I am having issues with airbrushing a primer coat. Sometimes the coat goes on smooth and others it is not and appears rough and bumpy. What is causing this? Is it air pressure? Do I need to thin it more? Any help is appreciated. Using Vallejo white primer.

Hi Scott, and welcome to Armorama! Vallejo primer is excellent stuff, so what is happening is called pebbling. It happens when you get a little too far away from the model and the paint partially dries on the way to the model. This causes the rough bumpy finish. Concentrate on staying closer and maintaining a wet edge.

Matthew thanks, that makes more sense. I was afraid at first if I got too close I would have had too much primer on the model and it would start dripping, etc.. Trying to touch up on my skills again and learn new ones. I will try this next time and see how it turns out. I really like the Vallejo line too, so it is obviously user error. Thanks for the advice

So what do you do to correct this? Sanding with something like 600 grit Sandpaper?

Hi! Yes, the distance of your subject to your airbrush can be one of the things that is giving you this "pebbling" and/or "orange-peeling" problem. Or, you may need to make some adjustments in your air/paint ratio. It's also possible that your primer may be a little bit too thick. You may also have water in your air lines. Even the weather may be affecting your spraying efforts. Humidity can have some really adverse effects on your painting sessions. Buying and installing a water-trap in your air-line is always a good investment in your spray-painting equipment.

Any paint or primer that you use in your airbrush should be thinned to the consistency of milk. You can compare the consistency of your milk vs your paint/primer mix by dipping the bare end of a small paint brush into the milk, and take note of how easily the milk drips from it. Add thinner in very small amounts to your paint/primer mix until it drips as freely as your milk.

What kind of airbrush are you using? You may have to alter your technique as well as your air/paint mixture.

Personally, I airbrush with 4 different airbrushes, all of which are "SINGLE-ACTION" types- I own 2 PAASCHE H-1 airbrushes with fine "needles", one of which I use strictly for "Metalizers". I also like my BADGER 200 with a "fine" needle, and my 200G "Gravity-feed" with "ultra-fine" needle for "touch-up" work. I LOVE my 200G especially when I spray those complicated "dappled" paint jobs on my 1/48 WWII German Fighter Aircraft. Many modellers like "Dual-Action" airbrushes- I've bought and tried a "Dual-Action; I found that I can achieve the same results with my "inferior" "Single-Action" equipment, so I sold my IWATA to a buddy of mine. He likes it, so good for him, and not much lost as far as I'm concerned...

You might also try straining your paints/primers into your paint cups before you start your airbrushing. There are numerous modelling books, magazines, articles, hobby-sites, ( Such as this one! ) and DVDs, etc out there that you can buy or simply download that you can put to good use. OSPREY's "Modelling Masterclass" books are especially helpful...

Sand with 1000 grit, or, preferably, strip it off with diluted ammonia.

Yep too far away bud. Matthew helped me out when I had that, it'll rub off very easily - it's not adhered properly

I can speak from experience, I use Vallejo primers and it is hard to get too much on a kit if you are just spraying it on. The stuff self levels and dries pretty well but wait a day or two to sand it. I learned that hard way when I first used it.