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So, let me preface by saying that I haven't painted anything in about 3 years. I just got back into building models and WH40k, I've spent a lot of time assembling kits and minis, and now I'm ready to start painting. For models, I use my airbrush to paint a coat of primer and a basecoat, and for minis I usually use it just to prime and then hand-paint everything else.

I haven't used my airbrush in about 3 years. Busted it out, seemed to work fine, and so did the compressor. But when I tried to prime a model, all I got was this:





Sorry for the cruddy quality, but I think you can see that the paint just sort of speckled and splattered. I was using Vallejo gray primer, which is supposed to be airbrush-ready right out of the bottle? I tried thinning it and got the same result.

As for my rig, I have a Paasche H single-action siphon-fed airbrush. I have a compressor without a tank, but have it hooked up to a PSI regulator and two moisture traps, one on the compressor and another in the air hose. I've noticed that even with the regulator my air flow seems to pulse when I'm spraying.

I'm intensely frustrated because I want to get back into painting and can't seem to get past this hurdle. Spray primer is out of the question; I live in an apartment so there's no room for it, and at this time of year it's too cold outside to spray anyway. I've tried to hand-paint primer on some minis and it's really time consuming. On top of that, I'm painting Bad Moon Orks and the yellow looks like garbage because I can't get a consistent coat of primer when I hand paint it.

So... does anyone have some suggestions? Is it my airbrush? My compressor? Some combination of everything? Any advice would be appreciated. Airbrushing just gets so frustrating for me because there are so many different variables that can make things go wrong...

Looks like you've got a clog or corrosion in the airbrush itself. Disassemble to check the nozzle/needle/etc for corrosion or clogs. If you have airbrush cleaning fluid, give the parts a soak, and if you have one, a run through an ultrasonic cleaner.

Also, check your moisture traps and hoses for blockages.

Clean the airbrush check the tip. Usually gunk causes the specklig.

Use Vallajo flow improver afew drops, i just started using it and after painting without it for a year i can say it definitely helps.

Check out this video. Start at 2:45. This has helped me tremendously.

https://www.youtube.com/watch?v=rLeWGzJbHzI

Jey, check the nozzle! several times!
I had to check mine 5 or so times, before I started to understand where exactly the glob may be ... so: clean, clean, clean!

And test the flow of your airbrush on a spare piese of plastic. so you can check if it speckles before using your model!

Never had a problem with speckles, though. They looked fine as a base or pre-shade.

Test more, clean more.

Could be an airflow or paint flow problem around the nozzle area as people have mentioned.

Could also be the primer itself has gone bad if you haven't used it in a while. I stopped using Vallejo primer because I couldn't get it to stop spraying poorly and blowing little chunks, I realise now it was probably just my bottle had gone bad.

So try spraying something else and see if it works better.

Also post some pics of the StuG when you finish it, I love stugs

Like others have said - clean it.

Mine was pretty crudded up and I soaked it in Simple Green for a few hours then took a pipe-cleaner to its innards. Big globs of paint came out the first run through. It took several scrubs to get all of the paint out.

AllSeeingSkink wrote:
Could be an airflow or paint flow problem around the nozzle area as people have mentioned.

Could also be the primer itself has gone bad if you haven't used it in a while. I stopped using Vallejo primer because I couldn't get it to stop spraying poorly and blowing little chunks, I realise now it was probably just my bottle had gone bad.

I also found that Vallejo's primer need to be airbrushed at quite a high pressure, because of how thick it is. If the pressure is too low, I get speckles like that.
Although as mentioned above, a dirty nozzle also produces that.

Have found warming the primer slightly helps as well

fresus wrote:

AllSeeingSkink wrote:
Could be an airflow or paint flow problem around the nozzle area as people have mentioned.

Could also be the primer itself has gone bad if you haven't used it in a while. I stopped using Vallejo primer because I couldn't get it to stop spraying poorly and blowing little chunks, I realise now it was probably just my bottle had gone bad.

I also found that Vallejo's primer need to be airbrushed at quite a high pressure, because of how thick it is. If the pressure is too low, I get speckles like that.
Although as mentioned above, a dirty nozzle also produces that.

What I'm talking about is the paint actually going bad. I think it's whatever rubberiser they have in it going off, like, starting to react in the bottle even before it hits the model.

I tried lots of different pressures, I tried running more and less thinner in the primer, I even tried nozzles from 0.3mm all the way up to 0.7mm and it would improve but still give a splattery finish compared to other paints and primers.

If I recall correctly Vallejo actually recommends that you use a lower pressure for their primers, but the bottle was terrible at all pressures and even worse at low pressures.

Regular paints wouldn't do the same thing and I eventually just swapped to Gunze Mr Surfacer for my priming needs.

Throwing the Vallejo primer in the bin was the only solution that worked

Not saying that definitely is the problem, it's just a possibility if coming back to painting after 3 years that there's a good chance some of your paints (particularly Vallejo Airs and primers) might have gone bad.

Vallejo primer is extra gunky cloggy. Add flow improver and water. so like 25/25/50 water/flow improver/pimer.

Ok, so general consensus is try to clean it some more! I have some Iwata airbrush cleaner, but that stuff's pricey so I think I might pick up some Simple Green if I want to soak stuff. I might pick up an ultrasonic cleaner too, depending on how many Amazon gift cards I get from Santa

Another question that I have: how exactly do you properly read a PSI regulator? For example, before I start spraying it might read 20 PSI, but as soon as I get air going through the brush it will read 10 PSI. Which one is the actual PSI the brush is spraying at?

For reference, this is the regulator/moisture trap I have. It's tacked right onto the compressor.

AllSeeingSkink wrote:

Also post some pics of the StuG when you finish it, I love stugs

I didn't choose the StuG life, the StuG life chose me.

Soak your brush in Simple Green (not the whole thing, just from like the pain cup to the nozzle), take it apart, clean it all out with pipe cleaners/toothbrush.

I add a couple drops of water and Flow Improver to Vallejo Primer, and then spray it around 18 PSI.

Reading your pressure: With no airflow in the airbrush, you are reading the tank pressure. When you squeeze back the airflow switch on your gun and the air pressure goes down- that's the pressure you are spraying at. It will always be lower than your tank/compressor is because it has to fill the airline from the tank/compressor to the airbrush. With no paint in the airbrush, pull back on the switch until it stops. Then adjust your air to whatever PSI you want (try around 20-22 PSI; I lose about 3-4 PSI through my airbrush, and I never spray above 20 PSI unless I have a clog).

I tend to shoot everything around 15-18 PSI; A lot depends on the paint. Always have a note card or something nearby to test your spray pattern and PSI on before you start shooting paint on a model. It will save you a ton of headaches later.

Good luck!

Simple green is good. Just put it upto the cup. Be careful with the sonic cleaner, only use water, i hear the sonic cleaner + cleaners as they can actually stripe away the metal on the brush, not sure if it true, just what i have read.

For pressure, when you pull the trigger it drops, thats what you are spraying at. I generally shoot at 15 for delicate stuff, base coating and primer I go about 25. (this is after you pull the trigger)