Hi, When people talk about airbrushing at a certain psi (e.g. 12,15,20 etc..). Are they referring to the reading on the gauge when the airbrush trigger is depress? I noticed that the pressure drops by about 7-10 psi when the trigger is depressed. If anyone would clear that up for me that will be great. Thanks.
Pressure shoudln't drop that much! Sounds like you have a bad regulator. I would say it was reasonable for the pressure to drop by
2-3 psi.This is not an exact science anyway. Pressure depends on personal airbrushing style, paint thickness, nozzle size, distance to the painted surface, etc.
Most people mention the pressure when the air is flowing through the brush. It would be illogical to mention pressure when the airbrush isn't being used....
:-) Peteski
That 7-10 is a normal pressure drop with a Paasche H, the pressure drop with an Iwata HP-B is about 2-3 pounds.
Actually I set my regulator with no air flowing because it's easier to do where my regulator is located (compressor under the bench).
I agree. My pressure drops 2 psi when trigger is depressed. However, when I recommend the 15 psi, that is with no flow. It is about 13 psi with flow. For flats, if I want a really flat coat, I go up to 20 psi no-flow, which is about 18 psi with flow. It isn't critical, however. I can get a reasonable gloss even with 20 psi (though 15 is easier), and a reasonable flat at 15, though 20 is easier.
In addition to regulator, it could be the compressor. I use a big honking Craftsman with a big tank. A very small compressor will drop much more under load. I would crank up the pressure so the pressure under flow is in the 13-20 range.
Just hold down the plunger then adjust your pressure!
I agree. I've seen (and bought!) some cheesy "pressure regulators" that really aren't much more than a needle valve. A proper regulator has a rubber diaphram and an adjustable spring. You should expect to pay $20 to $50 for a good one. Having the kind of pressure drop you describe will make it very hard to do delicate work.
Greg Reynolds, IPMS
I stand (well, sit) corrected. I didn't realize that people were giving the pressure spec when the airflow was off. Especially since there is usually a bit if a differential.
So I should say that I woudl specify the pressure I use while the air is flowing through my airbrush. That's what's logical to me.
Peteski
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