Airbrush spitting paint

[ScottsGT]

Iwata hp-cs

Lately when I start airbrushing, with the first push on the trigger to get the air flowing, I’m getting paint splatter coming out.  I’m having to point away from my work before pressing the trigger.   
I replaced the needle and brass insert/tip last year.  Seems this is a new issue that came up in the last few weeks. 
 

Anyone have any ideas? 
 

Edit: It’s not every time. 

[KevinM]

It happens to me at times seems to be the consistency of the paint with lacquers go thinner 15/17 psi.I Just did some acrylic Tamy white and went to thin with Mr.Level thinner and got a touch of spittle thinking acrylic is pretty thin out the bottle already?

 

I use a Badger Renegade fine tip.

[CANicoll]

Scott,

I also have the HP-CS and use it for most (80%) of my painting. You replaced the needle and nozzle last year which makes sense, but have you recently checked the tip to make sure there isn't a bend in it?

Does it happen with any paint, or just certain ones, like Vallejo Model Air which happens to me when I don't thin it properly?

The other thing to maybe look at is the needle fully seated in the nozzle?  I have done this, too.  I didn't fully seat the needle so some paint would seep in before even pulling the trigger.  UGH. Lastly, maybe repolish the needle so it is nice and smooth.

Good luck!

[DocRob]

Like others mentioned, check the needle and nozzle with a magnifier. I had slightly bent needles, which was barely visible with the bare eye and once I had a tiny split in the nozzle front. I hone my needles from time to time with a very fine Japanese sanding stone.
Another reason for spitting can be a change of temperature, humidity or air pressure changes of the compressor, which lead to pigments drying on the tip of the needle and cause spitting. Thinning or reducing the air pressure may help here.

Cheers Rob

[belugawhaleman]

I had the same problem recently....turned out to be moisture in the airbrush

hose. It was a humid day. The water trap had just a bit but the hose

had more. This was also causing paint to build up around the nozzle.

I knew the needle and nozzle were fine. I disconnected the airbrush

and quick connect from the hose and let the compressor run freely

for a while....problem solved. It's probably not a bad idea to do this after

each session. Later I turned the AC on to drop the humidity and continued

painting. The splurting was very frustrating but the model turned out fine.

 

[Peterpools]

Scott

The guys have pretty much covered almost all the reasons why your AB is 'spitting' at times. I've had the issue at times and for the most part, the paint seemed to be accumulating on the tip when the working air pressure was too low to how much the paint was thinned out. I paint at very low working PSI - around 12-15 psi's and at those low pressures, sometimes there isn't enough working pressure to keep all the paint from starting to build up on the tip.

I usually paint with either MRP lacquers or Tamiya acrylics and my AB of choice is the H&S Infinity Plus. Just a measure of good technique, I'll test the AB on a small piece of paper numerous times though out a painting session before moving onto the model surface.  At times, I'll clean/dab the AB tip with a Q tip with Mr Color Self Leveling Thinner to remove the visible drop of paint. The lower the working air pressure, the more frequent the tip paint build up will be. 

[ScottsGT]

Low pressure might be my issue.  I’ll experiment with it.  

[CANicoll]

I spray MRP at about 8-10 psi, and Vallejo Model Air at about 15-16 psi after thinning at least 30%.  I've not had spitting problems with the MRP, so I'm sure my issues are related to thinning and pressures with the acrylics.

[belugawhaleman]

Well, I've picked up some good tips from ths thread. In my case it was

moisture, but I learned about over thinning and low pressure causes.

I normally thin 50/50 Tamiya acrylic and levelling thinner and spray at

about 15 psi. This , I find works well with Tamiya x-22. I sometimes go

up a little pressure with the clear when I add a touch more thinner.

Chris, thanks for the info on MRP. I'm thinking of using MRP for a figure

build simply because of the color ranges offered. Also I like the airbrush

ready thing and that the paints are semi-gloss. 

Thanks all

Paul