I was wondering if someone here could give me some pointers. I've got an Iwata HP-C airbrush. Its dual action. I haven't used it in awhile. Decided to do some work with it. Took it apart, and made sure everything was clean. So I poured the paint in, and when I try to spray it, the bubbles kept coming up into the cup. I also noticed, the spray flow, stutters. Like it won't be a continuous flow. It stops for a bit, depending on how much air is going through.

Any ideas what the problem might be?

Before I last used it, I had to put a new fluid nozzle in. And today, I replaced the needle with a new one I had kicking around.

 

splatters are usually cause the paint is not diluted enough
bubbles are the cause of an air leak, check that u have all the washers and all the seal tightened.
u can use teflon strips to seal the parts some more

 

This could be a really great thread for people.
I'm learning how to Airbrush, I got Badger 150 Dual Action.
Now here's a question for you.
Sometimes I get a "grainy/sandy" texture to my paint, once sprayed.
Not all the time, maybe 50% of the time.
Any advice?

 

again 2 possibilities
paint too thick or not enough air psi
when the paint is too thick the splatters are in big clumos when the paint thin its just wont keep the surface tension and leaks all over .

in low psi pressures there is enough force to force (lol) the paint out so it kinda stucks and the clumps of paint are thick and the texture is orange peel like

 

I've got the same air brush. it's great. sounds like your problem is one of the following...

(a) clog ; though you mention it was cleaned out, so unlikely
(b) needle bent ; even though it might look perfect a slight bend in the tip will block the paint & air from getting out
(c) paint is too thick ; dilute it

how is the climate where you are? sometimes, even if diluted properly, the humidity, hot temps or dry air might screw up the paint after a few seconds. Mix paint with hot air and it will instantly dry (problem I've been having lately with this ridiculous heat wave) I've adapted by thinning my paints way past an ideal thin to almost water thin, but by the time it goes through my air brush, it's thin like I need it.

 

Its not really a splatter. I've put water in the cup, and sprayed it. And while looking at the flow of the water, the flow itself stutters, instead of being even while being sprayed. I'll try the teflon tape tip out.

I had a new needle, that I never opened. Tried that one, and still got the problem. The issue happens with just plain water, as I sometimes do a check with water, to make sure the airbrush is work properly. It might be a clog though, somewhere inside where I can't reach. So I've given the airbrush a paint thinner bath over the day, to break up any paint that might still be inside. I made sure only metal parts were put in.

I'll let you guys know if it worked or not. Thanks for the tips.  

I have the same issue sometimes. Something I saw on a model kit forum. Try to strain the mixed paint through a cheese cloth, or nylon stocking. That intention is to remove any tiny lumps from the paint, before you pour it into the airbrush. I haven't tried this myself yet, as I haven't done much airbrushing in the last year.