I had to pause my return to modeling for a year or two as we moved, but now am back at it. Having started to paint the latest creation I have been getting very inconsistent results with my airbrush (Iwata HP-CS), which is starting to jog some memories of frustrations before I moved.
Basically, what I am finding is that the brush appears to behave inconsistently in the type of spray that its putting out. One very specific example is that with a fairly thin paint mix, when I start pulling back on the valve, paint will flow, for 2 - 3 seconds and then stop. This really seems to apply when trying to do detailed lines. So for instance, I get very close to the surface, pull back enough to start a fine line, move the brush 2 or 3 inches, and then it stops, all without changing needle position. Sometimes it will start again on its own, sometimes I have to move the needle a fraction of an inch for it to start again, which it will do without splatter or a mess.
The brush also seems to be really inconsistent with how it handles paint of any given thickness. Sometimes it will splatter with fairly thinned paints, sometimes it wont, etc.
With that said I have deep cleaned this thing very thoroughly. The paint cup is clean, the needle is perfectly clean, the nozzle is spotless, and so is the nozzle cap. To the naked eye the needle is quite straight and seats well in the nozzle. The nozzle itslef appears to be very well formed in that when assembled the nozzle is concentric to the opening in the nozzle cap.
One thing that I did notice, however, is that the needle does not retract in a concentric manner to the nozzle. When its being pulled back the needle always slides to one side and rides the edge of the nozzle back into the brush. Is this an issue? I know that ideally this would not be the case, but at a .35mm opening, I find it hard to believe that all of these brushes are machined with tolerances that are good enough to prevent that.
At this point I am thinking of just ordering a couple of new needles and nozzles for the brush because I can't come up with any other solution. I feel like I have tried every combination of pressure and viscosity that I can think of.
Id love to get any feedback or ideas that you have.