First things first, mine is the cheapest model (Neo for Iwata, sort of a legal knock-off really!) that can still be called a "proper" airbrush. That is with a double action trigger that controls both the flow of air and the flow of paint rather than a single action spraygun. A few immediate considerations:
Not cheap. My one with it's starter compressor (this deal) was £129. That is cheap for airbrushes. If you want a high end one? £300 or more just for the brush. Plus the compressor included is not good, you really want one with a tank as there is a slight pulse to the air flow without one. Expect to add about another ton to the cost to upgrade to a decent compressor. Then consider that it doesn't end there, you need thinners, isopropyl alcohol (isoprop) for cleaning... the list goes on.
Practice. Lots of the tutorials online make it seem like you can just pick the thing up and immediately get spectacular results. This is nonsense. You need to practice with one of these for a time equivalent to using a manual brush to get the same results if you are trying to paint a whole model with one. I just use it for what I call "airbrush specific" techniques. Mostly batch basecoating, weathering techniques and masked camouflage or vehicle heraldry. I wouldn't consider painting whole models with mine because...
Style. There is a particular style that the airbrush creates (if you use it to paint a whole model that is). It is a very smooth, cartoony look. Very popular, just not with me. If - like me - you appreciate the grimy, dark, realistic look (and as you read Pirate Viking Painting I kinda assume you do) then you'll only be using it for airbrush specific jobs only. Consider if you want to spend the money, especially as you can replicate most of the effects with a brush, it's just a little easier with the airbrush.
Cleaning. Urg, this is a real consideration. You have to be fastidious about cleaning these things. They suit a neat mindset, I don't have a naturally neat mind, its why I have a disciplined mind instead. It does mean that the airbrush can be a chore at times. Let me introduce you to post painting procedure:
|the back end has been unscrewed to expose the workings|
While you are working, paint goes in part 1, you use the trigger (2) to control the air by pressing down and the paint by pulling back the trigger. This pulls the long needle (3) back and opens the tip (4) - by the way, remove this protective cap before painting, all it does is fill with paint and drip. Just put it back on when finished to protect the needle. The air hose screws in at (5) and the whole thing is held together with a screwthreaded part containing a spring (6). Between colours you need to squirt some isoprop into the cup, rub around the innards with an old brush and empty into a spare container, do this twice and then run clean isoprop through the brush until the stream is clean. Seriously, this is what you do between every colour change. Then at the end of the session (and sometimes in the middle if you do a high volume or change to a light colour) you have to strip it down and clean thoroughly or the damn thing gums shut.
|note that the protective nozzle cap is gone now|
Clean out all the bits you can see with a few cotton buds (Q-tips if you are from over the pond) and more isoprop. Now we remove the nozzle, this is the part that I sheared off when retightening. That spanner is ONLY there to allow you to grip the thing, don't go any further than finger tight, it cannae take it Captain.
Now you can use a thin pipe cleaner (or in this case a rather overpriced set of "airbrush cleaning" bottle brushes of which only the thinnest of the set went through, hmm) to clean the tubes, run it a few times and rinse as it comes out of the nozzle.
Finally, reassemble the whole thing and give it a polish with a last bit of isoprop, after all that effort it is a shame if it doesn't look clean on the outside as well as the inside. This is a messy process, have copious kitchen towels and a beaker or something for excess alcohol. The whole process takes about a quarter hour. If this sounds like an unbearable drag then for the love of all that is holy do not buy an airbrush.
Mess & health: They are messy things, they create an aerosol of paint that falls as dust, also, you have to be intensely careful to mask everything as you won't believe how far this mist of paint can travel. If you don't have an extraction hood - and I don't - then you need to be masked too. A dust mask is a minimum but given some of the chemicals you will be spraying a filtering respirator is better. I forgot myself one time, used the thing for about an hour unmasked with liberal isoprop as thinner and cleaner and then got very lightheaded. I had been inhaling clouds of alcohol, see? Be ready for it and look after yourselves.
Paint: this is a choice thing. You can buy ready mixed paint perfectly suited to the airbrush but results are rather mixed.
The first pre-mixed I tried was Minitaire from Badger. Sadly, this has very, very mixed results, some are great, some - like the metallics - are bloody awful. Seriously, steer clear of anything shiny in this range. The other problem is the price, there is only one real retailer at the moment in the uk and they just convert the dollar price straight into pounds. Very overpriced. Vallejo Model Air is very good (the metallics are superb), cheaper too. But designed for military modellers, you won't easily find chapter colours for instance, that is more Minitaire's bag. You also tear through them. Airbrushes rip through paint and the thin, premixed stuff doesn't go far. My most recent attempt is using citadel acrylics thinned at a 4:5 ratio with Vallejo Airbrush thinner. The mixing bottle in the picture holds an entire thinned pot of citadel acrylics (in this case kantor blue) and thus guarantees a colour match when touching up. I think this will be my preferred method in future except metallics which Model Air will supply.
With all that I have said you might think that I don't think that you should own one. This isn't the case, for what it does well - those airbrush specific jobs - it is worth having. Not worth paying over the odds for (my cheapy one and teeny compressor is doing just fine) though. If you intend to get good with the thing and paint everything with one then shell out for the best you can afford at the very start. Seriously. Other people can recomend better than I if you want to become expert with this. I'll be sticking with the jobs I do with it. I've got 23:1 ratio of years experience with a manual brush vs airbrush. I'm too impatient to get the airbrush up to the same level! What I hope I have done is shown what is involved in owning and operating one of these tools. There are plenty of inspirational tutorials showing how cool they are. I just felt that you should be aware of the chores as well. Forewarned is forearmed as they say!