Correct pressure for airbrush?

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SLSF1

New Member
I've been inactive for several years, but am getting back in the game. I want to weather some of my model rail cars with my airbrush and need a refresher on what air pressure to use. I have a Paasche VL airbrush. I have some Floquil paints I'd like to use, and when my supply runs out was planning on switching to Modelflex acrylics.

What pressure range should I use for Floquil? Memory seems to tell me 20 to 25 psi. What pressure should I use with Badger Modelflex? I saw one recommendation of 25 to 30 psi.

All advice will be appreciated. Thank you!
 

wvg_ca

Well-Known Member
i use 15 psi or close to that ... but my paints [mostly krylon] are thinned and kinda runny .... less pressure and thicker paint for weathering, i like that it goes on a bit unevenly ..
 

jpolacchi

New Member
As Alan said,depends on the paint and how much it was thinned(or how much you can thin it). I've seen urethane paints airbrushed at 7psi,but that's an entirely different animal. Acrylics,enamels and even lacquers have their maximum you can thin them before the paint lacks any adhesive or structural qualities after it dries and cures.Over thinned acrylics will crack...mixing an enamel or lacquer "too hot" has its own issues.Especially in "hobby use".The solvent will attack most plastics and the paint will most likely crack and flake off after it dries.I imagine also that over thinned solvent paints will have "drying" problems being that your surface may be pebbly as it dried prior to being applied to its surfaces. There are some instances where you might get away with mixing a paint a little on the *hot* side(maybe if its cold?),but its a tricky tight rope to balance on.You are more or less "married" to the limitations of how much an acrylic can be thinned. I think "standardly speaking" most paints can be thinned 20-25% and sprayed around 15 psi. although sometimes at a higher psi. I've seen youtube videos of others thinning down Flowquil or Model Master enamles with cheap lacquer thinner by 50% and that's a fairly hot mix I think?Could possibly run it below 15psi,but depends how it looks when you spray it out.
 

jpolacchi

New Member
Also, when you go to acrylics, because they dry faster, you must clean your airbrush right after use.
Absolutely(unless you added a retarded to it) you have a little more time,but you should fully break down and clean your airbrush every time you are done using it because if you don't(as you said) the paint dries and it is harder to clean.
 

AirbrushNo5

New Member
It varies with how much the paint is thinned…
I am using Tamiya… I like it thinned a lot… so I can build up light coats of fade or grime that look natural to my eye
15 psi…sometimes less as the regulator pressure drops…
 

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jpolacchi

New Member
It varies with how much the paint is thinned…
I am using Tamiya… I like it thinned a lot… so I can build up light coats of fade or grime that look natural to my eye
15 psi…sometimes less as the regulator pressure drops…
Well "technically" the more you thin the paint and lower its viscosity,the lower you can run the psi on your airbrush. Most paints have limits to how much you can think them (excluding maybe water colors or maybe super thinned oil paints?).Not sure I'd airbrush artist oils although I had tinkered with the idea.Many of the colors have toxic elements in them that make up the pigments. I think they used to have lead in some of them,not sure about that any more?They may have ceased using lead,but cadinum and iridium I don't think are good for you?I think Urethnanes are an exception to the rule because they are so different from most of the rest of the paints.Then again, most all folks don't use urethanes in the "hobby field".They tend to be far more expensive(some colors are hundreds of dollars per quart) and are a bit tricky to use.So not for a novice and I wouldn't mess with them myself.There's two types. Stage 1 and stage 2 urethanes. I forget which,but one requires a catalyst to be added.However,they are pretty incredible.I watched someone at a car show (during a demo) airbrushing some pretty intricate work at 7psi. He literally was holding the airbrush 1/4 inch from the work surface with "no over spray". You can thin those down to water consistency practically and the paint doesn't have any real issues like say,an over thinned enamel, lacquer or acrylic would. Its sort of like airbrushing superglue and it really bites into metal and most plastics and dry as fast as lacquers do.
 

AirbrushNo5

New Member
I think when the paint comes out “right” I am at the right pressure for airbrushing…
I always blow some paint out on scrap before I start on the model..
Low pressure I can get closer to the subject..
I just started weathering cars last spring and it’s a matter of trial and error, figuring out what works and what doesn’t, what you can do and what you need practice at…
I’m still working at it
 

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