An airbrush needs a supply of pressurized air. The easiest way to get this is from a compressor, and that’s what this page is about. That’s not the only source though, and I’ll touch on some of the others.
I’ll get this one out of the way straight off: many beginners’ brushes are sold with adapters to let them operate off cans of compressed air. This is called, unsurprisingly, “canned air”. This is about the worst possible air source (blowing into the end of the hose might be worse, but note that I say “might”).
The chief problem with canned air is that like any pressurized spray-can, when you use it, it gets cold, to the point where ice will form on the outside. As it gets cold, the pressure it produces will drop from a reasonable level (perhaps even too high) to too low to atomize the paint, at which point you’ll get spatters on whatever you’re painting, ruining the finish. And then you’ll run out of air until the can defrosts. You can avoid this to some extent by putting the can in a large basin of warm (not hot!) water, but it only helps a little.
And the cans don’t hold much air, and aren’t cheap. You’ll spend money that could have bought a compressor fairly quickly.
Whoever thought that selling these to beginners was a good idea was an idiot, or perhaps a sadist.
Compressed Air Tanks
You can get large compressed air tanks, equip them with appropriate fittings (and a regulator) and take them to some place that will provide pressurized air or a “safe” gas, either for free or at a relatively low cost. This is fairly inexpensive, and a big tank (tens of gallons) will run an airbrush for hours. The downside is that you’ll run out eventually, likely at the worst possible time, and you’ll have to cart the tank back for a refill. That said, lots of people swear by this approach. And if you’re enough of a handyman to deal with getting the fittings correct, it can be an economical solution.
If you use something other than air, like nitrogen or carbon dioxide, keep in mind that these displace normal air. If you spend a whole evening airbrushing in an unventilated basement, you could manage to kill yourself by suffocation. Of course, airbrushing in an unventilated basement is bad for many other reasons. Using a tank of one of these gasses in a properly ventilated room is quite safe. Just be careful: “death by airbrush” isn’t an epitaph anyone wants.
And don’t, I hope it’s obvious, use a flammable gas like propane for a grill. The only thing worse than asphyxiating yourself is blowing up your house.
One benefit of the large compressed air tank approach is silence. Since there’s no compressor, there’s no noise beyond the hiss of air from the airbrush. Very useful if you want to paint after the kids are asleep.
No, not the belly you get from sitting at a bench every night working on models, a real spare tire. It may seem silly, but a tire holds 30 - 40 psi (more if it’s a truck tire). And unlike canned air, it doesn’t chill down significantly when used. Fill one up at the gas station for free (if you can find a gas station that still has free air; all my local ones charge for it now) and, with the right fittings, you can run an airbrush for a fair amount of time at no cost. This is really just an inexpensive variation on the compressed air tank. But apparently it works well enough that a number of people use it, and you can get adapters to connect an airbrush to a tire. Badger makes one (part 50-029, US$6) that works with its canned air (“propel”) regulator and a tire inflated to 40psi. I can’t say I think this is a great solution, but it could be a way to get started cheap until you can afford a compressor.
Note: Badger’s Propel “regulator” (just a valve, really) is rated to 50psi (that’s also the rating of their simple vinyl hose), don’t use a tire with more pressure than that.
Now for the real stuff. There are basically three kinds of compressors you can use, in order of increasing cost:
1. Compressors made for pneumatic tools like nail-guns.
2. Typical “Airbrush” compressors.
3. Really expensive “Airbrush” compressors.
You might think #1 wasn’t a good choice, but if you can live with the problems, these can be a very economical solution.
One important maintenance tip: with any compressor, water will condense inside the tank as soon as you pressurize it. At the end of an airbrushing session, let all the air out and open the tank’s drain, to prevent any internal rust from forming. If you value your tools, make that as routine as cleaning your airbrush at the end of a painting session.
A compressor made for use with air-powered tools will typically have a tank of several gallons capacity, pressurized to 125 psi (8.6 bar) or more. This is enough to run an airbrush for some time. The downside is that when the compressor kicks on to refill the tank, it’s going to be fairly loud (as in “not for apartment use” loud). There may be exceptions to this; I’ve read claims from some people who use them that some models are reasonable. On the other hand, I’ve seen some rated for 98 dB, which is loud enough to cause hearing loss with repeated exposure. This is about as loud as a lawn mower up close. Unless you can try on in the store, which isn’t likely, there no real way to know just how loud one will be, as noise specifications for these aren’t common.
One way to use these if the tank is large enough is to fill them when noise won’t be a problem (mid-day, out in the driveway, for example) and then unplug them and use the tank for a painting session where you want to be very quiet (in the evening, say). With a big tank, one will run an airbrush for some time (I don’t have exact info, unfortunately). And with just a tank, it’s very quiet.
Tool compressors usually come with fittings that aren’t compatible with an airbrush, so you’ll need to adapt. In the U.S., the standard fitting is called an “NPT” (National Pipe Thread) fitting. These come in a variety of sizes, but even in 1/4” size, they likely aren’t compatible with airbrush hose fittings. I cover that more on the Airbrush Hoses and Standards pages. But you’ll need an adapter to connect an airbrush hose, and perhaps multiple (one to convert from 1/2” or whatever down to 1/4”, and one to convert from 1/4” NPT to whatever your hose uses).
Note: many airbrush hoses use 1/4” BSP fittings at the compressor end, but this varies a lot, you’ll need to identify your brand of hose, and get the right adapter.
Outside of the U.S., the compressor may use BSP (British Standard Pipe) fittings, but you could still find yourself needing to convert sizes. In Europe, connections will likely be metric (e.g., “DN 12” is a large metric fitting I’ve seen on some compressor specifications). Even when things are the same size, the threads are usually different: you can’t connect a 1/4” BSP to a 1/4” NPT fitting; either it won’t go on at all, or you’ll strip the threads, or you’ll get it partially connected and it will leak like a sieve. Sometimes you can deal with that using thread-seal tape. But there are adapters and they’re fairly cheap; buy the right kind for what you need.
A tool compressor will normally have a regulator, but it won’t necessarily be good for fine control. It will likely also lack a moisture trap. You may want to use its regulator to step pressure down to a level that’s safe for your hose (like 50 psi or less for the smooth hoses) and then connect an airbrush regulator with moisture trap to step that down to the pressure you want to use at the brush.
Tool compressors are typically piston-type compressors, which need their oil changed periodically. You also need a filter to catch any oil in the air (the moisture trap should do this).
The upside is that even after adding a regulator and moisture trap, and various adapters, the cost is still going to be well under US$200, possibly under US$100.
Compressors sold for hobbyist airbrush use can range from very small and relatively inexpensive, to ones costing several hundred dollars, but expect to spend close to US$200 at a minimum before you’re done. The smallest ones are probably too small for hobby use (they’re designed for artists working with ink, or makeup application (yes, people use airbrushes for that).
Inexpensive ones typically lack a tank, and while you don’t need a tank, it’s a good idea to have one. Without a tank, the compressor runs continuously while you’re airbrushing, and this will cause it to heat up, and shorten its life. Paying a bit more for a compressor with a tank will likely extend the life of the compressor. A small tank will add between US$50 and US$75 to the cost.
And if you’re going to spend the money on a compressor, get one with a regulator, pressure gauge, and moisture trap. This may add as little as US$20 to the cost (some cost more), and the added convenience is well worth it. You need the regulator to adjust your airbrush pressure to the paint you are using, and the moisture trap to keep condensation out of the paint you’re spraying (one drop of water can ruin the whole finish on that model you just spent hours on). In really humid climes, you may want a second moisture trap at or near the airbrush to catch any condensation that formed in the hose.
Typical hobbyist compressors are oil-free diaphragm type compressors. These are simple and essentially maintenance free, but won’t last as long as a compressor that uses oil to seal a piston.
A good airbrush compressor will have an air filter on its inlet, which will need to be replaced when it gets dirty. A cheaper one won’t have a filter, which means the dirt ends up in your air. Most moisture traps include a filter element to catch larger dirt particles, but it’s still better to have an inlet filter.
Most hobbyist compressors are relatively quiet, varying between about 45dB (just enough to wake someone sleeping) and 65dB (equivalent to loud conversation).
Expensive Airbrush Compressors
The last category is the really high-end model, designed for professional use. These are typically oiled piston-type compressors, which can survive being used all day, day after day. They’re also quite often the quietest type, sometimes as low as 40 dB (the noise made by a typical refrigerator). These will cost US$500 or more (to above US$1000). These may still be tankless, and some are low-pressure units for specialty use that aren’t suited to hobbyist airbrushing.
Actually, there’s a fourth category. Take the Compressed Air Tank mentioned earlier, hook it up to a refrigerator compressor (with appropriate fittings) and you’ll have a very quiet, very reliable, and relatively inexpensive airbrush compressor. It’s definitely a job for the seriously mechanically-inclined. But if you Google about, you’ll likely find descriptions of how to do it by people who have made them.
How Much Air
One of the fundamental questions people ask about airbrushing is “how much air do I need?”. Unfortunately, there’s no single answer. I’m going to ignore non-hobbyist applications, since people painting clothing or metal have wholly different requirements from people painting plastic and resin kits. But that still leaves lots of room for variation.
Painting with really heavy paint (like acrylics) needs more air than painting with really fine paint (like lacquers). Painting with a bottom-feed airbrush (often used for primer coats) needs much more air than a gravity fed airbrush. The “conventional wisdom” is that you probably need about 30 psi (2.1 bar) at the airbrush (so a bit more than that at the compressor). But I’ve read of plenty of people who paint at 15 psi (~1 bar), and others who use 40 psi or more. You’re probably okay with a compressor rated for 30 psi, but a bit more won’t hurt since you can regulate it down to whatever you need, but you can’t regulate a weak compressor up.
The other measure of air use is typically given in either cubic feet per minute (cfm) or liters per minute (l/min). At the low end of the scale are compressors rated at 0.81 cfm (23 l/min). There are ones rated lower, but you’ll probably be disappointed with one of those. At the high end are compressors rated for 1.2 cfm (34 l/min). These will be able to handle more challenging jobs, but are probably overkill for most hobbyist painters. Of course tool compressors are typically rated much higher.
If you have a tank, cfm only matters for refilling the tank, since you’re likely to pause often enough for even a low-cfm compressor to refill the tank. Still, higher cfm means the compressor runs less, reducing wear and tear on both it and your ears. If you have a tankless compressor, then cfm matters more, but probably even the smaller compressors will work. I don’t have good info on this, but I’d avoid anything less than 0.8 cfm. I’ve heard 0.5 cfm is fine, but I have a 0.4 cfm compressor and it had problems when I tried to switch to heavier paint (the problems may have been my lack of knowledge, however).
When the airbrush isn’t using air, the airbrush can turn itself off if equipped with an automatic shutoff. This helps prolong its life. You can do without this (some manufacturers provide convenient foot switches so you can turn the compressor on and off yourself). But it’s a really nice feature to have.
On a compressor with a tank, there will usually be an automatic shutoff that turns the compressor off when the tank is full, and on at some reasonably low pressure that’s above what you’d set the regulator to. With this, the tank will always have more air than you need, and the compressor will only run when needed. If you get a tank compressor, make sure it has an automatic control (there are a few without one, and I have no idea why).
So you bought a compressor, are you done? No, of course not, nothing’s ever that easy.
Regulators and Moisture Traps
I’ve mentioned these before. Some compressors come with these, others do not. But you really, really, want them.
A regulator takes the pressure from the compressor and reduces it to a useful level. Depending on what you paint with, useful can be anywhere from around 10 psi (0.7 bar) to 40 psi (2.8 bar), but it’s probably around 20 - 30 psi (1.4 - 2.1 bar). Note that a compressor will only reduce pressure, so you’ll need a compressor that puts out a higher pressure (as noted above). A good regulator will have a pressure dial, and a knob (typically pull out the knob and turn it to change the setting). To set an accurate pressure, push the trigger on your airbrush to run air through it while setting the pressure. This works best if you don’t have paint loaded, or have a double-action brush that lets you turn on air without paint.
The moisture trap is usually attached to the regulator, and takes the form of a glass or plastic bottle with a drain at the bottom. When you see a visible amount of water build up, open the drain to let it out, but close it securely to keep the air in while painting. You can also get small moisture traps that attach to an airbrush like a handle, or inline traps that go between two lengths of hose. These two kinds are usually used as second moisture traps in addition to the one at the regulator.
Note: a moisture trap only catches water that made it into the hose. If you have a tank, you still need to drain it at the end of your session to let out any water that built up inside.
Moisture traps work best when the air has a chance to cool, so some manufacturers put a short length of coiled hose between the compressor and the trap. This also helps to smooth out “pulsation” in the air caused by the diaphragm or piston in the compressor moving back and forth. If your compressor doesn’t have this, you can always add it, just buy a hose with the right fittings, or adapters.
Hoses and Related Fittings
Your airbrush probably came with a hose. If the compressor is from the same company it should work (some companies provide more than one kind of hose, Badger among them). Otherwise, you’ll need to buy an adapter to make the hose fit the compressor. Alternatively you can use a compressor-compatible hose and put a quick-release fitting on the airbrush end, as there is a fairly standard method for this, and adapters for just about every kind of airbrush.
The material on this topic has been placed on a separate Airbrush Hoses page, as it turns out to be more than a little complex.