Air Pressure

There is no "correct" pressure, as it depends on the type of airbrush and how thick/thin the paint is. I know a guy who thins his paint to 30% paint & 70% thinner (or even thinner) and sprays between 40-50 psi, and his work is incredible.

I use 17-20 psi when I use my internal mix siphon fed 200 and 150, but external mix airbrushes requires a bit more oomph and 20-30 psi is a good target range.

Your graininess is caused by the paint drying before getting on the surface, and orange peel happens when paint dries before leveling out. Both are caused from spraying too far away, 6" or less is the distance to work at. Most of the time I'm between 2-4".

Do yourself a favor, turn down the pressure to between 15-18 psi. You don't have to hear the airbrush screaming as it sprays. You'll find your paint flows and covers with better appearance...advice given from someone who used to use 40-50psi all the time!!!

I used to spray at 20 PSI and higher no matter what type of paint or airbrush I was using.  Then I started experimenting with lower air pressure and  immediately  got better results.  Now I start at 15 PSI and go up or down from there.  I seldom us anything above 20 PSI these days.

Ditto on 15-20 PSI. Works good for me anyway.

Mike,

 On my Paasche H, I also noticed better results by lowering the tip/needle no more than 1/8". By this (my theory) the tip is more into the airflow, gets atomized better, I can use lower pressures, and get closer to the work. Still experimenting, but it seems to work. Should state that I was using the H-3 nozzle, Testor's enamels  thinned 3 to 1.

All,

Thanks for the information.  Come to think of it, I believe I am holding my airbrush 6" or further away from my models.  That and for general WWII A/C paint schemes (OD  upper - sky or grey lower) I set my needle about half travel.  So, I guess I'm throwing too much paint at too great a distance(?). 

Bushman32,

When you say "lowering the tip/needle" you're saying from the fully closed position, right?  When I thin my Model Master enamels to what I "think" is the right consistancy usually ends up around 2 parts thinner to 1 part paint, but that varies naturally.  Hmmm, maybe I'm looking at cream instead of 2% milk and should try thinning a little more 

Thanks again,

Michael B.

Personally I use 15 for glossy finishes, 20 for flats.

I have been setting the assembly with the tip about half way open, then loosening the set screw, I slide it down just a little. Paasche told me not to go farther than 1/8". On thinning the paint, I have just been going by Testor's recommendations for flat enamels- 3 parts paint to 1 part thinner. I was originally have problems with a couple of small paint drops coming out, along with the normal spray, when I first hit the trigger. This was using the H-5 set up. So, taking what I have been told on this forum, by Paasche, and my club members, I have been experimenting and still am. Lowering the assembly appears to give better atomization, at least it appeard to clear up those few little drops. But, this can all change tomorrow.

Bgrigg

There is no "correct" pressure, as it depends on the type of airbrush and how thick/thin the paint is.

Bgrigg, this is the "right" answer. But many new airbrush users are afraid to experiment and want a black and white answer. Many who gave "a single pressure range" answer without asking what type of airbrush was used and how he thinned the paint are actually very countproductive.

I use 17-20 psi when I use my internal mix siphon fed 200 and 150, but external mix airbrushes requires a bit more oomph and 20-30 psi is a good target range.

The "20-30 psi" range is what I used with my Paasche H, an external mix and siphon feed airbrush. It does not atomize well using lower pressures.

Your graininess is caused by the paint drying before getting on the surface, and orange peel happens when paint dries before leveling out. Both are caused from spraying too far away, 6" or less is the distance to work at. Most of the time I'm between 2-4".

You hit the problem on the head. If Michael tries lower pressure, it may make his problem worse.

It may not be practical to paint at 2-4" all the time. The paint needs to be thinner and with retarder if painting at a larger distance.

Practice, practice, practice is the rule when learning to airbrush. Many people will do a bit of practice using paper, or cardboard, and then wonder why they don't get good results with plastic.

Sacrificing a cheap kit for practicing on is well worth the money. It's doesn't have to be a good kit, the cheapest one in the store will do. I use a 1:72 kit I bought for less then $10. I didn't bother with the cockpit (not that there was much of one!) or masking the canopy. Using Tamiya Acrylic paint allows me to wash off the paint for the next application. I use it every time I paint so I can be sure that the pressure or paint consistency is correct before applying paint to a "real" model.

2-4" is just my typical working distance, sometimes I have the needle almost touching the surface. The point I was trying to make was to get closer to the model so the paint can work properly. You are quite correct that with the proper thinning and addition of a retarder you can back away from the surface.

Bgrigg

Practice, practice, practice is the rule when learning to airbrush. Many people will do a bit of practice using paper, or cardboard, and then wonder why they don't get good results with plastic.

Sacrificing a cheap kit for practicing on is well worth the money. It's doesn't have to be a good kit, the cheapest one in the store will do. I use a 1:72 kit I bought for less then $10. I didn't bother with the cockpit (not that there was much of one!) or masking the canopy.

And there's lots of free plastic in your trash that works just as well.

Don

  I use whatever my compressor is putting out, I dont even know how much it is lol. i have no knobs on it to adjust?

I just adjust my pressure  by how much I push down the trigger on the AB seems to work out fine lol

Don Wheeler

And there's lots of free plastic in your trash that works just as well.

Don

This is true, and I started out using milk jugs and yogurt containers, but I found the surfaces weren't quite the same. They are certainly better than paper products!

My favorites are water and juice bottles.  And I still keep a couple handy.  I give them a couple of shots to warm up with and see how the paint is going down.  If the bottle looks OK, so will the model.  I also use them to test decal setting solutions.  I take something I don't need off the sheet and experiment on a bottle.  I do this with every kit.  It eliminates nasty surprises.

Don

JTRACING

  I use whatever my compressor is putting out, I dont even know how much it is lol. i have no knobs on it to adjust?

I just adjust my pressure  by how much I push down the trigger on the AB seems to work out fine lol

I envy your sensitive touch.   My trigger is pretty much on or off.  I've read so many varying opinions, that I've come to believe that pressure and thinning are two things that can vary over a pretty wide range and you can still get good results if you learn to compensate.  I suspect that you have learned to work with whatever your compressor is putting out and as long as it doesn't change it doesn't matter.

Don

JTRACING

  I use whatever my compressor is putting out, I dont even know how much it is lol. i have no knobs on it to adjust?

I just adjust my pressure  by how much I push down the trigger on the AB seems to work out fine lol

You'd need a regulator to adjust your PSI.

Don Wheeler

 

JTRACING:

  I use whatever my compressor is putting out, I dont even know how much it is lol. i have no knobs on it to adjust?

I just adjust my pressure  by how much I push down the trigger on the AB seems to work out fine lol

 

 

I envy your sensitive touch.   My trigger is pretty much on or off.  I've read so many varying opinions, that I've come to believe that pressure and thinning are two things that can vary over a pretty wide range and you can still get good results if you learn to compensate.  I suspect that you have learned to work with whatever your compressor is putting out and as long as it doesn't change it doesn't matter.

Don

Sorry but you can't control the air pressure with the trigger much at all and no airbrush expert will tell you to even try to.

If you can then you are more skilled than any airbrush artist I have ever talked to including Dru Blair.