This is a post I’ve been meaning to write for a long time. After all, airbrushing is probably my favorite single aspect of modeling. And, with all the airbrushing talk that’s been swirling about the interwebs lately, it seems like the time is right.
So what is this? It’s a deep – I hesitate to say exhaustive – dive into many, many facets of airbrushing, from airbrush selection to paint selection to mixing paints to spray discipline.
Here are some in-post links if you want to skip ahead:
- I – Choose Your Weapon
- II – On Selecting Primers
- III – Paints
- IV – Thinner and Air Pressure
- V – How to Airbrush
Part I: Choose Your Weapon
A – Do I even need an airbrush?
In my opinion, yes. It’s possible to limp along in this hobby with paintbrushes and rattlecans, and even thrive in certain genres like figures, but the atomization, precision, and layering capabilities of an airbrush simply cannot be matched by other means.
B – I’m just going to buy a cheap knockoff. High-end airbrushes aren’t worth the money.
Uh, hold on there, chief.
Think of airbrushing like driving, and airbrushes like cars.
If all you’re doing is driving to and from work each day in traffic, you’re not pushing the performance envelope of any car at all. You can get by just fine in any random shitbox. The same goes for airbrushing. If you’re going to setup at standoff distance and just hit a model with a single color of paint, yeah, pretty much any airbrush will do. A nicer airbrush is kinda like a nicer car. It’s a hell of a lot more pleasant to sit in traffic in a Mercedes than an early 90s Kia, but nothing about the drive will really change.
The difference comes with specialty work.
To keep the driving analogy going, let’s pretend that broad work – laying down primers and clear coats for example – is the equivalent of hauling a trailer. And fine, detailed work is like carving corners on a winding country road.
An early 90s Kia is going to suck ass at either of those specialized tasks. For towing, you’d want a truck with the power and gearing to haul the appropriate load. For cornering, you’d want something small and nimble with a finely tuned suspension and excellent steering feel.
If you’re learning or seeking out something of a more general purpose airbrush, a knockoff will probably work just fine. But as you start to push against its performance limitations, that’s when you want to consider investing in something higher end.
C – Type of Airbrushes
If you’re new to airbrushing, sorting out all the terminology of airbrushes can be kinda confusing. What’s the difference between single and double action, internal and external mix, blah blah?
Internal vs. External Mix – Refers to where the air and paint mix. Internal mix airbrushes combine the two inside the body, forcing air to flow past the nozzle and pulling paint with it because physics. External mix brings the two together outside of the body. Externals are generally clunkier, but can still be good for broad work. The most common example is the Paasche H.
Single vs. Double Action – Refers to what happens when you use the airbrush’s trigger. With a single action, the trigger unleashes airflow, and that’s it. You have to use a separate control to regulate the paint flow. With a double action, pushing down on the trigger opens up the airflow, and pulling back on it pulls the needle back to allow more paint to flow through the nozzle. It sounds complicated, but it’s second nature once you get the hang of it.
Gravity vs. Side vs. Siphon Feed – Refers to where the paint comes from. Gravity feed airbrushes have a cup that sits on top of the body. Paint enters the needle channel thanks to gravity. Side and siphon-feeds plug in from the side (dur) or the bottom and paint is sucked into the needle channel because physics.
What do I prefer? Internal mix, double action, gravity feed.
D – My Airbrush Lineup
I’ll be the first to admit that I’m a total airbrush whore. I’ve got several. And I’ve sold several more. Unlike cars, it’s nearly impossible to “test drive” an airbrush. Ones I don’t like I’ll turn around and sell as used – lose a bit of money in the process, but not as much as you’d think.
Anyway, here’s my current preferred roster. Note though – I very much prefer painting small, even on larger kits, so what I consider a workhorse, others may consider a detail brush.
Broad (for clear coats, primer, etc):
Iwata Revolution CR-M2 – A nice, compact single action airbrush that can spray pretty fine, but opens up for a nice, broad pattern.
Grex Genesis XGI – This airbrush is basically Grex’s Tritium airbrush, but instead of the Tritium’s pistol grip, it uses the traditional “stick” layout. It can swap in multiple needle/nozzle sizes, can be equipped with a fan tip, has swappable paint cups of different sizes, and sprays very nicely. Though I find it sprays broader than my Iwatas (the 0.3mm needle puts out a pattern broadly similar to my HP-CS with a 0.5mm needle).
Iwata HP-C Plus – This airbrush is great at the middle range – from pretty fine detail to more than broad enough for my purposes of applying paint. I’ve swapped in the 0.2mm needle/nozzle combo from other airbrushes in the High Performance Plus line.
Olympos HP-62B – Olympos’ airbrushes are the direct ancestors of many of Iwata’s higher end airbrushes. This one is broadly identical to the Iwata HP-B+, save only for the fancier preset handle on the B+. It has a smaller paint cup than the C+, but otherwise behaves about the same. Again, good for that midrange.
Iwata Custom Micron CM-B – I managed to score this one used off eBay, and probably count it as the single best modeling purchase I have ever made. Before you try one, you think “how good can these things really be”. And then you try one. This is my go-to for a lot of my painting, and I wouldn’t have it any other way.
E – What else do you need?
An airbrush is the obvious step one in getting an airbrush, but what else do you need to make it work?
- Air source – Most people go with a compressor, but if you have convenient access to a welding or gas supply store, you might also consider getting a CO2 tank. Just don’t go for those compressed air cans – they’re expensive as shit and have incosistent airflow.
- Regulator – A regulator controls the air pressure coming from your air source into your airbrush. Get one that has a lot of precision from the 0-40 psi range.
- Moisture Trap – Duh. Moisture and airbrushing is a bad combo.
- Braided Hose – Just get one. They’re tough and they don’t get tangled up.
- Quick Connect – If you run more than one airbrush, you want to invest in these. They make swapping brushes a 5 second task.
- Ventilation – Don’t airbrush in a closet. Even with acrylics. Breathing in atomized paint is bad. I spray in my garage. Others have cool spray booths with exhaust fans.
- Respirator – Again, breathing in atomized paint is bad. Get a respirator. I’ll admit I don’t use mine all the time – when I’m spraying small I’m throwing so little paint around that I’m sure plenty of other things will kill me first. But for primers and clears and metalizers and other things that call for more paint flow, definitely a good idea to have one around.
Part II – On Selecting Primer
A – Why Prime?
I highly recommend priming for several reasons. First, to give yourself a uniform canvas from which to build your paint scheme – no junk like different colored putty and so on peeking through. Second, a good primer will etch into the plastic, giving paint much better adhesion than going over bare plastic. Third, in reverse, a good primer will protect the plastic from hotter paints than can craze and otherwise deteriorate polystyrene.
There are plenty of people who don’t prime and they’re pretty set in their ways. But I would highly recommend it.
B – Good Primers
There are some primers that have proven unreliable enough that I would never go near them – Vallejo’s primers, Alclad’s gloss black base, Model Master Acryl primer all come to mind. And in general, acrylic primers are going to be somewhat hobbled because they don’t etch into the plastic the way a good enamel or lacquer primer will.
So what do I consider good primers?
Model Master Gray Primer – The old classic, and if enamels are still your thing, you can’t go wrong here. Darker gray than most other gray primers, it dries to a nice, clean semi-matte finish.
Tamiya Fine Surface Primer (rattlecan) – Okay, I hate Tamiya’s weird ass paint strategy of releasing so many things as rattlecan only . That includes their primer. But decanted, this stuff is rather nice and has the benefit of being widely available.
Badger Stynylrez – Stupid, stupid name, but probably the only acrylic primer that I’ve ever used that I would use again on purpose. It sprays like absolute shit, and looks like absolute shit as it hits the surface, but over about ten minutes, something amazing happens. It levels out to a perfectly smooth finish. It’s important to give it at least 24 hours to really set, but after that, it’s more or less as impervious to paint as lacquer primers. Note though – it has a weird tendency to attract dust (I think it might be a static charge thing), and it’s susceptible to scratches. Also available in Europe as UMP Ultimate Primer.
Tamiya AS-12 Bare Metal Silver – A primer in all but name, this metallic doesn’t really look like bare metal silver. It’s closer to aluminum lacquer paint and therefore great for Mustang wings, postwar RAF aircraft and so on. But it also goes on wonderfully and is tough as nails. It’s especially useful as a primer on something that will be getting heavily chipped.
Gunze Mr. Surfacer 1200 – See above comments about Tamiya Fine Surface Primer. This stuff is similar, but you can also get it in a pot and mix yourself. While it goes down nicely for the most part, it can be prone to dusting – which is when some particles of paint dry before they hit the surface and don’t level in. No biggie, though, just come back with a fine grit sandpaper or some fine steel wool (or sometimes even an old t-shirt) and a few swipes will result in a scarily smooth finish.
Gunze Mr. Surfacer 1500 – 1500 doesn’t have as much “body” as 1200, and that’s great for priming a well-prepped surface. It also comes in black, which is even better. Available by the pot or in rattlecan form if you’re a goddamn barbarian.
Of these, I use Mr. Surfacer 1500 Black about 85% of the time. Stynylrez and Tamiya AS-12 make up the balance.
C – When acrylic primers make sense
Ha! Not really. As much as I love my Mr. Surfacer, there are times where it makes a ton more sense to use an acrylic primer, and by acrylic primer I mean Stynylrez.
Case 1 – Hard to reach areas prone to dusting. Think about, say, the gear bays of an aircraft, or the intricately detailed wheels of a car kit. If your lacquer primer dusts on you in there – which it could, since airflow gets wonky in confined spaces – good luck getting sanding materials in there effectively. In cases like this, Stynylrez is a great alternative.
Case 2 – Kits that use non-styrene parts. Probably the best case here is Meng and their workable tracks. If the tracks are made of styrene, it’s a softer variety, and there are real-world examples of harsher paints like lacquers and enamels degrading them. Again, a good case for using an acrylic primer on these.
Part III – Paints
LOL – paints are such a minefield, especially with the shoddy and confusing labeling so many of them use. Generally, I would consider it a wise choice to not go all in on just one brand of paint – personally I usually bounce between three. Options are good! So is knowing their limitations and what it takes to get them to perform at their best.
A – Types of Paints
Very generally speaking, there are three types of paints – acrylics, enamels, and lacquers. Now, the reality is more complicated. For example, Tamiya’s paints are alcohol-based acrylics, but they thin and spray wonderfully with lacquer thinner.
I don’t think there’s any one perfect paint – each one includes some kind of compromise.
Enamels – Growing up, Model Master enamels were the shit. I didn’t know of any other paints. Nowadays, I feel like I see enamels referenced less and less, though, and probably because they have some drawbacks other types of paints don’t.
Enamels can be both airbrushed and brush painted, so the flexibility is nice. They’re also pretty slow-drying, so useful for drybrushing and various weathering applications.
Unlike water-based acrylics, enamels are toxic and make poor drink mixers. And unlike acrylics and lacquers, enamels can take a long time to fully cure. Even for patient builders, waiting a week for your paint to outgas its happy ass is aggravating.
I’ve also noticed that enamels can’t be thinned down to the extremes that lacquers and alcohol-based acrylics can. At a certain point, paint separation becomes a real issue. Adding some lacquer thinner into the mix can help – it’s extra heat keeps things in check a bit – but still it feels like a band-aid.
Water-Based Acrylics – These are increasingly found in those dropper bottles favored by Vallejo, Ammo, Hataka, AK Interactive and so on. Often they come pre-thinned for airbrushing. A few brands – Lifecolor comes to mind – still use more regular paint pots.
Water-based acrylics generally thin best with their own thinners (though I’ve heard UMP thinner is great, I have yet to try it). Water can work, but if you’ve ever sprayed water through an airbrush, it has a tendency to spider and suffer from the ravages of surface tension.
Water-based acrylics, like enamels, generally have a limit to how far they can be thinned. This also impact their ability to truly spray small.
These paints also have to be built up in layers. Lifecolor I think is the most notorious for this, but far from alone. Lifecolor only likes to go down over other Lifecolor, so your first layer has to be built up gradually, each layer getting more “bite” over the previous. The same holds true for Ammo.
Water-based acrylics don’t bite into preceding layers very well, so they can also be far more prone to tape lift. Not a big deal if you’re doing armor, but an aircraft that requires lots of masking may be asking for trouble.
And of course, water-based acrylics have to contend with the dread “tip dry”. Tip dry occurs when the paint literally dries on the needle or in the nozzle as air passes over it. This leads to lots of frustration and expletives, especially because it tends to kick in worst when you are trying to paint small (not enough paint flow to keep things moving). The common solution is to wet the tip with water or thinner on a q-tip or paintbrush, but a more elegant solution is to add some retarder to the paint. It won’t magically fix everything, but it’ll cut down on tip dry to a large extent.
Water-based acrylics are also generally excellent for brushpainting. I keep a stock of Vallejo Model Color around expressly for detail work.
Lacquers and Alcohol-Based Acrylics – I’m lumping these two together as both thin down with lacquer thinner and both have very similar performance characteristics. But I’ll note that you can thin alcohol-based acrylics like Tamiya with water, with UMP thinner, and even with isopropyl alcohol. Just don’t expect it to have the same spray characteristics it does with lacquer thinner.
Okay, let’s get the bad out of the way. Lacquers ain’t great for brushwork. They’re also toxic and generally a bad thing to come into contact with. All the best modeling materials are.
The good? Lacquers spray beautifully. Just beautifully. If all you’re used to is shoving Vallejo (or god forbid some kind of trashy craft paint) out of an airbrush, the first time you try a quality lacquer, you will shit your pants and start crying it’ll be so beautiful. And because lacquer thinner cooks off so quickly, they aren’t as prone to run, and they dry basically as fast as acrylics.
Lacquers can also be thinned to within an inch of their lives. My favorite paint – Mr Paint – already comes thin and ready for the airbrush, but for fine work I’ll bump it a bit more. For Tamiya and Gunze paints, my starting ratio is 2:1 thinner-to-paint, but I’ve pushed it to 80, 90% thinner before and still had things hold together.
This ability to thin so far means that lacquers can be applied in translucent layers, super effective for building up a nice, varied paint finish.
Due to their hotness, lacquers are also good at grabbing surfaces, so tape lift isn’t a huge issue unless there’s some kind of contamination or weakness under them.
I thin my lacquers and alcoholic acrylics with Gunze Mr. Leveling Thinner. It’s got some kind of retarding agent in it that helps prevent dusting but I haven’t found that it does anything to prolong drying times.
B – Choosing Your Paints
What paint works best for your needs depends on several factors. Selection, availability, and the conditions in which you paint all matter. What you will be doing with the project matters. The type of subject matters.
Personally, my three main go-tos are Mr. Paint, Gunze Mr. Color, and Tamiya. As mentioned above, I love the way all three of these spray and perform, and I feel like I have a level of control with them that isn’t present with other paints.
That said, I will be using AMMO acrylics on an upcoming armor build, because it will be a single color scheme and their chippability plus the assortment of various shades around the color I need will enable lots of interesting subtleties.
IV – Thinner and Air Pressure
Okay, so we’ve covered off on airbrushes and paint. Now it’s time to bring them together. But first, we have to get things ready.
A – Thin your fucking paint
Some paint brands come pre-thinned for airbrush use. But what constitutes “thinned” is pretty relative based on what you want to do with the paint. Sometimes – gasp – you may have to thin them further.
Paints like Tamiya, Gunze, Lifecolor and Model Master that come in regular pots will all need to be thinned before spraying.
Thinning makes paint flow better through your airbrush, less likely to clog your airbrush, and eases cleaning at the end of the session. It also lets you reduce the coverage – or opacity – of the paint, so you can build up in layers and be more controlled in how you’re applying shit to your model.
How to thin?
First, get a container. DO NOT THIN OR MIX PAINTS IN YOUR AIRBRUSH. This is lazy and a wrong move can jack shit up. Nothing like having incompatible paint and thinner turning to sludge in your nice airbrush, right? Take the extra thirty seconds and mix in a separate container.
My favorite mixing containers are tattoo ink cups (15mm size). You can find them on eBay for ridiculously cheap, and they’re nice and small so you’re not wasting paint and thinner you’ll never get to use.
Next, get a way to transfer paint to said container. Those silly acrylic dropper bottles have that built in. For other paints, again, to eBay! Buy a fuckton of disposable pipettes and go to town. You can kinda sorta re-use them, but when you can buy them by the thousand…
Okay, so next, you use the pipette to grab a bit of paint. Drop a small amount into one of those ink cups. If we’re talking Tamiya or Gunze I’ll only fill about the bottom third or so. THEN, get some thinner with another pipette, and fill the rest of the way.
Once you’ve added paint and thinner, stir to mix. I’ve got a Tamiya mixing stick that I love, and it’s big flat face helps me gauge when I’ve mixed enough. You kinda have to learn what a well-thinned paint looks like, but if you stir and come away with solid, uniform color coverage on the mixing stick, you need more thinner.
There’s that old adage of thinning “to the consistency of milk”. Fuck that. Personally I prefer to mix my paint to the consistency of lacquer thinner with some percentage of paint in it.
Note: Do not ask me for my thinning ratios. I don’t know. It’s like asking a mountain biker what gear they’re in. Uh…the one that feels right for the terrain and fatigue level. Same with paint – I’m familiar enough with the paints I use that I start at 2:1 and add thinner from there as needed, based on what I’m going to be doing with the paint. With things that are pre-thinned, like Mr. Paint, I’ll just add a few drops, mix, and then add a few more drops as needed. It’s not like I mix in precisely 73% thinner or anything.
B – Dial it in
The other key ingredient of airbrushing is air. How much do you need? As with thinning, I have some rough starting points and then dial it in further. Your mileage may vary based on altitude, humidity, temperature, paints etc. But for me:
- Mr. Paint – 5-10 PSI
- Tamiya and Gunze – 8-15 PSI
- Primer – 15-20 PSI
Again – shit varies within and even slightly beyond that range, but it’s a starting point.
It also helps to have a slightly higher pressure running as you load and test-spray paint. Once it’s flowing, THEN dial it in.
V – How to Airbrush
At its most basic, an airbrush is simply spraypaint that you can control. You push down on the trigger to unleash pressurized air, and that air flows past the needle, pulling paint along with it thanks to the venturi effect. Science, bitches.
However, just like driving is more than mashing the accelerator pedal, airbrushing is way more than mashing the trigger and screaming “yeehaw”.
A – A few “settings” that matter
Apart from making sure your paint is properly thinned and your air pressure is dialed in, there are a few what I’ll call “settings” that determine how well or not your airbrush does its job.
Distance – Generally, you don’t want to get to standoff distance with an airbrush. There are times where it’s useful, but this isn’t a rattlecan. If I’m working small, I may be right up against the surface. If I’m doing something broader, I may back off to three, maybe four inches. Very, very rarely more than six.
Movement – As with sharks, with airbrushes. To stop moving is to die. Hold an airbrush in place too long and you’ll get a flood of paint that will run, spider, fisheye, and so on. Keep moving, even if you’re doing tight mottling work.
Paint Flow – Just as air pressure and airflow matter, so does paint flow. If you crank back on the trigger on a double-action airbrush, you’re going to drastically increase the flow of paint, and this often ends poorly, with a big nasty sploosh on the project you’ve been slaving over.
B – Think in terms of opacity
I think airbrushing is really a lot easier to get a handle on if you know Photoshop. In Photoshop, you can dial the opacity – how transparent or not something is – for just about any element.
If you set the airbrush tool to 15% opacity, every time you go back over it will add another 15% opacity, until it gets to 100%. It’s the exact same with a real airbrush. Opacity builds up over time.
IF you try to get to 100% opacity in one go, you’re going to have a bad time. Plan to put down a layer, then move on, then come back.
C – Learn Spray Discipline
In many ways, operating a double-action airbrush is similar to driving a stick shift. Both require a certain feel, both take a bit of time to get the hang of, and once you do, both seem like second nature, like an extension of yourself.
There are two things that I have found to be really useful in developing good spray discipline and not shooting paint all over the damn place.
First, work to develop a sense for your airbrush’s engagement point. That is, the point when you can get beyond air, to where paint starts flowing. That point differs from airbrush to airbrush and paint to paint, but as with thinning ratios and PSI above, it’s one of those things that’s generally in a certain range, and once you find it, you can go back to it again and again.
Second, get comfortable playing in only the first third to half of a trigger’s range. There are times where you will find it appropriate to pull all the way back and let shit fly, but in my experience, those times are rare, even when applying primers and clear coats. Instead, you want to be metering exactly how much paint is flying at your model. To return to driving analogies again, you could drop the clutch and slam on the gas and go, but it is a poor and inelegant way to go about it.
Some airbrushes have presets build into the handle that are essentially little more than needle stops. These keep you from moving the trigger back past a certain point. Personally, I can’t stand them. To me they’re like training wheels, and frustrating when you need to take the airbrush away from your model to blow it out at full blast (even really nice lacquers can start to build on the tip if you’re spraying small).
Once you’ve got paint flowing in a nice, controlled fashion, keep the above settings in mind – so keep the airbrush moving, stay as close to the surface as your spraying dictates, and don’t try to get it all in one pass. Come back, build your paint lovingly, in layers.
And unless you’re dealing with something that needs a broad, uniform finish, like paint on a car model, or a clear gloss, don’t spray any wider or harder than you need to. Every so often I’ll see models that are hilariously masked from head to toe just to contain overspray from a band on the fuselage.
This is crazy. If you’re getting overspray more than six inches from where you’re spraying, you’re doing something wrong.
D – On Spraying and Masks
Often on a kit, it’ll be necessary to mask something – a canopy, camoflage, some area where you don’t want your paint to go, and the like.
And frequently online, you’ll run into people having problems with paint bleeding under their mask.
This shouldn’t happen, and it’s fairly easy to avoid.
We’ve already discussed going light, and building paint in layers. This is doubly true for when spraying around masks. If you don’t flood paint at the area, there’s not enough paint hitting the surface to run under anything.
To further lessen the chance, and to prevent paint “ridges” where the masks are placed, imagine a 180 degree arc over the surface. At 0 degrees, you would be spraying along the surface directly at the edge of the mask. At 180 degrees, you’d be spraying along the top of the mask out toward the surface.
Generally, you want to keep your spray angle greater than 100 degrees. This will ensure that 1) there is no air flowing at the mask edge. No airflow in that direction, no paint flow in that direction. And 2) paint won’t “ridge” up against the mask edge.
Now, there are times where this isn’t entirely possible. Consider canopy masks. If you’re trying to paint a canopy frame that’s 1mm wide, and you have masks on either side, if you go too oblique on one, you’ll be spraying air straight into another. In these cases, the key is to BACK OFF. Back off the pressure. Back off the paint flow. Build the paint up lightly and gradually.
Soft Edge Masking
Hard edge masks, such as you’d use for canopies or anti-glare panels or hard-edged camoflage, are fairly straightforward. Use tape, burnish it down.
But what about soft-edged camoflage?
Personally, unless it’s a very, very tight soft edge like seen on many tropical schemed Spitfires, I prefer to freehand. But…I have that Custom Micron and paints that support that kind of work. If you’re just starting out, or using paints that don’t really do so well at spraying small and tight, you can still use masks.
One popular method is to roll out sausages of poster putty (also called white tack). This stuff will stick just enough to your model to let you do the work. To get a soft edge, spray out over the sausages, again at that 100-plus degrees angle. The more that you spray straight down onto the masks, the harder the edge will be. One issue with this method though, is that you need to keep that angle pretty consistent, or else you’ll end up with some parts of the camo demarkations softer than others.
Another method I prefer is to trace out the camo pattern on paper – tracing paper is pretty good for this, and then cut it to shape. Once you have your pieces, trim the inside so that you effectively have a 1/4″ ribbon, and tape the inside portion down. When you spray, the untaped edge will flap slightly under the airflow, naturally creating that slightly soft edge.
Again, though, once you can, freehand is generally the cleanest and least burdensome way of tackling softer-edged camoflage.
All for Now
So…closing in on 5000 words…think it’s time to wrap it up for now. If this finds enough traction and interest, I’ll follow up with some more advanced techniques – stippling, mottling, tackling exhausts and that kind of thing.