? For example, if you're not cleaning your tip between your little sample lines, your tip is probably dry already.

-Greg

  • Member since
    April, 2018
Posted by Panzer Joe on Monday, April 16, 2018 6:54 PM

Can you thin normal Vallejo paint and spray paint with it?

  • Member since
    May, 2013
  • From: Indiana, USA
Posted by Greg on Monday, April 16, 2018 8:06 PM

Panzer Joe

Can you thin normal Vallejo paint and spray paint with it?

 

If by 'normal' you mean Vallejo Model Color or Panzer Aces, etc, the answer is yes......

But I'd follow with I wouldn't recommend it. It is unreliable at best and I'm biting my tongue. I had a bad experience doing just that the other day, and I darned near threw three plastic cases of Vallejo out.

Vallejo is my primary paint, fwiw. And this is just my experience. Other Vallejo users milage may vary.

And yes, I know this is an old thread.

-Greg

  • Member since
    April, 2018
Posted by Panzer Joe on Tuesday, April 17, 2018 4:12 AM

Ok thanks for the advice might get Vallejo air instead 

  • Member since
    May, 2013
  • From: Indiana, USA
Posted by Greg on Tuesday, April 17, 2018 9:50 AM

Panzer Joe

Ok thanks for the advice might get Vallejo air instead 

 

You're welcome, and I think that's a good idea.

Once you have some experience with Model Air, it might then be less frustrating to try spraying with Model Color.

Good luck.

-Greg

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