Hi folks! I've noticed that depending on PSI - there is a small time gap between finger-trigger movement and the actual starting of the paint flow from the nozzle. I'm using GSI PS270 and Createx Illustration paints. Even heavily reduced paint (1 paint : 19 reducer) is not starting to flow immediately after I pull the trigger slightly on ~15 PSI, but if I raise the pressure to say 25 - I start to flow almost instantly. Is this behaviour airbrush dependent? Tested on the clean airbrush.
Paint flow
- Thread starter Alex
- Start date
DaveG
Airbush Analyst
paint is drawn from the nozzle by a change in air pressure over it's tip. The higher the air pressure, the higher the change in pressure, and thus the faster the paint flow... You also have to overcome surface tension in the paint, which keeps it stuck to the needle, the paint channel through the brush, and everything else it comes into contact with, prior to being stripped from the needle tip by the air flow over it.
Kim McCann
Mac-Valve Maestro!
To add a bit to Dave's answer...
There are also another couple of factors that are airbrush dependent. The length of the paint channel between the color cup and the nozzle can also play a factor when spraying, depending on the consistency of the paint, and whether or not there is already enough paint in the channel to send out. For example, gravity feed cups usually have a slightly faster paint flow response than side feed, or siphon feed airbrushes, as thanks to our friend gravity, there will almost certainly always be paint already in the paint channel around the needle. If there is enough time between strokes in a siphon feed, gravity will tend to pull the paint back down into your bottle, and you might need just a fraction of a second more to get paint flowing.
So along with air velocity coming out the front, the length of the paint channel and the type of airbrush can also play a role. In regular use however this is usually just a tiny fraction of a second, and often something you might not notice. If you switch back and forth between brushes in the same session, or are experience, especially in detail work, you may notice the difference and come to adjust your pressure, or style to compensate when starting or stopping lines.
With siphon or side feed, as long as you keep paint in the channel all the way to the tip (don't wait a long time between lines), well... the start time should be as fast as any gravity feed.
Almost all that a regular user will notice tho, is the the amount of air pressure will definitely effect paint flow speed, due to the reasons in Dave's excellent explanation.
There are also another couple of factors that are airbrush dependent. The length of the paint channel between the color cup and the nozzle can also play a factor when spraying, depending on the consistency of the paint, and whether or not there is already enough paint in the channel to send out. For example, gravity feed cups usually have a slightly faster paint flow response than side feed, or siphon feed airbrushes, as thanks to our friend gravity, there will almost certainly always be paint already in the paint channel around the needle. If there is enough time between strokes in a siphon feed, gravity will tend to pull the paint back down into your bottle, and you might need just a fraction of a second more to get paint flowing.
So along with air velocity coming out the front, the length of the paint channel and the type of airbrush can also play a role. In regular use however this is usually just a tiny fraction of a second, and often something you might not notice. If you switch back and forth between brushes in the same session, or are experience, especially in detail work, you may notice the difference and come to adjust your pressure, or style to compensate when starting or stopping lines.
With siphon or side feed, as long as you keep paint in the channel all the way to the tip (don't wait a long time between lines), well... the start time should be as fast as any gravity feed.
Almost all that a regular user will notice tho, is the the amount of air pressure will definitely effect paint flow speed, due to the reasons in Dave's excellent explanation.
